AC unit question

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Ivan Young

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Simpsonville, South Carolina
Happy hump day to all pros on this site. I have a question about a AC unit installed in a four year old house that I am in the process of buying.
The house has a 3 ton unit, air handler in the attic, gas powered heat.
The specs on the name sticker is as follows : compressor-19.9 RLA. Fan motor 1/4hp 1.4 FLA. Minimum circuit amps 26.2 amps. Maximum fuse 40 amps. Maximum circuit breaker 40 amps.
From the panel to the unit is about 10 feet. The panel has a 40 amp breaker fed by #10 wires to a pull-out disconnect rated at 30 amps. #10 wires from the disconnect to the unit. The home inspector says everything is fine except for the disconnect which he says should be rated more than 30 amps. Home owner's inspector disagrees and says 30 amp is fine. Who is correct?
Also air handler is protected by 15 amp circuit.
Any help would be greatly appreciated.
 
IMO the 30 amp disconnect is fine. You could also change the OCPD to 30 amps instead of 40 amps then the argument disappears completely.
 
Thanks for your help Rob. I just have one final question. If the sale goes through, I would like to replace that disconnect with a better one. One with the on/off handle and the two fuses that looks like shot gun shells. Should I use 30 or 40 amp fuses? I remember the inspector saying the disconnect the disconnect should be rated at 60 amps.
 
Ivan Young said:
Thanks for your help Rob. I just have one final question. If the sale goes through, I would like to replace that disconnect with a better one. One with the on/off handle and the two fuses that looks like shot gun shells. Should I use 30 or 40 amp fuses? I remember the inspector saying the disconnect the disconnect should be rated at 60 amps.
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You do not need a fused disco, you are already protected by the breaker and motor overloads.
 
Using a 60A disco with 30A fuses fed by a 40A breaker is compliant. Using 40A fuses in a 30A disco is not afaik. Is the disco rated at 30A or does it have 30A fuses in it???

If you want a 60A fused disco, go for it. A Midwest or GE 60A fused AC disco is about $18 and the slow-blow motor rated 40 fuses are I think about 10 or so. A non-fused 60A disco is about $9.

http://www.homedepot.com/p/GE-60-Amp-240-Volt-Fused-AC-Disconnect-TF60RCP/100134720

http://www.homedepot.com/p/GE-60-Amp-240-Volt-Non-Fuse-Metallic-AC-Disconnect-TFN60RCP/100674085

$20 difference. If you ever get a new AC unit that requires smaller fuses, it may be cheaper to change those than the breaker in the panel. On the down side, fuses cost more and there is another point in the circuit that needs to be checked if there is a failure.

For some panels like old FPE Stab Lock, I would definitely use a fused disco rather than rely on those old 2p breakers to trip.
 
Thanks Rob and Jumper. I haven't the foggiest why the inspector wants a 60 amp disconnect. So I am guessing that if want to replace the disconnect I don't have to use a fused one, but if I do use a fused one the I can use a 40 amp rated one ?
 
Ivan Young said:
Thanks Rob and Jumper. I haven't the foggiest why the inspector wants a 60 amp disconnect. So I am guessing that if want to replace the disconnect I don't have to use a fused one, but if I do use a fused one the I can use a 40 amp rated one ?
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There are no 40A rated discos, only 30 and 60. Putting in a 30A breaker/fuses may cause motor trips as that OCPD is on the low end of what's allowed.
 
Ivan Young said:
In that case I guess my best option would be to use a unfused disco.
Thanks for all the help guys.
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Unless one of the components of the installation were damaged I wouldn't change anything since the installation is code complaint.
 
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