# Storage warehouse service load calculation



## ABOLT1985 (Feb 24, 2012)

I have a load calculation question on a storage warehouse that I will be putting a new service on it due to the owners adding 4- a/c units with each unit pulling 60amps. So a total of 240amps that I will be adding. It already has a 200 amp service on it now.I would like some help with the calculations and where it would be in the code book. I figured out the lighting calculations a little confused on the receptacle calculations. Also the a/c units will be calculated at 125% I think due to the continuous duty? And is the wire sized off of the 65 deg or 75 deg. thanks for the help a little new to this stuff mainly do residential stuff but would like to do more commercial.


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## ABOLT1985 (Feb 24, 2012)

ABOLT1985 said:


> I have a load calculation question on a storage warehouse that I will be putting a new service on it due to the owners adding 4- a/c units with each unit pulling 60amps. So a total of 240amps that I will be adding. It already has a 200 amp service on it now.I would like some help with the calculations and where it would be in the code book. I figured out the lighting calculations a little confused on the receptacle calculations. Also the a/c units will be calculated at 125% I think due to the continuous duty? And is the wire sized off of the 65 deg or 75 deg. thanks for the help a little new to this stuff mainly do residential stuff but would like to do more commercial.


65 views no help come on people


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## CallMeAndrew (Jul 18, 2013)

You should check section 8 in the cec about demands. also, you would use the degrees of the breaker.. so 75? hope that helps


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## FastFokker (Sep 18, 2012)

CallMeAndrew said:


> You should check section 8 in the cec about demands. also, you would use the degrees of the breaker.. so 75? hope that helps


What good is the CEC going to do him?


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## CallMeAndrew (Jul 18, 2013)

FastFokker said:


> What good is the CEC going to do him?


no one was helping him, thought id be the nice guy..


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## varmit (Apr 19, 2009)

I will make a stab at this from the info provided.

I would agree that the A/C load should be figured as continuous. ( I lived in Oklahoma for a few years in the 80s. I know how hot it can be there.) The "Code minimum" for general lighting is 1/4 va/ft. The actual true illumination load can vary dramatically depending on the level of light desired. The calculated receptacle load would depend on the number of receptacles installed based on 180 va per outlet.

The wire size would be based on 75C, as most all terminations are rated for 75C.

IF NO OTHER LOADS ARE BEING ADDED AND IF THE EXISTING SERVICE IS NOT OVERLOADED, a 400 amp service COULD POSSIBLY be sufficient. If so, a 400 amp service would be close to it's capacity. Depending on all of the load factors, a 500 or 600 amp service could be required to allow for future capacity. A good, free resource would be to obtain the past electrical use from the utility company. OG&E? This would give some real world basis for sizing the service increase.

Do the A/C units actually draw 60 amps each, or is this the "minimum circuit required"? There is a big difference. Typically a 60 amp circuit will have a FLA of closer to 40 to 48 amps.

There is a considerable price difference between materials for a 400 vs 600 amp service, but you need to install to allow for at least some limited future loads. This amount will vary depending on your local AHJ.


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## varmit (Apr 19, 2009)

Ok, here are some theoretical numbers based on 50,000 square feet and a 208, 3 phase service:

50,000 SF @ .25 va = 35 amp for lighting ( as noted in previous post , this number can vary based on actual lighting level.

50 each 120 volt outlets= 25 amp

4 each A/C units @48 amps = 192 amp

1 water heater 4500 watt = 22 amp

Other loads:
Office HVAC
Server/network (?) 
Exhaust fans (?)
 Any special equipment (?)
Dock leveler hydraulic pump(s)
Trash compactor (?)
Outside lighting (?)

What ever the final calculated load may be, remember that no standard fuses or breakers will hold when operated at 100% of their rating continuously. Normally 80% is the practical limit.


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## ABOLT1985 (Feb 24, 2012)

thanks varmit the warehouse is 32,000 sq' the max fuse is 60 on them a/c units i was told that what i have to allow for because of the AHJ.


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