service size

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skoal7839 said:
would a 100amp service be big enough for a 20kw furnace this would be the only load hooked up to it
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I'm sure you'll get better comments than mine, (Im a has been) but assuming single phase 240 looks like 83, PLUS the blower motor, maybe 1/2 or 3/4hp I'd say your over, or hanging on a thread and a prayer. Besides cracking open the code book, look for the data plate, most HVAC equip has a min circuit amps posted
 
Mule, Its for fixed electric space heating: 424.3(B) ?Fixed electric space heating equipment shall be considered continuous load.?

And 210.19(A)(1) with 210.20(A), for ?continuous loads? conductors and overcurrent protection is sized at 125% of the load.
 
skoal7839 said:
would a 100amp service be big enough for a 20kw furnace this would be the only load hooked up to it
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Let's assume you mean feeder not service. In either case, it won't fly, however many 20 kw furnace are only 19.2 kw. It may fly as a feeder. I would check the nameplate since you must also consider the fan in the calculation.
 
tryinghard said:
Mule, Its for fixed electric space heating: 424.3(B) ?Fixed electric space heating equipment shall be considered continuous load.?

And 210.19(A)(1) with 210.20(A), for ?continuous loads? conductors and overcurrent protection is sized at 125% of the load.
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However, when one goes to (2002) 424.22(D), it appears to allow sizing the conductors at 100% of nameplate. (???). I've never understood why the difference in wording between the two articles.

cf
 
Cold Fusion said:
However, when one goes to (2002) 424.22(D), it appears to allow sizing the conductors at 100% of nameplate. (???). I've never understood why the difference in wording between the two articles.

cf
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This is in 05 as well but it?s for "supplemental overcurrent protection", additional to the required.

Notice definition of Supplementary Overcurrent Protective Device: ??This limited protection is in addition to the protection provided in the required branch circuit by the branch circuit overcurrent protective device.?
 
so if I have a furnace with a mca of 51 and a mop of 60 than I have to take 51 times a 125% which would require a run of 4/2g instead of 6/2g
 
eds said:
so if I have a furnace with a mca of 51 and a mop of 60 than I have to take 51 times a 125% which would require a run of 4/2g instead of 6/2g
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No- I don't think so -- the 125% is in there already.
 
acording to post #12 and the code sections mentioned do we know that this is already taken into account
 
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