Greetings All!
I am in the process of wiring up a shed in the backyard for use as a
workshop. I have a new SquareD load center panel (QO8-16L100S) that I
want to use but need some clarification.
1. This particular panel only has one grounding/neutral bar, but I was
under the impression the ground and neutral must be separated in a
subpanel installed in a stand alone structure. Should I just buy a
ground bar and install it in the panel and connect it to a new
grounding rod?
2. The panel is rated for 100A, but I was hoping to use a 60A-75A
breaker in the main box to feed this subpanel. Is this a problem? The
subpanel does not have a main breaker in it.
3. The run from the main panel to the sub will only be about 15 ft.
total. What size wire do you suggest I run?
Thanks,
Robb
Robert Bonomi wrote:
> Lew Hodgett <[email protected]> wrote:
>
>>Somebody wrote:
>>
>>
>>>NEC requires a main for more than 6 breakers.
>>
>>
>>TRUE.
>
>
> FALSE!
>
>
>>Known in some circles as the "6 hand" rule.
>>
>>Regardless of whether a panel is a "sub" or a "main", you must be able
>>to disconnect ALL power distributed by that panel in a maximum of 6
>>motions of the hand.
>
>
> I -wanted- a master-cut-off in the main breaker panel in my condo
> when I was rebuilding the kitchen, and replacing the breaker panel.
> (went from 14 to 20 circuits, original panel mfr long out of business,
> had to enclosure, et al.)
>
> City inspector would not allow a 100A breaker at panel feed, because
> there was 100A breaker (only) panel in utility entry room.
>
> I had, per inspector, choice of:
> 1) run with *no* 'master-cut-off breaker' in unit.
> 2) try to find something like a 95A breaker to use as the 'main'
> in unit.
> 3) replace (obsolete, mfr out-of-business) breaker at utility entry
> room with something like 110A,, and use 100A in unit.
>
> "1" was the only 'financially viable' alternative.
>
I'm not sure I understand your explanation; however, the "6 hand rule"
applies if you are going to comply with NEC.
Got any idea what this "inspector" had for a day job?
Lew
>1. This particular panel only has one grounding/neutral bar, but I was
>under the impression the ground and neutral must be separated in a
>subpanel installed in a stand alone structure. Should I just buy a
>ground bar and install it in the panel and connect it to a new
>grounding rod?
I'll defer to others on this one. The conduit should serve as a ground,
but some placed might require a separate ground wire.
>2. The panel is rated for 100A, but I was hoping to use a 60A-75A
>breaker in the main box to feed this subpanel. Is this a problem? The
>subpanel does not have a main breaker in it.
I did exactly this. It's not a problem since the breaker protects the
wire.
>3. The run from the main panel to the sub will only be about 15 ft.
>total. What size wire do you suggest I run?
Size it to match the breaker you put in the main panel. You'll need
something like #8 or #6 for 60 amps. I can't remember what I used. It
will be disasterous if you size it too small.
brian
Thanks to all for the quick responses. This was the exact info I was
looking for. Now I'm off to see if home depot or lowe's carry #4
wire...
robb
[email protected] wrote:
> On 19 Apr 2006 08:44:42 -0700, [email protected] wrote:
>
> > 1. This particular panel only has one grounding/neutral bar, but I was
> >under the impression the ground and neutral must be separated in a
> >subpanel installed in a stand alone structure. Should I just buy a
> >ground bar and install it in the panel and connect it to a new
> >grounding rod?
> Yes and do not install the jumper/green screw that would bond the
> neutral bar. Run a 4 wire feeder.
>
>
> > 2. The panel is rated for 100A, but I was hoping to use a 60A-75A
> >breaker in the main box to feed this subpanel. Is this a problem? The
> >subpanel does not have a main breaker in it.
> That is OK if you have less than 6 breakers in the sub.
>
> > 3. The run from the main panel to the sub will only be about 15 ft.
> >total. What size wire do you suggest I run?
>
> 4 ga copper is a good choice. That gets you up to 85a
> The ground wire can be #8 copper up to 100a
Thank you for the detailed reply, Scott.
Scott Lurndal wrote:
> [email protected] writes:
> >Greetings All!
> >
> >I am in the process of wiring up a shed in the backyard for use as a
> >workshop. I have a new SquareD load center panel (QO8-16L100S) that I
> >want to use but need some clarification.
> > 1. This particular panel only has one grounding/neutral bar, but I was
> >under the impression the ground and neutral must be separated in a
> >subpanel installed in a stand alone structure. Should I just buy a
> >ground bar and install it in the panel and connect it to a new
> >grounding rod?
>
> First, remove the bonding screw that bonds the grounded (neutral)
> busbar to the enclosure. Second, purchase an accessory busbar and
> fasten it to the enclosure as the grounding busbar. Third, bond the
> grounding busbar in the subpanel to the grounding busbar in the
> service entrance with the appropriate gauge green/bare conductor. You'll
> also want to bond the grounded busbar in the subpanel to the grounded
> busbar in the service entrance panel with suitably sized white conductor.
I should also use the bonding screw for the grounding busbar, right?
<snip>
> > 3. The run from the main panel to the sub will only be about 15 ft.
> >total. What size wire do you suggest I run?
>
> If you use a 60A breaker, #6 should be sufficient at that length. Check
> the NEC tables for definitive value based upon your conductor temperature
> rating.
>
> Are you using conduit and a thermoplastic insulated 90 degree-rated conductor
> such as THHN or #6/3 w/g jacketed (which IIRC are 60 degree-rated conductors)?
I was planning on burying with PVC type conduit and running #6/3
w/g...assuming I can find that wire. Sounds good?
Robb
No - you should run 4 - two hots, a neutral and a ground.
Because the cost difference isn't much, I'd recommend you go with #4 in
case you ever want to upgrade from the 60A to 100A. Also, be sure to
use large enough conduit (probably 2") so that you don't overfill.
Lots of other good responses here.
Lastly, do talk to your electrical inspector - not only is it the law
(almost everywhere) but it means you'll have a safe install and you
won't be on the line if your house burns down and it is traced back to
your work! Our local inspector is very helpful and is happy to help
DIY'ers.
stormy2084 wrote:
> No - you should run 4 - two hots, a neutral and a ground.
>
> Because the cost difference isn't much, I'd recommend you go with #4 in
> case you ever want to upgrade from the 60A to 100A. Also, be sure to
> use large enough conduit (probably 2") so that you don't overfill.
> Lots of other good responses here.
You're right, I should go with the bigger stuff. Is wire this large
available at the "usual" places?
>
> Lastly, do talk to your electrical inspector - not only is it the law
> (almost everywhere) but it means you'll have a safe install and you
> won't be on the line if your house burns down and it is traced back to
> your work! Our local inspector is very helpful and is happy to help
> DIY'ers.
How do you normally contact the local inspector?
In article <[email protected]>,
Lew Hodgett <[email protected]> wrote:
>Somebody wrote:
>
> >NEC requires a main for more than 6 breakers.
>
>
>TRUE.
FALSE!
>Known in some circles as the "6 hand" rule.
>
>Regardless of whether a panel is a "sub" or a "main", you must be able
>to disconnect ALL power distributed by that panel in a maximum of 6
>motions of the hand.
I -wanted- a master-cut-off in the main breaker panel in my condo
when I was rebuilding the kitchen, and replacing the breaker panel.
(went from 14 to 20 circuits, original panel mfr long out of business,
had to enclosure, et al.)
City inspector would not allow a 100A breaker at panel feed, because
there was 100A breaker (only) panel in utility entry room.
I had, per inspector, choice of:
1) run with *no* 'master-cut-off breaker' in unit.
2) try to find something like a 95A breaker to use as the 'main'
in unit.
3) replace (obsolete, mfr out-of-business) breaker at utility entry
room with something like 110A,, and use 100A in unit.
"1" was the only 'financially viable' alternative.
In article <[email protected]>,
Lew Hodgett <[email protected]> wrote:
>Robert Bonomi wrote:
>
> > Lew Hodgett <[email protected]> wrote:
> >
> >>Somebody wrote:
> >>
> >>
> >>>NEC requires a main for more than 6 breakers.
> >>
> >>
> >>TRUE.
> >
> >
> > FALSE!
> >
> >
> >>Known in some circles as the "6 hand" rule.
> >>
> >>Regardless of whether a panel is a "sub" or a "main", you must be able
> >>to disconnect ALL power distributed by that panel in a maximum of 6
> >>motions of the hand.
> >
> >
> > I -wanted- a master-cut-off in the main breaker panel in my condo
> > when I was rebuilding the kitchen, and replacing the breaker panel.
> > (went from 14 to 20 circuits, original panel mfr long out of business,
> > had to enclosure, et al.)
> >
> > City inspector would not allow a 100A breaker at panel feed, because
> > there was 100A breaker (only) panel in utility entry room.
> >
> > I had, per inspector, choice of:
> > 1) run with *no* 'master-cut-off breaker' in unit.
> > 2) try to find something like a 95A breaker to use as the 'main'
> > in unit.
> > 3) replace (obsolete, mfr out-of-business) breaker at utility entry
> > room with something like 110A,, and use 100A in unit.
> >
> > "1" was the only 'financially viable' alternative.
> >
>I'm not sure I understand your explanation;
Doing electrical rework, _with_ a city permit, it was specified _by_the_
city_ that I was to use a sub-panel (24 circuit capacity) *WITHOUT* a main
breaker in it. Because the main breaker was in the panel in the building
utility room.
I _wanted_ a master-cut-off in the sub-panel, but there was no =feasible=
way to do it *and* be code compliant. Since it was _not_ required by
code, I ended up going without it.
Note: *NONE* of the 30-plus units in my condo building has a master-
cut-off in the 'in unit' sub-panel. All have at least 14 circuits, and it
is comparatively 'modern' construction -- circa 35 years old.
> however, the "6 hand rule"
>applies if you are going to comply with NEC.
"Cite please". It was established in another sub-thread that that 6-breaker
max w/o a main cut-off applied to a 'service entrance' panel only. They
even quoted the relevant NEC section. Now, the question is, can you back
up -your- claim.`
Note: the person posting the NEC section showing 'service entrance' only
was someone who had made the same assentation you did, and was admitting
he had been wrong.
>
>Got any idea what this "inspector" had for a day job?
Yeah, he was the CHIEF ELECTRICAL INSPECTOR for the city, and department
head. 25+ years on the job.
He was a 'good guy' -- out of six 'somewhat unconventional' things I wanted
to do, he found code interpretations (and provided 'chapter and verse' just-
ifications) that let me DO five of them. (Just one of which saved me the
cost of at least 2 electricians for a full day, and, incidentally, around
$200 in parts.) It was only the master-cut-off that didn't fly. to be
'code compliant', I could go _without_ a master-cut-off in the sub-panel, or
I could use one that had to be _smaller_ than the main breaker downstairs.
(this required either a 'nonstandard' capacity breaker upstairs, or replacing
the one downstairs with a bigger standard value. Neither of those options was
financially viable, albeit for different reasons.)
To this day, I don't understand the 'smaller breaker' requirement. If I've
got a 100A breaker on each end of a 100+A-capable wire, "at least" one will
trip on an overload. There's no safety issue. The inspector agreed with
my logic, but said that, nonetheless, the code didn't allow it. So, I went
the 'code compliant' -- no main breaker in the sub-panel way. 22 circuits.
In article <[email protected]>,
Lew Hodgett <[email protected]> wrote:
>Robert Bonomi wrote:
>
> > "Cite please". It was established in another sub-thread that that
>6-breaker
> > max w/o a main cut-off applied to a 'service entrance' panel only. They
> > even quoted the relevant NEC section. Now, the question is, can you back
> > up -your- claim.`
> >
> > Note: the person posting the NEC section showing 'service entrance' only
> > was someone who had made the same assentation you did, and was admitting
> > he had been wrong.
>
>
>No longer have access to a current code book.
>
>My comment was based on being bloodied from having to work with local
>inspectors and contractors as a distribution equipment supplier for
>about 15 years.
>
>Your description of your experience is certainly strange.
>
>Just curious, was the main C/B visible from the distribution pnl in
>question?
Well, if you could see out the door or the condo, across the hall,
down three flights of stairs, through the laundry room and into the
utility room, then yeah, you could claim it was visible. <grin>
Now, I was straight across the hall from the stairwell, the folks
at the far end of the floor had a somewhat more obscured line of sight.
In article <[email protected]>,
Mike M <[email protected]> wrote:
>I suspect he is being impacted by local rules.
There was hardly anything in the municipal code that modified in any way
the National code.
There was an addition that _any_ new (addition or replacement) panel had
to be inspected by the city, and something else equally earth-shaking. :)
> I have used main
>breaker panels as sub panels when they are located a long ways from
>the main. I don't usually as cost of a 3 phase 208 volt 200 amp
>breaker adds quite an expense. Also since we usually have to protect
>according to available fault current fuses get a lot more practicle.
>I don't think NEC prohibits it. Feeders have to be protected where
>they are powered from unless using the tap rules.
Yup. And there is apparently a requirement that _if_ there is a breaker
at the 'downstream' End of the feeder, it must be smaller than the one at
the 'powered from' end. which meant if I wanted to use a 100A 2-pole
in the in-unit panel, I had to have 'something bigger' at the feed end.
But, the building was built (1960s) using "Federal" breakers/panels, etc.
finding 'standard' replacements is an exercise in futility -- let alone
trying to find, say, a 125A one. the other option was to put something
'a little smaller' than 100A in the in-unit panel. It's amazing how scarce
'residential style' breakers are with ratings above 60A, and below 100A.
and how _expensive_ something like a 95A breaker of that ilk is.
In article <[email protected]>,
Mike M <[email protected]> wrote:
>On Sun, 23 Apr 2006 16:19:53 -0000, [email protected]
>(Robert Bonomi) wrote:
>
>>In article <[email protected]>,
>>Mike M <[email protected]> wrote:
>>>I suspect he is being impacted by local rules.
>>
>>There was hardly anything in the municipal code that modified in any way
>>the National code.
>>
>>There was an addition that _any_ new (addition or replacement) panel had
>>to be inspected by the city, and something else equally earth-shaking. :)
>>
>>> I have used main
>>>breaker panels as sub panels when they are located a long ways from
>>>the main. I don't usually as cost of a 3 phase 208 volt 200 amp
>>>breaker adds quite an expense. Also since we usually have to protect
>>>according to available fault current fuses get a lot more practicle.
>>>I don't think NEC prohibits it. Feeders have to be protected where
>>>they are powered from unless using the tap rules.
>>
>>Yup. And there is apparently a requirement that _if_ there is a breaker
>>at the 'downstream' End of the feeder, it must be smaller than the one at
>>the 'powered from' end. which meant if I wanted to use a 100A 2-pole
>>in the in-unit panel, I had to have 'something bigger' at the feed end.
>>But, the building was built (1960s) using "Federal" breakers/panels, etc.
>>finding 'standard' replacements is an exercise in futility -- let alone
>>trying to find, say, a 125A one. the other option was to put something
>>'a little smaller' than 100A in the in-unit panel. It's amazing how scarce
>>'residential style' breakers are with ratings above 60A, and below 100A.
>>and how _expensive_ something like a 95A breaker of that ilk is.
>>
>Where I am we have NEC, state, and then local rules, not to mention
>sometimes building code or fire marshalls. Arguing with inspectors is
>a little like wallowing in the mud with pigs. Eventually you figure
>out they like it. LOL, and usually they can cite the code section.
>Mike
Ah well, I rarely argue with inspectors. Except when they're out-and-out
wrong, and I can prove it, that is. At another place, I crossed swords
with a City of Chicago electrical inspector -- over the City of Chicago
Electrical code. (The Chicago Code is _not_ based on the NEC, in fact it
predates it. It is much stricter than the NEC about some things, and more
lax about others. It is also written such that it is _very_ difficult to
figure out exactly what is, or is -not-, allowed in any given situation.
Methinks that this is deliberate, to enhance inspector revenues.)
Anyway, this inspector didn't like the way something had been done.
And cited the code section that it was in violation of. And I cited
the section that said _his_ section "didn't apply" if conditions X, Y and Z
were met, and that =this= installation have conditions X, Y, and Z.
He countered with a section that said condition Y had this other requirement
under "these" circumstances, and that we did fall under that. Whereupon
I pointed out that section thus-and-such said his section applied only
when condition W existed, which did not exist here. This went on for
a while, but eventually he "went away mad" -- *without* writing a violation,
*or* getting a bribe. He was _not_ a happy camper. :)
The next week the fire inspectors came calling. *sigh*
They were thorough, but didn't find anything that they could write a
violation for, either.
Unquestionably Confused <[email protected]> writes:
>brianlanning, or somebody so disguised, wrote the following at or about
>4/19/2006 11:38 AM:
>> >That is OK if you have less than 6 breakers in the sub.
>>> Should have said 6 or less
>>
>> How does the number of breakers in the subpanel matter?
>Probably just to give you a margin of "safety" so you're not continually
>popping the main breaker.
>60 Main and 6 or less 15a breakers. How likely is it that you'll have a
>10a+ load on six of them at the same time? Low, I'd say.
...but the 60A feed would be 240V (two legs of 120V), so it has the
capacity of handling 120A of 120V IF it is balanced between the two
legs....
>60A Main and, say, 12 breakers (mixed bag of 15A and 20A) much more
>likely to pop the main.
...not if each breaker is running at 10A and they are balanced between
the two 120V feeds. Once you get beyond that (up to the 15 or 20A values
on the breakers...) it's time to stand back.
>Not a safety issue, per se, more like a "this standard is engineered for
>the dumbest person." Think "I still have breakers and open outlets.
>How can I possibly overload this panel?"
Make 'em all 30A breakers 'cause they keep popping the 15A ones, and
see if you can get everything running and pop the main breaker before one
of the circuits burns down the house. :-)
>The financial corollary would be, "I can't be overdrawn! I still have
>checks in my checkbook!"<g>
...or "what do you mean the check bounced? There was room for all those
zeroes on the line for the amount!"
On 19 Apr 2006 13:29:47 -0700, [email protected] wrote:
> stormy2084 wrote:
> You're right, I should go with the bigger stuff. Is wire this large
> available at the "usual" places?
If you want copper, go to an electrical supply house for that. The local BORG
have sizes for this purpose, but in aluminum.
--
Art
Robert Bonomi wrote:
> "Cite please". It was established in another sub-thread that that
6-breaker
> max w/o a main cut-off applied to a 'service entrance' panel only. They
> even quoted the relevant NEC section. Now, the question is, can you back
> up -your- claim.`
>
> Note: the person posting the NEC section showing 'service entrance' only
> was someone who had made the same assentation you did, and was admitting
> he had been wrong.
No longer have access to a current code book.
My comment was based on being bloodied from having to work with local
inspectors and contractors as a distribution equipment supplier for
about 15 years.
Your description of your experience is certainly strange.
Just curious, was the main C/B visible from the distribution pnl in
question?
Lew
[email protected] writes:
>Greetings All!
>
>I am in the process of wiring up a shed in the backyard for use as a
>workshop. I have a new SquareD load center panel (QO8-16L100S) that I
>want to use but need some clarification.
> 1. This particular panel only has one grounding/neutral bar, but I was
>under the impression the ground and neutral must be separated in a
>subpanel installed in a stand alone structure. Should I just buy a
>ground bar and install it in the panel and connect it to a new
>grounding rod?
First, remove the bonding screw that bonds the grounded (neutral)
busbar to the enclosure. Second, purchase an accessory busbar and
fasten it to the enclosure as the grounding busbar. Third, bond the
grounding busbar in the subpanel to the grounding busbar in the
service entrance with the appropriate gauge green/bare conductor. You'll
also want to bond the grounded busbar in the subpanel to the grounded
busbar in the service entrance panel with suitably sized white conductor.
> 2. The panel is rated for 100A, but I was hoping to use a 60A-75A
>breaker in the main box to feed this subpanel. Is this a problem? The
>subpanel does not have a main breaker in it.
Not a problem.
> 3. The run from the main panel to the sub will only be about 15 ft.
>total. What size wire do you suggest I run?
If you use a 60A breaker, #6 should be sufficient at that length. Check
the NEC tables for definitive value based upon your conductor temperature
rating.
Are you using conduit and a thermoplastic insulated 90 degree-rated conductor
such as THHN or #6/3 w/g jacketed (which IIRC are 60 degree-rated conductors)?
scott
I bought 01 at Home Depot when replacing my main panel some years ago. I
suspect they have everything in between.
<[email protected]> wrote in message
news:[email protected]...
> stormy2084 wrote:
>> No - you should run 4 - two hots, a neutral and a ground.
>>
>> Because the cost difference isn't much, I'd recommend you go with #4 in
>> case you ever want to upgrade from the 60A to 100A. Also, be sure to
>> use large enough conduit (probably 2") so that you don't overfill.
>> Lots of other good responses here.
>
>
> You're right, I should go with the bigger stuff. Is wire this large
> available at the "usual" places?
>
>
>>
>> Lastly, do talk to your electrical inspector - not only is it the law
>> (almost everywhere) but it means you'll have a safe install and you
>> won't be on the line if your house burns down and it is traced back to
>> your work! Our local inspector is very helpful and is happy to help
>> DIY'ers.
>
>
> How do you normally contact the local inspector?
>
Somebody wrote:
>NEC requires a main for more than 6 breakers.
TRUE.
Known in some circles as the "6 hand" rule.
Regardless of whether a panel is a "sub" or a "main", you must be able
to disconnect ALL power distributed by that panel in a maximum of 6
motions of the hand.
I seen some very clever schemes used by some contractors in an attempt
to avoid a main C/B, but most don't get approved.
Lew
In article <[email protected]>, [email protected] wrote:
>Greetings All!
>
>I am in the process of wiring up a shed in the backyard for use as a
>workshop. I have a new SquareD load center panel (QO8-16L100S) that I
>want to use but need some clarification.
> 1. This particular panel only has one grounding/neutral bar, but I was
>under the impression the ground and neutral must be separated in a
>subpanel installed in a stand alone structure. Should I just buy a
>ground bar and install it in the panel and connect it to a new
>grounding rod?
Yes.
> 2. The panel is rated for 100A, but I was hoping to use a 60A-75A
>breaker in the main box to feed this subpanel. Is this a problem? The
>subpanel does not have a main breaker in it.
No. The 100A rating is a maximum. Nothing wrong with using equipment at less
than its rated capacity.
> 3. The run from the main panel to the sub will only be about 15 ft.
>total. What size wire do you suggest I run?
Depends on what breaker you use in the main panel, the type of wire, and how
it's installed. For THHN wires in conduit, you can go up to 75A on 6ga copper
wire.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
[email protected] wrote:
> I have a new SquareD load center panel (QO8-16L100S) that I
> want to use but need some clarification.
> 1. This particular panel only has one grounding/neutral bar, but I was
> under the impression the ground and neutral must be separated in a
> subpanel installed in a stand alone structure.
Buy a separate ground bar kit from a SQ D distributor and install it.
> 2. The panel is rated for 100A, but I was hoping to use a 60A-75A
> breaker in the main box to feed this subpanel. Is this a problem?
No. Just install a 2P-60 as a main C/B the in the sub panel.
> 3. The run from the main panel to the sub will only be about 15 ft.
> total. What size wire do you suggest I run?
Bigger is better.
I'd run #2 but #4 will do the job.
Lew
On Wed, 19 Apr 2006 21:18:15 GMT, Doug Miller wrote:
> >NEC requires a main for more than 6 breakers.
> >
> Cite, please? I thought that was for service entrances, not subpanels.
Hmmm. From my copy of the NEC 2002 Handbook:
230.71(A) "The service disconnecting means for each service permitted by
230.2, or for each set of service-entrance conductors permitted by 230.40,
Exception Nos. 1, 3, 4, or 5, shall consist of not more than six switches or
sets of circuit breakers ... "
408.16(A) "Each lighting and applicance branch-circuit panelboard
shall be individually protected on the supply side by not more than two main
circuit breakers or two sets of fuses having a combined rating not greater
than that of the panelboard."
"Exception No. 1: Individual protection for a lighting and appliance
panelboard shall not be required if the panelboard feeder has overcurrent
protection not greater than the rating of the panelboard."
Seems you're correct, Doug.
--
Art
[email protected] writes:
>Thank you for the detailed reply, Scott.
>
>Scott Lurndal wrote:
>> [email protected] writes:
>> >Greetings All!
>> >
>> >I am in the process of wiring up a shed in the backyard for use as a
>> >workshop. I have a new SquareD load center panel (QO8-16L100S) that I
>> >want to use but need some clarification.
>> > 1. This particular panel only has one grounding/neutral bar, but I was
>> >under the impression the ground and neutral must be separated in a
>> >subpanel installed in a stand alone structure. Should I just buy a
>> >ground bar and install it in the panel and connect it to a new
>> >grounding rod?
>>
>> First, remove the bonding screw that bonds the grounded (neutral)
>> busbar to the enclosure. Second, purchase an accessory busbar and
>> fasten it to the enclosure as the grounding busbar. Third, bond the
>> grounding busbar in the subpanel to the grounding busbar in the
>> service entrance with the appropriate gauge green/bare conductor. You'll
>> also want to bond the grounded busbar in the subpanel to the grounded
>> busbar in the service entrance panel with suitably sized white conductor.
>
>
>I should also use the bonding screw for the grounding busbar, right?
The screw that fastens the grounding busbar to the subpanel enclosure
serves as a bonding screw. Discard the bonding screw you remove from
the grounded busbar in the subpanel.
>
>
><snip>
>> > 3. The run from the main panel to the sub will only be about 15 ft.
>> >total. What size wire do you suggest I run?
>>
>> If you use a 60A breaker, #6 should be sufficient at that length. Check
>> the NEC tables for definitive value based upon your conductor temperature
>> rating.
>>
>> Are you using conduit and a thermoplastic insulated 90 degree-rated conductor
>> such as THHN or #6/3 w/g jacketed (which IIRC are 60 degree-rated conductors)?
>
>
>I was planning on burying with PVC type conduit and running #6/3
>w/g...assuming I can find that wire. Sounds good?
If you're burying the conduit, there is really no good reason to use
jacketed cable rather than individual conductors. Run four THHN or THW
conductors:
- #6 or #4 BLACK (current carrying conductor #1)
- #6 or #4 RED (current carrying conductor #2)
- #6 or #4 WHITE (grounded conductor, aka neutral)
- #8 or #6 GREEN (grounding conductor)
RED and BLACK are simply convention, you can use any color other
than white, green or green with yellow stripes for the current
carrying conductors. The RED and BLACK conductors must, of course,
be connected to different poles in the service entrance via a two-pole
breaker.
Watch your conduit fill percentage. 2" should be more than sufficient
as only two of the four conductors in the conduit carry current.
scott
I think we are interested in the STANDARDS here. From that one can determine
if he might get away with a higher gauge number on the wire or six 40AMP
breakers in the sub-panel knowing how far he is straying from what the EE's
recommend and building inspectors demand.
I ran #8 24' or more from my panel to my stove/oven as I recall so #6
sounded a bit conservative from my perspective.
But I always check the code requirements before installing or replacing
electric runs or panels and try to follow the standards or better during
installation.
Experience taught me that it is cheaper to do it "bullet proof" during the
installation than to retrofit subsequently.
Having said all that, he standards allow for quite a lot. But, then, the
house across the street burned down after some faulty electrical work by a
licensed electrician.
Telling the Fireman you figured you could get away with a cheaper breaker
box is not the conversation I want to have.
"brianlanning" <[email protected]> wrote in message
news:[email protected]...
> >That is OK if you have less than 6 breakers in the sub.
>>Should have said 6 or less
>
> How does the number of breakers in the subpanel matter?
>
> brian
>
On Sun, 23 Apr 2006 01:49:11 GMT, [email protected] (Doug Miller)
wrote:
>>I'm not sure I understand your explanation; however, the "6 hand rule"
>>applies if you are going to comply with NEC.
>
>For a service entrance, yes. If you maintain that the rule applies to
>subpanels as well, please cite the relevant article and section of the Code.
>
Also when you are serving a second building on the same service.
225.33
stormy2084 <[email protected]> wrote:
> No - you should run 4 - two hots, a neutral and a ground.
I think there is a choice here. He can run 4 wires as you say, keeping
ground and neutral separate in the subpanel, or he can run 3 wires
and put a grounding rod in at the outbuilding with a bonded ground
bus in the subpanel. I don't remember if there is some minimum
distance between buildings for that.
As others have suggested, I'd talk to the local inspector to see
what he/she expects. My local inspectors are generally very helpful
if you talk to them in advance.
Bill Ranck
Blacksburg, Va.
I suspect he is being impacted by local rules. I have used main
breaker panels as sub panels when they are located a long ways from
the main. I don't usually as cost of a 3 phase 208 volt 200 amp
breaker adds quite an expense. Also since we usually have to protect
according to available fault current fuses get a lot more practicle.
I don't think NEC prohibits it. Feeders have to be protected where
they are powered from unless using the tap rules.
Mike M
On Sat, 22 Apr 2006 22:10:41 GMT, Lew Hodgett
<[email protected]> wrote:
>Robert Bonomi wrote:
>
> > "Cite please". It was established in another sub-thread that that
>6-breaker
> > max w/o a main cut-off applied to a 'service entrance' panel only. They
> > even quoted the relevant NEC section. Now, the question is, can you back
> > up -your- claim.`
> >
> > Note: the person posting the NEC section showing 'service entrance' only
> > was someone who had made the same assentation you did, and was admitting
> > he had been wrong.
>
>
>No longer have access to a current code book.
>
>My comment was based on being bloodied from having to work with local
>inspectors and contractors as a distribution equipment supplier for
>about 15 years.
>
>Your description of your experience is certainly strange.
>
>Just curious, was the main C/B visible from the distribution pnl in
>question?
>
>Lew
On Wed, 19 Apr 2006 12:32:05 -0400, [email protected] wrote:
>> 2. The panel is rated for 100A, but I was hoping to use a 60A-75A
>>breaker in the main box to feed this subpanel. Is this a problem? The
>>subpanel does not have a main breaker in it.
>That is OK if you have less than 6 breakers in the sub.
>
Should have said 6 or less
On Sun, 23 Apr 2006 16:19:53 -0000, [email protected]
(Robert Bonomi) wrote:
>In article <[email protected]>,
>Mike M <[email protected]> wrote:
>>I suspect he is being impacted by local rules.
>
>There was hardly anything in the municipal code that modified in any way
>the National code.
>
>There was an addition that _any_ new (addition or replacement) panel had
>to be inspected by the city, and something else equally earth-shaking. :)
>
>> I have used main
>>breaker panels as sub panels when they are located a long ways from
>>the main. I don't usually as cost of a 3 phase 208 volt 200 amp
>>breaker adds quite an expense. Also since we usually have to protect
>>according to available fault current fuses get a lot more practicle.
>>I don't think NEC prohibits it. Feeders have to be protected where
>>they are powered from unless using the tap rules.
>
>Yup. And there is apparently a requirement that _if_ there is a breaker
>at the 'downstream' End of the feeder, it must be smaller than the one at
>the 'powered from' end. which meant if I wanted to use a 100A 2-pole
>in the in-unit panel, I had to have 'something bigger' at the feed end.
>But, the building was built (1960s) using "Federal" breakers/panels, etc.
>finding 'standard' replacements is an exercise in futility -- let alone
>trying to find, say, a 125A one. the other option was to put something
>'a little smaller' than 100A in the in-unit panel. It's amazing how scarce
>'residential style' breakers are with ratings above 60A, and below 100A.
>and how _expensive_ something like a 95A breaker of that ilk is.
>
Where I am we have NEC, state, and then local rules, not to mention
sometimes building code or fire marshalls. Arguing with inspectors is
a little like wallowing in the mud with pigs. Eventually you figure
out they like it. LOL, and usually they can cite the code section.
Mike
On 19 Apr 2006 08:44:42 -0700, [email protected] wrote:
> 1. This particular panel only has one grounding/neutral bar, but I was
>under the impression the ground and neutral must be separated in a
>subpanel installed in a stand alone structure. Should I just buy a
>ground bar and install it in the panel and connect it to a new
>grounding rod?
Yes and do not install the jumper/green screw that would bond the
neutral bar. Run a 4 wire feeder.
> 2. The panel is rated for 100A, but I was hoping to use a 60A-75A
>breaker in the main box to feed this subpanel. Is this a problem? The
>subpanel does not have a main breaker in it.
That is OK if you have less than 6 breakers in the sub.
> 3. The run from the main panel to the sub will only be about 15 ft.
>total. What size wire do you suggest I run?
4 ga copper is a good choice. That gets you up to 85a
The ground wire can be #8 copper up to 100a
In article <[email protected]>, Lew Hodgett <[email protected]> wrote:
>I'm not sure I understand your explanation; however, the "6 hand rule"
>applies if you are going to comply with NEC.
For a service entrance, yes. If you maintain that the rule applies to
subpanels as well, please cite the relevant article and section of the Code.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
In article <[email protected]>, [email protected] wrote:
>On 19 Apr 2006 09:38:44 -0700, brianlanning wrote:
>> >That is OK if you have less than 6 breakers in the sub.
>> >Should have said 6 or less
>>
>> How does the number of breakers in the subpanel matter?
>
>NEC requires a main for more than 6 breakers.
>
Cite, please? I thought that was for service entrances, not subpanels.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
Mike M wrote:
>Where I am we have NEC, state, and then local rules, not to mention
>sometimes building code or fire marshalls. Arguing with inspectors is
>a little like wallowing in the mud with pigs. Eventually you figure
>out they like it. LOL, and usually they can cite the code section.
>Mike
I agree, but the *code* they cite isn't always in the books...
In my town the inspector was busting my gonads about building a simple
shed, and he was using some interesting *interpretations* of state code.
So when I copied the code from the book and then called the state and
made a recording of the official telling me the inspector cannot
supersede state code on that matter (and played it for him), he
relented. But I'm wary of what he will do upon final inspection of the
site - these guys tend to have long (and mean) memories.
In another town when we had an inspection of the new breaker panel
replacement in my mother's house, the town electrical inspector insisted
we pay for a plumbing permit and refused to sign off on the electrical
inspection. He was looking at a short piece of PVC that was used as a
drain from the furnace's humidifier down to the sump (this was on the
other side of the basement, no connection to the electrical work). That
installation was from more than 20 years ago, and since mom died we
couldn't ask her for the copy of the paper work from the contractor for
the installation, so the inspector said we could not have a C.O. for the
house.
These guys are just plain evil.
Since my profession is a "catastrophe" insurance adjuster, may I suggest if
you live in an area that doesn't have a-holes for inspectors, get a permit &
have it inspected. Should your workshop burn due to an electrical problem
some of the insurance companies will try to use "your" contributory
negligence to gain a little wiggle room. Also take pictures of your work and
do a diagram with materials used. Keep receipts. It's not often, but some
adjusters will push on you to accept less in fear that a battle will yield
nothing . . . just my two cents . . . Also always keep your agent up to
date on any new out buildings and their content in $$$$$. . . . Most home
owner policies only give you 10% on all out buildings combined. That's 10%
of your total home owners value. $300,00.00 home, you have $30,000.00
coverage on out buildings . . . If your shop is attached to the home, ie . .
garage, that does not apply . . . Also, if you sell anything out of your
home shop, make sure you incorporate the work "STUDIO" as in art into the
business name . . . . Home being used for business purposes nulls your
coverage in most cases . . . .
"Lew Hodgett" <[email protected]> wrote in message
news:[email protected]...
> [email protected] wrote:
>
> > I have a new SquareD load center panel (QO8-16L100S) that I
> > want to use but need some clarification.
> > 1. This particular panel only has one grounding/neutral bar, but I was
> > under the impression the ground and neutral must be separated in a
> > subpanel installed in a stand alone structure.
>
> Buy a separate ground bar kit from a SQ D distributor and install it.
>
> > 2. The panel is rated for 100A, but I was hoping to use a 60A-75A
> > breaker in the main box to feed this subpanel. Is this a problem?
>
> No. Just install a 2P-60 as a main C/B the in the sub panel.
>
> > 3. The run from the main panel to the sub will only be about 15 ft.
> > total. What size wire do you suggest I run?
>
> Bigger is better.
>
> I'd run #2 but #4 will do the job.
>
> Lew
>
brianlanning, or somebody so disguised, wrote the following at or about
4/19/2006 11:38 AM:
> >That is OK if you have less than 6 breakers in the sub.
>> Should have said 6 or less
>
> How does the number of breakers in the subpanel matter?
Probably just to give you a margin of "safety" so you're not continually
popping the main breaker.
60 Main and 6 or less 15a breakers. How likely is it that you'll have a
10a+ load on six of them at the same time? Low, I'd say.
60A Main and, say, 12 breakers (mixed bag of 15A and 20A) much more
likely to pop the main.
Not a safety issue, per se, more like a "this standard is engineered for
the dumbest person." Think "I still have breakers and open outlets.
How can I possibly overload this panel?"
The financial corollary would be, "I can't be overdrawn! I still have
checks in my checkbook!"<g>
[email protected] writes:
> How do you normally contact the local inspector?
Your local city/town hall (i.e. town clerk) would know who the
inspector is.