Flameproof suit on.
Laguna says 30 Amp breaker on 220 Volt service is needed for the
LT16HD (4.5 HP Baldor motor).
My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
Is the start-up draw 30% higher than the run draw?
I have 220V 20A service and 10-3 wiring installed over about a 20'
span and wonder if I need to go up to a 30 Amp breaker.
I could just plug it in, crank it up, and see if the breaker pops :-).
Flameproof suit off.
Regards.
Tom
"DJ Delorie" <[email protected]> wrote in message
news:[email protected]...
>
> "Jim" <[email protected]> writes:
>> The Delta manual shows that a 5 HP motor can draw up to 28 amperes.
>
> The motor in my central A/C unit draws 30 amps once it's running, but
> needs 123 amps (at 240V!) for a few seconds to get started.
>
> So yeah, go with the manufacter's recommendation, not pure math.
You are so right. When I mentioned 28 amperes, I intended that to mean the
current that flows after the motor gets started.
Jim
Tom B wrote:
> Laguna says 30 Amp breaker on 220 Volt service is needed for the
> LT16HD (4.5 HP Baldor motor).
Sounds reasonable.
> My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
That would be wrong. I'd guess closer to 20A after standard motor
efficiency and power factor. My 3HP motor is about 13A.
> Is the start-up draw 30% higher than the run draw?
Easily. Sometimes much more. On dedicated motor circuits you can
sometimes use breakers up to 4x the "normal" breaker size to cover
startup draw.
> I have 220V 20A service and 10-3 wiring installed over about a 20'
> span and wonder if I need to go up to a 30 Amp breaker.
Likely, yes.
> I could just plug it in, crank it up, and see if the breaker pops :-).
One option, certainly.
Chris
"Tom B" <[email protected]> wrote in message
news:[email protected]...
> On Fri, 04 May 2007 16:40:19 GMT, "Toller" <[email protected]> wrote:
>
>
>>
>>Better do a slower calc. Probably about 23a.
>>>
>
>
> Don't doubt you're right as I just used:
>
> E=IR or I=E/R
>
> W=I^2R or I*(E/R)*R
>
> therefore
> W=EI
>
> so 220V*20A = 4400 watts (avaialble)
>
> 1HP (electrical) = .746KW (source IEEE handbook circa 1968)
> 4.5HP= 4.5*746 = 3357 watts (required)
>
> Obviously I missed something like adjusting for efficiency.
>
> Don't have the saw yet so I can't read the plate on the motor.
>
> In any case, thanks for the input.
>
> Regards.
Those are calcs based on Ohm's law which is for DC. This AC. You have to
include Power Factor. There's also efficiency. Both will yield a higher
current than your calcs.
Bob
Leon:
Thanks. Good idea but our drier is in the house, 80' from the
gara-shop.
In any case, I put in a new breaker this evening, so all is well - no
damage, no sparks, got volts. TS runs fine on it and I'll use the same
outlet for the BS when it arrives. One at a time of course. Only one
of me so having both saws going at once makes zero sense. Dust
collector is on a separate 220 circuit.
Reagrds.
Tom
On Fri, 4 May 2007 16:49:53 -0500, "Leon"
<[email protected]> wrote:
>Tom, I tapped into the dryer wall outlet and attached an extra 220 volt
>outlet within a few inches of the dryer outlet. I used the more standard
>outlet plug set up so that I could run my Planer and Table Saw from that
>outlet also. I run a 30' 10-3 extension cord from the outlet to the tool.
>This way the dryer stays plugged in all the time and the "Kingdom" runs
>smoothly. ;~)
>
Thanks to all for the responses.
Net/net - why be pound foolish? Spend $3K on a saw, blades, base, etc
and not spend a few bucks and a few scary minutes (I hate doing 220 in
the breaker box, though I lived with it overseas for years) on a
circuit for it? Case of the dumbs.
Though I do like the idea of using the dryer (or stove) circuit -
HMMM.
No, last thing I need is to have to explain to SWMBO that my new high
$$ toy fouled up her kingdom's smooth operation. That could get really
expensive! New breaker it is.
Regards.
Tom
On Fri, 04 May 2007 09:31:07 -0500, Tom B
<[email protected]> wrote:
>Flameproof suit on.
>
>Laguna says 30 Amp breaker on 220 Volt service is needed for the
>LT16HD (4.5 HP Baldor motor).
>
>My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
>
>Is the start-up draw 30% higher than the run draw?
>
>I have 220V 20A service and 10-3 wiring installed over about a 20'
>span and wonder if I need to go up to a 30 Amp breaker.
>
>I could just plug it in, crank it up, and see if the breaker pops :-).
>
>Flameproof suit off.
>
>Regards.
>
>Tom
"Tom B" <[email protected]> wrote in message
news:[email protected]...
> Flameproof suit on.
>
> Laguna says 30 Amp breaker on 220 Volt service is needed for the
> LT16HD (4.5 HP Baldor motor).
>
> My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
>
> Is the start-up draw 30% higher than the run draw?
>
> I have 220V 20A service and 10-3 wiring installed over about a 20'
> span and wonder if I need to go up to a 30 Amp breaker.
>
> I could just plug it in, crank it up, and see if the breaker pops :-).
>
> Flameproof suit off.
>
> Regards.
>
> Tom
First of all, it won't hurt the wiring if the circuit breaker is too small.
Instead, you will eventually get tired of tripped breakers.
The Delta manual shows that a 5 HP motor can draw up to 28 amperes.
Frankly, I expect that Baldor knows more about the requirements of their
motors than any of us. Hence, I would follow their instructions.
Incidentally, my table saw has a 1 HP repulsion-induction motor which is
rated at 11 amperes. Despite this, I have tripped a 20 ampere circuit
breaker while I was ripping some wood.
Jim
"Tom B" <[email protected]> wrote in message
news:[email protected]...
> Thanks to all for the responses.
>
> Net/net - why be pound foolish? Spend $3K on a saw, blades, base, etc
> and not spend a few bucks and a few scary minutes (I hate doing 220 in
> the breaker box, though I lived with it overseas for years) on a
> circuit for it? Case of the dumbs.
>
> Though I do like the idea of using the dryer (or stove) circuit -
> HMMM.
>
> No, last thing I need is to have to explain to SWMBO that my new high
> $$ toy fouled up her kingdom's smooth operation. That could get really
> expensive! New breaker it is.
>
> Regards.
>
> Tom
Tom, I tapped into the dryer wall outlet and attached an extra 220 volt
outlet within a few inches of the dryer outlet. I used the more standard
outlet plug set up so that I could run my Planer and Table Saw from that
outlet also. I run a 30' 10-3 extension cord from the outlet to the tool.
This way the dryer stays plugged in all the time and the "Kingdom" runs
smoothly. ;~)
In article <[email protected]>, Tom B <[email protected]> wrote:
>Flameproof suit on.
>
>Laguna says 30 Amp breaker on 220 Volt service is needed for the
>LT16HD (4.5 HP Baldor motor).
>
>My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
That's assuming 100% efficiency, which you're not going to get. Figure
*at*least* 20A, probably more.
>
>Is the start-up draw 30% higher than the run draw?
No, it's even worse than that.
>
>I have 220V 20A service and 10-3 wiring installed over about a 20'
>span and wonder if I need to go up to a 30 Amp breaker.
The manufacturer recommends a 30A circuit.
10-3 wire will support a 30A circuit.
A 30A double pole breaker will cost about ten bucks, and take you fifteen
minutes, tops, to swap in.
Doesn't sound like a difficult decision to me.
>I could just plug it in, crank it up, and see if the breaker pops :-).
Yes, you could. Or you could spend the ten bucks and fifteen minutes, and
put in the correct breaker.
Your choice. :-)
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
"Tom B" <[email protected]> wrote in message
news:[email protected]...
> Flameproof suit on.
>
> Laguna says 30 Amp breaker on 220 Volt service is needed for the
> LT16HD (4.5 HP Baldor motor).
>
You think they are trying to scare off customers by demanding too large a
circuit? Seems like an odd sales strategy.
> My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
Better do a slower calc. Probably about 23a.
>
> Is the start-up draw 30% higher than the run draw?
>
No, about 200% higher.
> I have 220V 20A service and 10-3 wiring installed over about a 20'
> span and wonder if I need to go up to a 30 Amp breaker.
>
Sounds like a simple solution.
> I could just plug it in, crank it up, and see if the breaker pops :-).
>
Yeah, but since you know it will, why not do it properly?
> Flameproof suit off.
>
> Regards.
>
> Tom
On 04 May 2007 22:28:47 -0400, DJ Delorie <[email protected]> wrote:
>Note that putting a 30 amp breaker on wire that isn't rated for 30
>amps is, at least in most (if not all) US cities, illegal. Make sure
>the wire is able to carry the current, else it poses a fire hazard.
>(the breaker protects the wire, not your tool)
The original post indicated that the circuit was wired with 10-3. I
wonder why it didn't have a 30 amp breaker from the start. Else why
use 10 ga wire.
Tom B wrote:
> New breaker it is.
It's NBD, IF you approach it right.
Remove load center cover.
Pop out existing c'bkr with a rocking motion disconnecting c'bkr from
L/C bus bar.
Change out c'bkr with it in your hand and disconnected from L/C.
Pop c'bkr back in place with a rocking motion such that c'bkr contacts
contact bus bar last.
Replace L/C cover.
If the above scares you, stick flash light in mouth, shut off main
c'bkr in L/C, the do as above.
Lew
On Fri, 04 May 2007 16:40:19 GMT, "Toller" <[email protected]> wrote:
>
>Better do a slower calc. Probably about 23a.
>>
Don't doubt you're right as I just used:
E=IR or I=E/R
W=I^2R or I*(E/R)*R
therefore
W=EI
so 220V*20A = 4400 watts (avaialble)
1HP (electrical) = .746KW (source IEEE handbook circa 1968)
4.5HP= 4.5*746 = 3357 watts (required)
Obviously I missed something like adjusting for efficiency.
Don't have the saw yet so I can't read the plate on the motor.
In any case, thanks for the input.
Regards.
Lew:
Thanks. I'm a CS. I shut the mains down, checked voltage across the
bus bars, replaced 20 amp with a 30 amp, backed off and reset the
mains. All done, no sparks.
The work I do for a living is on the theorectical side of circuits
that couldn't draw an amp in a millenium without frying. But I can
wire a light switch!
Regards.
On Fri, 04 May 2007 21:52:15 GMT, Lew Hodgett
<[email protected]> wrote:
>Tom B wrote:
>
>> New breaker it is.
>
>It's NBD, IF you approach it right.
>
>Remove load center cover.
>
>Pop out existing c'bkr with a rocking motion disconnecting c'bkr from
>L/C bus bar.
>
>Change out c'bkr with it in your hand and disconnected from L/C.
>
>Pop c'bkr back in place with a rocking motion such that c'bkr contacts
>contact bus bar last.
>
>Replace L/C cover.
>
>If the above scares you, stick flash light in mouth, shut off main
>c'bkr in L/C, the do as above.
>
>Lew
"Tom B" <[email protected]> wrote in message
news:[email protected]...
> Flameproof suit on.
>
> Laguna says 30 Amp breaker on 220 Volt service is needed for the
> LT16HD (4.5 HP Baldor motor).
>
> My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
>
> Is the start-up draw 30% higher than the run draw?
I would imagine at least 30% more. That said, I have the same saw and run
it on my 30 amp Dryer Circuit at the same time that the dryer is running
with no sign of voltage drop. The saw starts the same whether the dryer is
running or not.
>
> I have 220V 20A service and 10-3 wiring installed over about a 20'
> span and wonder if I need to go up to a 30 Amp breaker.
If you get into resawing wider boards you may blow the breaker on a 20 amp.
On a side note, I can run my 22/44 drum sander that requires a 20 amp
circuit and my 1100 CFM Dust Collector on a 15 amp circuit but on wider
boards I will blow a breaker. Both running off of the 20 amp washer circuit
works great.
>
> I could just plug it in, crank it up, and see if the breaker pops :-).
I would be suprised if it blows on start up, it'll blow in the middle of a
resaw job. ;~)
Steve knight wrote:
> most power tools don't draw a huge amount of power starting up because
> the load is not a lot. now what a real power sucker going to my larger
> cyclone and that thing draws some real power getting going. far more
> then any other tool in my shop.
A high startup current of a motor is caused by the motor's windings
providing a direct short across the line. After the initial surge the
motor produces a counter voltage, known as a counter electro motive
force (EMF), as a result of the collapsing magnetic field around the
coils as the voltage cycles. This counter EMF acts as a resistance
limiting the current once it has been started.
--
Jack Novak
Buffalo, NY - USA
[email protected]
Tom B wrote:
> Flameproof suit on.
>
> Laguna says 30 Amp breaker on 220 Volt service is needed for the
> LT16HD (4.5 HP Baldor motor).
>
> My quick calc shows 4.5 HP on 220V is ~3375 Watts or about 15.3 Amp.
What does the spec. plate on the motor indicate?
>
> Is the start-up draw 30% higher than the run draw?
According to Leeson, "the starting current, usually 450 to 575% of rated
current,"
http://www.iprocessmart.com/leeson/leeson_singlephase_article.htm
>
> I have 220V 20A service and 10-3 wiring installed over about a 20'
> span and wonder if I need to go up to a 30 Amp breaker.
>
> I could just plug it in, crank it up, and see if the breaker pops :-).
>
Ayup.
--
Jack Novak
Buffalo, NY - USA
[email protected]
"Jim" <[email protected]> writes:
> The Delta manual shows that a 5 HP motor can draw up to 28 amperes.
The motor in my central A/C unit draws 30 amps once it's running, but
needs 123 amps (at 240V!) for a few seconds to get started.
So yeah, go with the manufacter's recommendation, not pure math.
Tom Veatch writes:
> The original post indicated that the circuit was wired with 10-3. I
> wonder why it didn't have a 30 amp breaker from the start. Else why
> use 10 ga wire.
I figured that, but just in case someone googled it and came in
halfway, I wanted that caveat to be there.
I've seen lots of recommendations here to use the next-size-bigger
wire just to avoid resistive losses, no surprises there.
And, it's possible to get 10 gauge wire that is *not* rated for 30
amps, depending on the insulation it's got. Remember, it's a fire
thing, not a capacity thing. Unlikely, but something to beware of.
Tom B <[email protected]> writes:
> Thanks. I'm a CS. I shut the mains down, checked voltage across the
> bus bars, replaced 20 amp with a 30 amp, backed off and reset the
> mains. All done, no sparks.
Note that putting a 30 amp breaker on wire that isn't rated for 30
amps is, at least in most (if not all) US cities, illegal. Make sure
the wire is able to carry the current, else it poses a fire hazard.
(the breaker protects the wire, not your tool)