I am in the process of installing a subpanel to consolidate the wiring in my
workshop. The panel is rated for 150amps, but I purchased a 125 amp to
install in the main panel. I additionally have a 100amp breaker as well.
The largest bound copper cable I can get without a special order from the
local electrical supply house is 2/3 which will handle up to 95amps. I
would prefer not to wait for the special order if I don't have to. 50amps
is the next size down at the local Home Depot, ( I need to see what the
electric supply house has, I assume I can get a 70, 80, or 90)
My questions are:
1. I am thinking that I really don't need 100amps, so I wanted to query
others to see what they have installed. (I am in the process of totally up
the equipment and amps that I would expect would be needed at a given time
to make sure I have all that I need, but that is not complete) I do have a
fair amount of machinery and can see 2 - 3 users larger pieces of equipment
plus auxillary air compressor, dust collection, air filtration, general
power consumption that will add up. In my mind, it's not that much more
expensive to add the extra amps at this point and would rather overplan than
be under powered at a later date which would be much more expensive to
upgade, if I needed it.
2. I can purchase Aluminum to handle the 125amp's but I have heard bad
things about the aluminum connection corrosion. I know I can put the
special grease on the connections to prevent the corrosion. Any thoughts or
comments?
David
In article <2SF7e.1714$H53.1103@lakeread05>, "DL" <[email protected]> wrote:
>Given that I have already have the 100 and 125amp breakers for the main
>panel which I would prefer to use, the cost difference in the wire is
>minimal given that we are talking < 50' distance.
Well, it's not just the cost. Heavy cables are a PITA to work with. They don't
bend easily.
One thing I meant to mention in my first response to you, that I think I
omitted: make sure that the cable you use to feed the subpanel has a grounding
conductor. You need 2/3 WG (With Ground), not just 2/3. In the subpanel, the
equipment grounding bus bar and the neutral bus bar must *not* be connected.
> If I am correct, just
>like the main panel at 200amps, if you only put one 20amp breaker in, there
>won't be a problem having too many amps being fed into the subpanel, the
>equipment will draw the necessary power it needs from the individual
>breakers in the subpanel.
Yes, that's correct.
>This does go to the point of equipment overload. If I have a piece of
>equipment that draws 25amps and have a circuit consisting of a 50amp circuit
>breaker, 6/3 wire from the breaker to the outlet, and a 50 amp outlet, I
>should still be fine, isn't the logic the same? or do I need to worry about
>overloading the equipment. It has always been my understanding that
>equipment / motors draw the power they need from a circuit. The breaker is
>designed to kick off when too much current is required thus causing a
>situation where the wire would heat up and become unsafe. (goes to your
>temp rating statement above)
Your understanding is correct: the equipment draws the power it needs. The
purpose of the circuit breaker is to protect the wiring and the receptacle,
*not* what's plugged into the receptacle.
>Also, the rotary phase converter I have requires 70-80amp breaker IIRC (I
>have to get with the manufacturer to confirm), though I am not exactly sure
>why a 7.5hp 3 phase motor requires that much. I would figure that while it
>doesn't draw those amps all the time, it is needed at some point, possibly
>startup.
I think you have that right, too.
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
DL wrote:
> I am in the process of installing a subpanel to consolidate the
wiring in my
> workshop. The panel is rated for 150amps, but I purchased a 125 amp
to
> install in the main panel. I additionally have a 100amp breaker as
well.
> The largest bound copper cable I can get without a special order from
the
> local electrical supply house is 2/3 which will handle up to 95amps.
I
> would prefer not to wait for the special order if I don't have to.
50amps
> is the next size down at the local Home Depot, ( I need to see what
the
> electric supply house has, I assume I can get a 70, 80, or 90)
>
> My questions are:
>
> 1. I am thinking that I really don't need 100amps, so I wanted to
query
> others to see what they have installed. (I am in the process of
totally up
> the equipment and amps that I would expect would be needed at a given
time
> to make sure I have all that I need, but that is not complete) I do
have a
> fair amount of machinery and can see 2 - 3 users larger pieces of
equipment
> plus auxillary air compressor, dust collection, air filtration,
general
> power consumption that will add up. In my mind, it's not that much
more
> expensive to add the extra amps at this point and would rather
overplan than
> be under powered at a later date which would be much more expensive
to
> upgade, if I needed it.
>
> 2. I can purchase Aluminum to handle the 125amp's but I have heard
bad
> things about the aluminum connection corrosion. I know I can put the
> special grease on the connections to prevent the corrosion. Any
thoughts or
> comments?
>
> David
"DL" <[email protected]> writes:
>I am in the process of installing a subpanel to consolidate the wiring in my
>workshop. The panel is rated for 150amps, but I purchased a 125 amp to
I installed 100 amps, but I doubt I'll ever need that much. I could
envision the 220V dust collector, 220V Unisaw, and the 220V air compressor
all running at once, but they would take 40 amps or less.
>install in the main panel. I additionally have a 100amp breaker as well.
>The largest bound copper cable I can get without a special order from the
>local electrical supply house is 2/3 which will handle up to 95amps. I
>would prefer not to wait for the special order if I don't have to. 50amps
>is the next size down at the local Home Depot, ( I need to see what the
>electric supply house has, I assume I can get a 70, 80, or 90)
My local Home Depot has wire plenty big enough to handle 100 amps. It is
THHN and has to be run in a conduit. I used three seperate wires to feed
my subpanel.
Brian Elfert
I installed a dedicated subpanel for my shop when I built it a couple
of years ago. I did a fair amount of research in preparation for the
shop wiring and ended up using a 10/20 125amp Siemens panelboard with a
copper bus. I had only a 10 foot run from the main service panel to the
subpanel. The electrical supply store I went to had 25' of already cut
2/3 w/ground copper that someone never picked up, so he gave it to me
for 40 cents/foot and he threw in a 90 amp DP breaker, so that's what I
used (even though the ampacity of the cable conductors is much
greater). I installed ten branch circuits using 12/2 w/ ground NM cable
with 220V and 110V Twist-Loc receptacles (Hubbell - ridiculously cheap
@ $2.50/each by the box on eBay at the time) generously spaced around
the shop for flexibility in tool placement. Next to each Twist-Loc, I
also installed conventional 110V receptacles (industrial grade
Hubbell's, once again dirt cheap on eBay). I installed industrial
fluorescent T8 electronic ballast fixtures as well, divided into two
zones, controlled by 3-way switches at each of two doors. There are
both 4' and 8' dual bulb fixtures with a total of 22 4' bulbs. I made
certain to wire the lighting into the main panel on its own 20A circuit
instead of into the subpanel, so the lights wouldn't go out if the
subpanel breaker tripped (e.g., while I was ripping a narrow piece of
maple). All in all, I used about 600-700' of 12/2 NM for all of the
wiring, but it came out beautiful and works like a charm.
To minimize accidental use of any tools by unauthorized people (i.e.,
kids), I habitually flip off the subpanel breaker in the main service
panel when I'm finished in the shop.
I did make sure that I pulled appropriate permits and had everything
inspected, not because I wasn't confident in my wiring skills, but for
insurance reasons, in the event of an unexpected catastrophe. The
electical inspector turned out to be a woodworker, so for the rough
inspection, he spent more time talking to me about woodworking than
actually inspecting. He said he normally scruntinizes homeowner's
wiring, but said the wiring job was better than most professional jobs
he inspects. We both agreed that this likely relates to the attention
to detail inherent to woodworkers.
Good luck.
Stu
In article <[email protected]>, Duane Bozarth
<[email protected]> wrote:
> DL wrote:
> >
> ...
> > I will have to get the information on the brand (I think S&S) for you as it
> > is stored currently while I am doing the buildout. The unit has a 7.5hp
> > Baldor motor that I purchased based on an original thought that I would
> > purchase older 3-phase equipment and restore it for use in my workshop since
> > I am unable to get 3-phase service. Primary reason for this one was
> > capacity and price. I bought it used in ebay for a good price IMO.
> ...
>
> OK, thanks...it's been a low-level "onna-these-here-days" for some time
> now. I <eventually> want the shop in the barn loft and would like a
> couple larger pieces such as a 4-side moulder and thickness sander that
> could be in the present shop area where the low ceilings aren't such an
> issue...haven't found that bargain as yet (but haven't really searched
> seriously yet, either)...
>
> If one should wander off to SW KS sometime and were in need of a home,
> I'm sure something could be arranged... :)
"Doug Miller" <[email protected]> wrote in message
news:[email protected]...
> In article <iFD7e.1704$H53.1652@lakeread05>, "DL"
> <[email protected]> wrote:
>>I am in the process of installing a subpanel to consolidate the wiring in
>>my
>>workshop. The panel is rated for 150amps, but I purchased a 125 amp to
>>install in the main panel. I additionally have a 100amp breaker as well.
>>The largest bound copper cable I can get without a special order from the
>>local electrical supply house is 2/3 which will handle up to 95amps.
>
> Unless the insulation is rated at only 60 deg C, a 2/3 cable ought to
> handle a
> lot more than 95 amps. Where are you getting that figure from?
The sales rep at the electrical supply stated the 95 and when I did research
on the internet for loads on copper wire, it said the same, even the board
at HD said the same as well. I didn't look in the temperature rating
though. I plan to call the county to see what they will approve. Simplest
would be that the 2/3 would be accepted for the 100amp breaker that I
currently have so I can make the connection and move on with the electrical
work.
>
> You can do 100A in a 4/3 cable if the conductor temperature is rated 85
> deg C
> or higher....
>
I will check with the electrical supply to see what the temp rating is on
the 4/3 and 2/3 they stock.
>>I would prefer not to wait for the special order if I don't have to.
>>50amps
>>is the next size down at the local Home Depot, ( I need to see what the
>>electric supply house has, I assume I can get a 70, 80, or 90)
>
> I would think so. I'm surprised you didn't find a 60 at HD.
I expected to see the 60 and 70 as I have in the past. It could be possible
that they are starting to phase out the GE panels for the CH ones so the
selection of breakers is smaller.
>
>>My questions are:
>>
>>1. I am thinking that I really don't need 100amps, so I wanted to query
>>others to see what they have installed. (I am in the process of totally up
>>the equipment and amps that I would expect would be needed at a given time
>>to make sure I have all that I need, but that is not complete) I do have
>>a
>>fair amount of machinery and can see 2 - 3 users larger pieces of
>>equipment
>>plus auxillary air compressor, dust collection, air filtration, general
>>power consumption that will add up. In my mind, it's not that much more
>>expensive to add the extra amps at this point and would rather overplan
>>than
>>be under powered at a later date which would be much more expensive to
>>upgade, if I needed it.
>
> You certainly have the right idea about the cost of building bigger than
> you
> need vs. the cost of upgrading later. But I think you're going bigger by a
> larger margin than necessary. 60A at 240V will provide more power than
> you're
> likely to need in a home shop.
Given that I have already have the 100 and 125amp breakers for the main
panel which I would prefer to use, the cost difference in the wire is
minimal given that we are talking < 50' distance. If I am correct, just
like the main panel at 200amps, if you only put one 20amp breaker in, there
won't be a problem having too many amps being fed into the subpanel, the
equipment will draw the necessary power it needs from the individual
breakers in the subpanel.
This does go to the point of equipment overload. If I have a piece of
equipment that draws 25amps and have a circuit consisting of a 50amp circuit
breaker, 6/3 wire from the breaker to the outlet, and a 50 amp outlet, I
should still be fine, isn't the logic the same? or do I need to worry about
overloading the equipment. It has always been my understanding that
equipment / motors draw the power they need from a circuit. The breaker is
designed to kick off when too much current is required thus causing a
situation where the wire would heat up and become unsafe. (goes to your
temp rating statement above)
Also, the rotary phase converter I have requires 70-80amp breaker IIRC (I
have to get with the manufacturer to confirm), though I am not exactly sure
why a 7.5hp 3 phase motor requires that much. I would figure that while it
doesn't draw those amps all the time, it is needed at some point, possibly
startup.
>
>>2. I can purchase Aluminum to handle the 125amp's but I have heard bad
>>things about the aluminum connection corrosion. I know I can put the
>>special grease on the connections to prevent the corrosion. Any thoughts
>>or
>>comments?
>
> Under _no_ circumstances would I ever install an aluminum feed to a
> subpanel
> in my home, or advise anyone else to. It's just too risky, and for what
> benefit? Sure, you might save a few bucks, but it's a whole lot less safe
> than
> copper unless it's installed _exactly_ right. Trouble is, it's a whole lot
> more difficult to install correctly than copper is. It's not just a matter
> of
> adding anti-oxidant compound to the connections. Bolt lugs must be
> tightened
> with a torque wrench, both to make sure that they are tight enough, and to
> make sure that they are not _too_ tight, because aluminum will cold-flow
> away
> from an overtorqued connection, loosening it, and causing it to arc. All
> equipment used must be rated for use with aluminum. And so on.
>
> Don't do it. It isn't worth it.
What I expected as a response, just wanted to confirm. The extra money of
the cooper wire is not the issue here. I am trying to get things done and
didn't want to have to wait for a special order if I didn't need to.
Thanks for the advise,
David
>
> --
> Regards,
> Doug Miller (alphageek at milmac dot com)
>
> Nobody ever left footprints in the sands of time by sitting on his butt.
> And who wants to leave buttprints in the sands of time?
DL wrote:
>
...
> I will have to get the information on the brand (I think S&S) for you as it
> is stored currently while I am doing the buildout. The unit has a 7.5hp
> Baldor motor that I purchased based on an original thought that I would
> purchase older 3-phase equipment and restore it for use in my workshop since
> I am unable to get 3-phase service. Primary reason for this one was
> capacity and price. I bought it used in ebay for a good price IMO.
...
OK, thanks...it's been a low-level "onna-these-here-days" for some time
now. I <eventually> want the shop in the barn loft and would like a
couple larger pieces such as a 4-side moulder and thickness sander that
could be in the present shop area where the low ceilings aren't such an
issue...haven't found that bargain as yet (but haven't really searched
seriously yet, either)...
If one should wander off to SW KS sometime and were in need of a home,
I'm sure something could be arranged... :)
Dang, Lew, I've got ONE welder I'm gonna install that the data plate says
requires a 95 amp circuit.......One of the best things I ever did was
install a 200 amp main just for my one man shop.
RJ
"Lew Hodgett" <[email protected]> wrote in message
news:[email protected]...
> DL wrote:
>> I am in the process of installing a subpanel to consolidate the wiring in
>> my workshop. The panel is rated for 150amps, but I purchased a 125 amp
>> to install in the main panel.
> <snip>
>
> For a 120/240 VAC service, a 2P-60A main kit installed in a 125 MLO, 12/24
> panel will handle everything a one man shop can throw at it.
>
> The largest motor you can run on single phase is about 5HP, cap start, cap
> run, normally found on an air compressor.
>
> A 2P-40A branch c'bkr will handle the compressor.
>
> Everything else incuding a table saw and a welder will be smaller loads.
>
> HTH
>
> Lew
"Doug Miller" <[email protected]> wrote in message
news:[email protected]...
>
> Yes, of course the whole house runs on an aluminum drop.
>
> The difference is that the service entrance almost certainly was installed
by
> a professional who has the skills and knowledge to install it correctly -
> skills and knowledge not possessed by the average homeowner.
>
> _When_properly_installed_ aluminum wiring is as safe as copper. The
trouble
> is that aluminum is much more difficult to install properly than copper
is.
> It's just plain foolish for Joe Homeowner to take chances with it.
>
While I do generally agree with what you've said about the advantages of
copper over aluminum in this whole thread Doug, I do disagree with what you
say here. There's just too many home across America that had their service
entrance installed by the home owner with absolutely no problems and no
reason to believe there will be any probles, for your assertion above to be
correct. It really does not take a professional to install a service with
aluminum wire. It really does not take any special skills or sage wisdom.
It's just a connection. The average homeowner is very capable of posessing
these skills and knowledge. Not to say that all are of course, but that'd
be another thread. Sometimes we can overly mystify this stuff.
--
-Mike-
[email protected]
In article <FWF7e.1716$H53.475@lakeread05>, "DL" <[email protected]> wrote:
>If the copper will handle the 100amp breaker I already have, then I will
>most likefully go with that.
Note that if your copper cable will *not* handle it, neither will an aluminum
cable. If using aluminum [which I do *not* recommend], you need substantially
larger conductors to have the same ampacity as copper.
To carry 100A in a 3-conductor cable, you need at minimum:
4ga copper or 2ga aluminum, conductor temp 85 deg C or higher
3ga copper or 1ga aluminum, conductor temp 75 deg C or higher
1ga copper or 2/0 aluminum, conductor temp 60 deg C or higher
[National Electrical Code, Table B-310-3]
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
"Wilson Lamb" <[email protected]> wrote in message
news:[email protected]...
> I'm betting his whole house runs on an aluminum drop to his main panel. I
> can't remember the last copper service I saw. With a big feed like that,
> no sustained heavy loads, and no connections buried in the walls, I
> wouldn't worry. But for a short run, copper might feel better, and be
> easy to handle.
> Wilson
Wilson,
The main service 200amps going to 400amps is Aluminum as you stated. Have
not had any problems with it, and I would suspect that most of the homes are
built with it as a service entrance.
Nothing buried in the walls for sure. I have been a bit obsessive on the
number of outlets to allow for easy reconfiguration down the road.
If the copper will handle the 100amp breaker I already have, then I will
most likefully go with that.
Thanks,
David
> "Doug Miller" <[email protected]> wrote in message
> news:[email protected]...
>> In article <iFD7e.1704$H53.1652@lakeread05>, "DL"
>> <[email protected]> wrote:
>>>I am in the process of installing a subpanel to consolidate the wiring in
>>>my
>>>workshop. The panel is rated for 150amps, but I purchased a 125 amp to
>>>install in the main panel. I additionally have a 100amp breaker as well.
>>>The largest bound copper cable I can get without a special order from the
>>>local electrical supply house is 2/3 which will handle up to 95amps.
>>
>> Unless the insulation is rated at only 60 deg C, a 2/3 cable ought to
>> handle a
>> lot more than 95 amps. Where are you getting that figure from?
>>
>> You can do 100A in a 4/3 cable if the conductor temperature is rated 85
>> deg C
>> or higher....
>>
>>>I would prefer not to wait for the special order if I don't have to.
>>>50amps
>>>is the next size down at the local Home Depot, ( I need to see what the
>>>electric supply house has, I assume I can get a 70, 80, or 90)
>>
>> I would think so. I'm surprised you didn't find a 60 at HD.
>>
>>>My questions are:
>>>
>>>1. I am thinking that I really don't need 100amps, so I wanted to query
>>>others to see what they have installed. (I am in the process of totally
>>>up
>>>the equipment and amps that I would expect would be needed at a given
>>>time
>>>to make sure I have all that I need, but that is not complete) I do have
>>>a
>>>fair amount of machinery and can see 2 - 3 users larger pieces of
>>>equipment
>>>plus auxillary air compressor, dust collection, air filtration, general
>>>power consumption that will add up. In my mind, it's not that much more
>>>expensive to add the extra amps at this point and would rather overplan
>>>than
>>>be under powered at a later date which would be much more expensive to
>>>upgade, if I needed it.
>>
>> You certainly have the right idea about the cost of building bigger than
>> you
>> need vs. the cost of upgrading later. But I think you're going bigger by
>> a
>> larger margin than necessary. 60A at 240V will provide more power than
>> you're
>> likely to need in a home shop.
>>
>>>2. I can purchase Aluminum to handle the 125amp's but I have heard bad
>>>things about the aluminum connection corrosion. I know I can put the
>>>special grease on the connections to prevent the corrosion. Any thoughts
>>>or
>>>comments?
>>
>> Under _no_ circumstances would I ever install an aluminum feed to a
>> subpanel
>> in my home, or advise anyone else to. It's just too risky, and for what
>> benefit? Sure, you might save a few bucks, but it's a whole lot less safe
>> than
>> copper unless it's installed _exactly_ right. Trouble is, it's a whole
>> lot
>> more difficult to install correctly than copper is. It's not just a
>> matter of
>> adding anti-oxidant compound to the connections. Bolt lugs must be
>> tightened
>> with a torque wrench, both to make sure that they are tight enough, and
>> to
>> make sure that they are not _too_ tight, because aluminum will cold-flow
>> away
>> from an overtorqued connection, loosening it, and causing it to arc. All
>> equipment used must be rated for use with aluminum. And so on.
>>
>> Don't do it. It isn't worth it.
>>
>> --
>> Regards,
>> Doug Miller (alphageek at milmac dot com)
>>
>> Nobody ever left footprints in the sands of time by sitting on his butt.
>> And who wants to leave buttprints in the sands of time?
>
>
"DL" <[email protected]> wrote in message
news:iFD7e.1704$H53.1652@lakeread05...
>I am in the process of installing a subpanel to consolidate the wiring in
>my workshop. The panel is rated for 150amps, but I purchased a 125 amp to
>install in the main panel. I additionally have a 100amp breaker as well.
>The largest bound copper cable I can get without a special order from the
>local electrical supply house is 2/3 which will handle up to 95amps. I
>would prefer not to wait for the special order if I don't have to. 50amps
>is the next size down at the local Home Depot, ( I need to see what the
>electric supply house has, I assume I can get a 70, 80, or 90)
>
> My questions are:
>
> 1. I am thinking that I really don't need 100amps, so I wanted to query
> others to see what they have installed. (I am in the process of totally up
> the equipment and amps that I would expect would be needed at a given time
> to make sure I have all that I need, but that is not complete) I do have
> a fair amount of machinery and can see 2 - 3 users larger pieces of
> equipment plus auxillary air compressor, dust collection, air filtration,
> general power consumption that will add up. In my mind, it's not that
> much more expensive to add the extra amps at this point and would rather
> overplan than be under powered at a later date which would be much more
> expensive to upgade, if I needed it.
>
> 2. I can purchase Aluminum to handle the 125amp's but I have heard bad
> things about the aluminum connection corrosion. I know I can put the
> special grease on the connections to prevent the corrosion. Any thoughts
> or comments?
>
> David
>
Just spoke with the county and they will approve up to 115amps on 2/3 with
ground. With the rotary phase converter requiring a 70-80amp breaker, and
since I already have a 100amp breaker, that is what I plan to go with. The
extra cost in wire is offset by it being able to handle the smaller loads
better and I won't have to upgrade in the future.
Thanks to all that responded.
David
I'm betting his whole house runs on an aluminum drop to his main panel. I
can't remember the last copper service I saw. With a big feed like that, no
sustained heavy loads, and no connections buried in the walls, I wouldn't
worry. But for a short run, copper might feel better, and be easy to
handle.
Wilson
"Doug Miller" <[email protected]> wrote in message
news:[email protected]...
> In article <iFD7e.1704$H53.1652@lakeread05>, "DL"
> <[email protected]> wrote:
>>I am in the process of installing a subpanel to consolidate the wiring in
>>my
>>workshop. The panel is rated for 150amps, but I purchased a 125 amp to
>>install in the main panel. I additionally have a 100amp breaker as well.
>>The largest bound copper cable I can get without a special order from the
>>local electrical supply house is 2/3 which will handle up to 95amps.
>
> Unless the insulation is rated at only 60 deg C, a 2/3 cable ought to
> handle a
> lot more than 95 amps. Where are you getting that figure from?
>
> You can do 100A in a 4/3 cable if the conductor temperature is rated 85
> deg C
> or higher....
>
>>I would prefer not to wait for the special order if I don't have to.
>>50amps
>>is the next size down at the local Home Depot, ( I need to see what the
>>electric supply house has, I assume I can get a 70, 80, or 90)
>
> I would think so. I'm surprised you didn't find a 60 at HD.
>
>>My questions are:
>>
>>1. I am thinking that I really don't need 100amps, so I wanted to query
>>others to see what they have installed. (I am in the process of totally up
>>the equipment and amps that I would expect would be needed at a given time
>>to make sure I have all that I need, but that is not complete) I do have
>>a
>>fair amount of machinery and can see 2 - 3 users larger pieces of
>>equipment
>>plus auxillary air compressor, dust collection, air filtration, general
>>power consumption that will add up. In my mind, it's not that much more
>>expensive to add the extra amps at this point and would rather overplan
>>than
>>be under powered at a later date which would be much more expensive to
>>upgade, if I needed it.
>
> You certainly have the right idea about the cost of building bigger than
> you
> need vs. the cost of upgrading later. But I think you're going bigger by a
> larger margin than necessary. 60A at 240V will provide more power than
> you're
> likely to need in a home shop.
>
>>2. I can purchase Aluminum to handle the 125amp's but I have heard bad
>>things about the aluminum connection corrosion. I know I can put the
>>special grease on the connections to prevent the corrosion. Any thoughts
>>or
>>comments?
>
> Under _no_ circumstances would I ever install an aluminum feed to a
> subpanel
> in my home, or advise anyone else to. It's just too risky, and for what
> benefit? Sure, you might save a few bucks, but it's a whole lot less safe
> than
> copper unless it's installed _exactly_ right. Trouble is, it's a whole lot
> more difficult to install correctly than copper is. It's not just a matter
> of
> adding anti-oxidant compound to the connections. Bolt lugs must be
> tightened
> with a torque wrench, both to make sure that they are tight enough, and to
> make sure that they are not _too_ tight, because aluminum will cold-flow
> away
> from an overtorqued connection, loosening it, and causing it to arc. All
> equipment used must be rated for use with aluminum. And so on.
>
> Don't do it. It isn't worth it.
>
> --
> Regards,
> Doug Miller (alphageek at milmac dot com)
>
> Nobody ever left footprints in the sands of time by sitting on his butt.
> And who wants to leave buttprints in the sands of time?
DL wrote:
> I am in the process of installing a subpanel to consolidate the wiring in my
> workshop. The panel is rated for 150amps, but I purchased a 125 amp to
> install in the main panel. I additionally have a 100amp breaker as well.
> The largest bound copper cable I can get without a special order from the
> local electrical supply house is 2/3 which will handle up to 95amps. I
> would prefer not to wait for the special order if I don't have to. 50amps
> is the next size down at the local Home Depot, ( I need to see what the
> electric supply house has, I assume I can get a 70, 80, or 90)
>
> My questions are:
>
> 1. I am thinking that I really don't need 100amps, so I wanted to query
> others to see what they have installed. (I am in the process of totally up
> the equipment and amps that I would expect would be needed at a given time
> to make sure I have all that I need, but that is not complete) I do have a
> fair amount of machinery and can see 2 - 3 users larger pieces of equipment
> plus auxillary air compressor, dust collection, air filtration, general
> power consumption that will add up. In my mind, it's not that much more
> expensive to add the extra amps at this point and would rather overplan than
> be under powered at a later date which would be much more expensive to
> upgade, if I needed it.
>
> 2. I can purchase Aluminum to handle the 125amp's but I have heard bad
> things about the aluminum connection corrosion. I know I can put the
> special grease on the connections to prevent the corrosion. Any thoughts or
> comments?
>
> David
>
>
I run my shop 24'x40' on 80 amps. It's 175' from the main panel running
on 3 #4's and a #6. I could have used less but I had the breaker. If
it's a one man shop then anything over I think would be overkill.
All I would say is stay away from aluminum, even if it's just for a feed.
In article <rtP7e.443$lz1.234@lakeread01>, "DL" <[email protected]> wrote:
>The cost difference isn't that much so I would rather go with the heavier
>wire. As for the bends, I am lucky that the routing of the wire has just a
>few bends in it that can be done at a gentle curve. Once I find out wire
>temp rating and what Amps the county will approve on rated 2/3, I plan to go
>with the 2/3 and buy the the highest amp breaker if the 100 or 125 are too
>much. Hopefully they will approve the at least the 100amp. This will
>cover me for anything I have.
>
>Thanks for the help,
You're welcome. You did catch the part about needing three conductors PLUS
ground (below), right?
>> One thing I meant to mention in my first response to you, that I think I
>> omitted: make sure that the cable you use to feed the subpanel has a
>> grounding conductor. You need 2/3 WG (With Ground), not just 2/3. In the subpanel,
>> the equipment grounding bus bar and the neutral bus bar must *not* be
>> connected.
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
In article <iFD7e.1704$H53.1652@lakeread05>, "DL" <[email protected]> wrote:
>I am in the process of installing a subpanel to consolidate the wiring in my
>workshop. The panel is rated for 150amps, but I purchased a 125 amp to
>install in the main panel. I additionally have a 100amp breaker as well.
>The largest bound copper cable I can get without a special order from the
>local electrical supply house is 2/3 which will handle up to 95amps.
Unless the insulation is rated at only 60 deg C, a 2/3 cable ought to handle a
lot more than 95 amps. Where are you getting that figure from?
You can do 100A in a 4/3 cable if the conductor temperature is rated 85 deg C
or higher....
>I would prefer not to wait for the special order if I don't have to. 50amps
>is the next size down at the local Home Depot, ( I need to see what the
>electric supply house has, I assume I can get a 70, 80, or 90)
I would think so. I'm surprised you didn't find a 60 at HD.
>My questions are:
>
>1. I am thinking that I really don't need 100amps, so I wanted to query
>others to see what they have installed. (I am in the process of totally up
>the equipment and amps that I would expect would be needed at a given time
>to make sure I have all that I need, but that is not complete) I do have a
>fair amount of machinery and can see 2 - 3 users larger pieces of equipment
>plus auxillary air compressor, dust collection, air filtration, general
>power consumption that will add up. In my mind, it's not that much more
>expensive to add the extra amps at this point and would rather overplan than
>be under powered at a later date which would be much more expensive to
>upgade, if I needed it.
You certainly have the right idea about the cost of building bigger than you
need vs. the cost of upgrading later. But I think you're going bigger by a
larger margin than necessary. 60A at 240V will provide more power than you're
likely to need in a home shop.
>2. I can purchase Aluminum to handle the 125amp's but I have heard bad
>things about the aluminum connection corrosion. I know I can put the
>special grease on the connections to prevent the corrosion. Any thoughts or
>comments?
Under _no_ circumstances would I ever install an aluminum feed to a subpanel
in my home, or advise anyone else to. It's just too risky, and for what
benefit? Sure, you might save a few bucks, but it's a whole lot less safe than
copper unless it's installed _exactly_ right. Trouble is, it's a whole lot
more difficult to install correctly than copper is. It's not just a matter of
adding anti-oxidant compound to the connections. Bolt lugs must be tightened
with a torque wrench, both to make sure that they are tight enough, and to
make sure that they are not _too_ tight, because aluminum will cold-flow away
from an overtorqued connection, loosening it, and causing it to arc. All
equipment used must be rated for use with aluminum. And so on.
Don't do it. It isn't worth it.
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
"Doug Miller" <[email protected]> wrote in message
news:[email protected]...
> In article <rtP7e.443$lz1.234@lakeread01>, "DL"
> <[email protected]> wrote:
>
>>The cost difference isn't that much so I would rather go with the heavier
>>wire. As for the bends, I am lucky that the routing of the wire has just
>>a
>>few bends in it that can be done at a gentle curve. Once I find out wire
>>temp rating and what Amps the county will approve on rated 2/3, I plan to
>>go
>>with the 2/3 and buy the the highest amp breaker if the 100 or 125 are too
>>much. Hopefully they will approve the at least the 100amp. This will
>>cover me for anything I have.
>>
>>Thanks for the help,
>
> You're welcome. You did catch the part about needing three conductors PLUS
> ground (below), right?
>
Doug,
Yes I did, it's 2/3 with ground, and I do understand that the neutral and
ground bars are not to be connected in the subpanel as the are in the main
panel.
Thanks again,
David
>>> One thing I meant to mention in my first response to you, that I think I
>>> omitted: make sure that the cable you use to feed the subpanel has a
>>> grounding conductor. You need 2/3 WG (With Ground), not just 2/3. In the
>>> subpanel,
>>> the equipment grounding bus bar and the neutral bus bar must *not* be
>>> connected.
>
> --
> Regards,
> Doug Miller (alphageek at milmac dot com)
>
> Nobody ever left footprints in the sands of time by sitting on his butt.
> And who wants to leave buttprints in the sands of time?
In article <[email protected]>, "Wilson Lamb" <[email protected]> wrote:
>I'm betting his whole house runs on an aluminum drop to his main panel. I
>can't remember the last copper service I saw. With a big feed like that, no
>sustained heavy loads, and no connections buried in the walls, I wouldn't
>worry. But for a short run, copper might feel better, and be easy to
>handle.
>Wilson
Yes, of course the whole house runs on an aluminum drop.
The difference is that the service entrance almost certainly was installed by
a professional who has the skills and knowledge to install it correctly -
skills and knowledge not possessed by the average homeowner.
_When_properly_installed_ aluminum wiring is as safe as copper. The trouble
is that aluminum is much more difficult to install properly than copper is.
It's just plain foolish for Joe Homeowner to take chances with it.
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
DL wrote:
> I am in the process of installing a subpanel to consolidate the wiring in my
> workshop. The panel is rated for 150amps, but I purchased a 125 amp to
> install in the main panel.
<snip>
For a 120/240 VAC service, a 2P-60A main kit installed in a 125 MLO,
12/24 panel will handle everything a one man shop can throw at it.
The largest motor you can run on single phase is about 5HP, cap start,
cap run, normally found on an air compressor.
A 2P-40A branch c'bkr will handle the compressor.
Everything else incuding a table saw and a welder will be smaller loads.
HTH
Lew
"Fly-by-Night CC" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>,
> "Swingman" <[email protected]> wrote:
>
>> > Lew,
>> >
>> > Thanks for the input.
>>
>> Take Lew's advice to heart and follow it ... I wired my shop according to
>> his suggestions a few years back and have not regretted it. Best advice I
>> ever got in exchange for a recipe, IIRC. ;)
>
> And DL when you get to the point of installing new lighting, do a
> newsgroup google search with Lew's name as author - I followed his
> advice and am quite pleased with the brightness in my shop.
> --
> Owen Lowe
> The Fly-by-Night Copper Company
> ____
Thanks, it is next on my list...
David
>
> "I pledge allegiance to the flag of the
> Corporate States of America and to the
> Republicans for which it stands, one nation,
> under debt, easily divisible, with liberty
> and justice for oil."
> - Wiley Miller, Non Sequitur, 1/24/05
"Lew Hodgett" <[email protected]> wrote in message
news:[email protected]...
> DL wrote:
>> I am in the process of installing a subpanel to consolidate the wiring in
>> my workshop. The panel is rated for 150amps, but I purchased a 125 amp
>> to install in the main panel.
> <snip>
>
> For a 120/240 VAC service, a 2P-60A main kit installed in a 125 MLO, 12/24
> panel will handle everything a one man shop can throw at it.
>
> The largest motor you can run on single phase is about 5HP, cap start, cap
> run, normally found on an air compressor.
>
> A 2P-40A branch c'bkr will handle the compressor.
>
> Everything else incuding a table saw and a welder will be smaller loads.
>
> HTH
>
> Lew
Lew,
Thanks for the input.
David
"Duane Bozarth" <[email protected]> wrote in message
news:[email protected]...
> DL wrote:
> ...
>> ... With the rotary phase converter requiring a 70-80amp breaker, ...
>
> Just out of curiousity, whose converter did you go with and reasons for
> the particular choice???
Duane,
I will have to get the information on the brand (I think S&S) for you as it
is stored currently while I am doing the buildout. The unit has a 7.5hp
Baldor motor that I purchased based on an original thought that I would
purchase older 3-phase equipment and restore it for use in my workshop since
I am unable to get 3-phase service. Primary reason for this one was
capacity and price. I bought it used in ebay for a good price IMO.
I am rethinking the need for the rotary phase converter at my current
location. Having a somewhat longer term goal to move where I should be able
to get the 3 phase power brought in directly into a dedicated workshop
building, I will hold off on purchasing anymore 3 phase equipment. For the
3 phase lathe I have, I am strongly considering moving to a variable
frequency drive that will convert the single to 3 phase, thus obviating my
current need for the phase converter at all. The rotary phase converter I
have not is way over spec for the lathe alone, but wouldn't be for a 7.5hp
DeWalt RAS or other larger machinery that I want to delve into at some
point.
David
Lugs on panels and breakers are either rated copper only, or copper
and aluminum. If you use aluminum wire make sure the lugs on the
panel or breaker specifically are rated for aluminum.
It'll never hurt to oversize the wire. Larger sizes will lower the
voltage drop over distance.
If you are at all unsure, hire an electrician, or get advice from one.
I would not count on advice from your electrical supplier, any HD
employee, or even reccomendations for well meaning and mostly
intellegent members of this group.
my $0.02.
Alan
In article <[email protected]>,
"Swingman" <[email protected]> wrote:
> > Lew,
> >
> > Thanks for the input.
>
> Take Lew's advice to heart and follow it ... I wired my shop according to
> his suggestions a few years back and have not regretted it. Best advice I
> ever got in exchange for a recipe, IIRC. ;)
And DL when you get to the point of installing new lighting, do a
newsgroup google search with Lew's name as author - I followed his
advice and am quite pleased with the brightness in my shop.
--
Owen Lowe
The Fly-by-Night Copper Company
____
"I pledge allegiance to the flag of the
Corporate States of America and to the
Republicans for which it stands, one nation,
under debt, easily divisible, with liberty
and justice for oil."
- Wiley Miller, Non Sequitur, 1/24/05
"Doug Miller" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, "Mike Marlow"
> <[email protected]> wrote:
>
>>While I do generally agree with what you've said about the advantages of
>>copper over aluminum in this whole thread Doug, I do disagree with what
>>you
>>say here. There's just too many home across America that had their
>>service
>>entrance installed by the home owner with absolutely no problems and no
>>reason to believe there will be any probles, for your assertion above to
>>be
>>correct. It really does not take a professional to install a service with
>>aluminum wire. It really does not take any special skills or sage wisdom.
>
> I'm sorry, but that's not true, not completely, anyway. No, it doesn't
> require
> a professional to install aluminum wire [and I did not say that it did],
> but
> it *does* require special knowledge, if not special skills, and tools that
> are
> not in the average homeowner's toolbox.
>
> To install aluminum safely, connections must be coated with anti-oxidant
> compound. This is not necessary with copper. And not everyone knows about
> the
> difference.
>
> Lugs holding aluminum wire must be tightened to a specific torque. Too
> loose,
> and the wire arcs, or comes out - but too tight, and it cold-flows away,
> and
> arcs. Again, not everyone knows this. And the average homeowner does not
> have
> a torque wrench in his toolbox.
>
>>It's just a connection.
>
> No, it's *not* "just a connection". It's a connection that needs to be
> made
> with substantially more care than connections involving copper wire. And
> not
> everybody knows this.
>
>>The average homeowner is very capable of posessing
>>these skills and knowledge.
>
> I never said that the average homeowner was not *capable* of possessing
> the
> requisite skills and knowledge. I do claim, though, that the average
> homeowner
> possesses neither those skills, nor a torque wrench.
>
I agree with Mike that it is not a overly complex connection to install as
long as someone has the proper knowledge, tools, and respect for the
potential dangers of not doing it correctly. I also agree with Doug that
the are inherent issues with the Al connection that don't arise with the
copper installation. When I added an addition on our old house, I needed to
redo a significant amount of the wiring the previous owner did when he added
a small addition on the house because it was installed wrong.
Also, the fact that I would need to go to #00 Al to get the same load
capacity, it as the #2 copper, going with the cooper will just be easier to
handle when I am routing the cable from the main to the subpanel.
It's great to know that I am not an average "Joe" homeowner. Not only do I
have a torque wrench and know how to use it, I have three of varing sizes :D
David
>>Not to say that all are of course, but that'd
>>be another thread. Sometimes we can overly mystify this stuff.
>
> I'm not trying to make mysteries out of anything. Just pointing out that
> installing aluminum wire correctly is not as simple as installing copper
> wire
> correctly - and since *any* incorrectly installed wiring presents
> potentially
> lethal hazards, Joe Homeowner is better off using copper simply because
> it's
> harder to screw up.
>
>
> --
> Regards,
> Doug Miller (alphageek at milmac dot com)
>
> Nobody ever left footprints in the sands of time by sitting on his butt.
> And who wants to leave buttprints in the sands of time?
"Doug Miller" <[email protected]> wrote in message
news:[email protected]...
> In article <2SF7e.1714$H53.1103@lakeread05>, "DL"
> <[email protected]> wrote:
>
>>Given that I have already have the 100 and 125amp breakers for the main
>>panel which I would prefer to use, the cost difference in the wire is
>>minimal given that we are talking < 50' distance.
>
> Well, it's not just the cost. Heavy cables are a PITA to work with. They
> don't
> bend easily.
>
The cost difference isn't that much so I would rather go with the heavier
wire. As for the bends, I am lucky that the routing of the wire has just a
few bends in it that can be done at a gentle curve. Once I find out wire
temp rating and what Amps the county will approve on rated 2/3, I plan to go
with the 2/3 and buy the the highest amp breaker if the 100 or 125 are too
much. Hopefully they will approve the at least the 100amp. This will
cover me for anything I have.
Thanks for the help,
David
> One thing I meant to mention in my first response to you, that I think I
> omitted: make sure that the cable you use to feed the subpanel has a
> grounding
> conductor. You need 2/3 WG (With Ground), not just 2/3. In the subpanel,
> the
> equipment grounding bus bar and the neutral bus bar must *not* be
> connected.
>
>> If I am correct, just
>>like the main panel at 200amps, if you only put one 20amp breaker in,
>>there
>>won't be a problem having too many amps being fed into the subpanel, the
>>equipment will draw the necessary power it needs from the individual
>>breakers in the subpanel.
>
> Yes, that's correct.
>
>>This does go to the point of equipment overload. If I have a piece of
>>equipment that draws 25amps and have a circuit consisting of a 50amp
>>circuit
>>breaker, 6/3 wire from the breaker to the outlet, and a 50 amp outlet, I
>>should still be fine, isn't the logic the same? or do I need to worry
>>about
>>overloading the equipment. It has always been my understanding that
>>equipment / motors draw the power they need from a circuit. The breaker
>>is
>>designed to kick off when too much current is required thus causing a
>>situation where the wire would heat up and become unsafe. (goes to your
>>temp rating statement above)
>
> Your understanding is correct: the equipment draws the power it needs. The
> purpose of the circuit breaker is to protect the wiring and the
> receptacle,
> *not* what's plugged into the receptacle.
>
>>Also, the rotary phase converter I have requires 70-80amp breaker IIRC (I
>>have to get with the manufacturer to confirm), though I am not exactly
>>sure
>>why a 7.5hp 3 phase motor requires that much. I would figure that while
>>it
>>doesn't draw those amps all the time, it is needed at some point, possibly
>>startup.
>
> I think you have that right, too.
>
> --
> Regards,
> Doug Miller (alphageek at milmac dot com)
>
> Nobody ever left footprints in the sands of time by sitting on his butt.
> And who wants to leave buttprints in the sands of time?
both home depot and lowes have mobile home feed cable. rated at 150
amps, i believe, capable of being buried without a conduit. sizes i
forget. it is actually 3 wires (2 aluminum and 1 copper, i believe)
twisted together. locally it runs $1.28 to $1.50 per foot. of course
installation above ground should have appropriate sized conduit where
contact could be made
On Mon, 18 Apr 2005 14:52:52 -0000, Brian Elfert <[email protected]>
wrote:
>"DL" <[email protected]> writes:
>
>>I am in the process of installing a subpanel to consolidate the wiring in my
>>workshop. The panel is rated for 150amps, but I purchased a 125 amp to
>
>I installed 100 amps, but I doubt I'll ever need that much. I could
>envision the 220V dust collector, 220V Unisaw, and the 220V air compressor
>all running at once, but they would take 40 amps or less.
>
>>install in the main panel. I additionally have a 100amp breaker as well.
>>The largest bound copper cable I can get without a special order from the
>>local electrical supply house is 2/3 which will handle up to 95amps. I
>>would prefer not to wait for the special order if I don't have to. 50amps
>>is the next size down at the local Home Depot, ( I need to see what the
>>electric supply house has, I assume I can get a 70, 80, or 90)
>
>My local Home Depot has wire plenty big enough to handle 100 amps. It is
>THHN and has to be run in a conduit. I used three seperate wires to feed
>my subpanel.
>
>Brian Elfert
In article <[email protected]>, "Mike Marlow" <[email protected]> wrote:
>While I do generally agree with what you've said about the advantages of
>copper over aluminum in this whole thread Doug, I do disagree with what you
>say here. There's just too many home across America that had their service
>entrance installed by the home owner with absolutely no problems and no
>reason to believe there will be any probles, for your assertion above to be
>correct. It really does not take a professional to install a service with
>aluminum wire. It really does not take any special skills or sage wisdom.
I'm sorry, but that's not true, not completely, anyway. No, it doesn't require
a professional to install aluminum wire [and I did not say that it did], but
it *does* require special knowledge, if not special skills, and tools that are
not in the average homeowner's toolbox.
To install aluminum safely, connections must be coated with anti-oxidant
compound. This is not necessary with copper. And not everyone knows about the
difference.
Lugs holding aluminum wire must be tightened to a specific torque. Too loose,
and the wire arcs, or comes out - but too tight, and it cold-flows away, and
arcs. Again, not everyone knows this. And the average homeowner does not have
a torque wrench in his toolbox.
>It's just a connection.
No, it's *not* "just a connection". It's a connection that needs to be made
with substantially more care than connections involving copper wire. And not
everybody knows this.
>The average homeowner is very capable of posessing
>these skills and knowledge.
I never said that the average homeowner was not *capable* of possessing the
requisite skills and knowledge. I do claim, though, that the average homeowner
possesses neither those skills, nor a torque wrench.
>Not to say that all are of course, but that'd
>be another thread. Sometimes we can overly mystify this stuff.
I'm not trying to make mysteries out of anything. Just pointing out that
installing aluminum wire correctly is not as simple as installing copper wire
correctly - and since *any* incorrectly installed wiring presents potentially
lethal hazards, Joe Homeowner is better off using copper simply because it's
harder to screw up.
--
Regards,
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?