kilowatt permit

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Old 10-26-09, 05:08 PM
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kilowatt permit

Im filling out a electric permit. they want the size and qty of each. my furnace is drawing 8 amps and is 115 volt ,15 amp breaker I cant remember what a electrain told me in the past. my condenser is 220 volts min breaker 25 max 35
 
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Old 10-26-09, 05:41 PM
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What is this permit supposed to permit? Why isn't the whole house in on this rating?

If you are required to choose the higher number based on starting current, lockup, or whatever, I figure it to be about 9 Kw. Otherwise the running current be under 6 Kw.

Why don't you call them if you need to be accurate, and ask them what figures off their rating plates that they want you to go by. And if there is any jailtime if a layperson, like yourself, puts down some slightly wrong number(like you are off by double ) when this is not being done by a certified electrician.
 

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Old 10-26-09, 05:47 PM
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Sounds to me like you have one 15 amp, 120 volt circuit, and one 30 amp, 240 volt circuit.
 
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Old 10-27-09, 03:38 AM
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I am the contractor hvac 24 years, I do know wiring and the proper way of sizing, installing,ect.many classes on electric. I am pulling a permit with the Twp. to replace a furnace and air conditioner.
plumbing & fire & chimneyl by me. homeowner will be pulling electric on his own to re wire furnace and condenser (electrical engineer)he ask that i fill in the basic info on the permit and he will sign off on it. I will be making sure he puts in the proper way per code.
yeas its been a while since ohms law.
side note: I have properly install sub panels,branch curcits,wired many appliances,built a fm radio,transformer,1 yr course in computer repairs.

15/115= 7.6
30/220=7.3 ?
 
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Old 10-27-09, 08:57 AM
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The furnace is drawing 8A at 120V. That's 8A * 120V = 960 Watts. Divide by 1000 to get 0.96 kilowatts.

AC is drawing no more than 25A at 240V: 25A * 240V = 6000W or 6kW maximum running current.

If you want to get a more accurate number for the AC, look on the electrical nameplate on the unit itself for the "FLA" or "full load amps" and use that to calculate using the same formula as above.

If you used the LRA or "locked rotor amps" that would tell you how much power the unit pulls for the brief period during motor startup. It's usually several times higher than FLA. For your permit they only care about the FLA, I just added this bit for your curiosity.

For code, the AC circuit should be run with 10-2g cable and a 30A breaker; the furnace with 14-2g cable and a 15A breaker.
 
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Old 10-27-09, 09:34 AM
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Possibly the reason that when an electrical permit is submited for approval ,the permit must present an accurate list of the connected load on the Service Condutors in order to avoid overloading the Service with an additional load that is being installed subject to permit-approval.

For example , if you were installing a new HVAC system in a premises with a 60 amp Service with 220 loads that included a range , water-heater, and dryer, the additional compressor motor load could possibly result in a total load that would result in the existing 60 amp Service Condutors being inadequate.

This permit requirement may not seem relevant when adding a small load to a 200 amp Service, but it's probably SOP with all electrical permits submitted to the municipality with Code-enforcement authority.
 
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Old 10-27-09, 01:18 PM
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Originally Posted by ibpooks View Post
The furnace is drawing 8A at 120V. That's 8A * 120V = 960 Watts. Divide by 1000 to get 0.96 kilowatts.

AC is drawing no more than 25A at 240V: 25A * 240V = 6000W or 6kW maximum running current.

If you want to get a more accurate number for the AC, look on the electrical nameplate on the unit itself for the "FLA" or "full load amps" and use that to calculate using the same formula as above.

If you used the LRA or "locked rotor amps" that would tell you how much power the unit pulls for the brief period during motor startup. It's usually several times higher than FLA. For your permit they only care about the FLA, I just added this bit for your curiosity.

For code, the AC circuit should be run with 10-2g cable and a 30A breaker; the furnace with 14-2g cable and a 15A breaker.
thanks for the formula .
 
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