Incorrect Wire?

[nbhi]

Here are a couple of pic's from todays inspection.
There is a 40 amp double pole breaker, third on right, for the AC, that is wired using 12/2 romex? The wire for that size of breaker is to small correct? But the amps on the ac says, 23.6amp.

The second pic shows oxidation on the lead feeding the panel is this an issue that should be called out?

[ATTACH][/ATTACH]

[Jim Port]

AC loads do not use the same wire sizes as regular branch circuits. The breakers are sized for the starting current. The wire is sized for the run current. To verify proper wire sizes you need to look at the nameplate to check the minimum circuit size.

[nbhi]

Jim
The minimum is 23.6 amps

[gbeaumont]

Hi Gary,

I can't comment on the wire guage (but that ain't a 12/2) it many be a 12awg, but the real issue is that the compressor is I think an upgrade from the homes original one, and the new one requires less amps than the original, if that is the only disconnect for the AC then it is "over fused" however it may have an outside disconnect rated lower.

Regards

Gerry

[nbhi]

Gerry
It does have a pull fuse at the unit outside.

[gbeaumont]

Originally Posted by nbhi

Gerry
It does have a pull fuse at the unit outside.

What is that rated at??

Regards

Gerry

[nbhi]

30amps. Buy isn't that for when the unit is being serviced? That way the power can be disconnected at the unit. It doesn't trip?

[gbeaumont]

Originally Posted by nbhi

30amps. Buy isn't that for when the unit is being serviced? That way the power can be disconnected at the unit. It doesn't trip?

Gary, it's still a fuse isn't it??? that will blow at 30 amps, well before the breaker would trip wouldn't it??

Do you have a picture of the data plate you can post?

Gerry

[nbhi]

What about the first pic with the oxidation? Is this an issue that should be called out? Could that connection become a problem in the furture?

[nbhi]

Gerry
The wire being used for the AC is 12/2 awg. It is stamp on the outside of the wire. Wouldn't this wire be under sized for the breaker,40amp, even though the min. amps is 23.6 on the boiler plate?

[Mike Whitt]

Originally Posted by nbhi

Gerry

Originally Posted by nbhi

The wire being used for the AC is 12/2 awg. It is stamp on the outside of the wire. Wouldn't this wire be under sized for the breaker,40amp, even though the min. amps is 23.6 on the boiler plate?

When dealing with any motor load the breaker or fuse MUST be able to let the motor start.
The fuse or breaker is installed for the SOLE purpose of opening in the event that the hot wires get shorted to each other or to some part of the metal that encloses them.

The AC unit will have an integral overload device that is responsive to motor current. This integral over load will open in the event that the unit starts overheating and also protects the conductors that are installed to the unit.

[nbhi]

So Mike, The wire being smaller than the breaker, which is 40 amps double pole, is ok, since the amps on the boiler plate,ac, is 23.6amps?

[gbeaumont]

Originally Posted by nbhi

Gerry
The wire being used for the AC is 12/2 awg. It is stamp on the outside of the wire. Wouldn't this wire be under sized for the breaker,40amp, even though the min. amps is 23.6 on the boiler plate?

Gary, as others have said you really need the manufacturers installation instructions. A 12awg is rated for 25amps when starting a motor (a compressor is a motor) If the Full load amp figure is 23.6amps for that compressor it should normaly run at about 75% of that or about 18 amps, the breaker size should also be that recommended by the manufacturer (the 30 amp outside disconnect MAY be correct).

The reason I am saying I doubt that the conductors are a 12/2 is that both the wires feature black insulation, I have never seen a 12/2 where both conductors are black. That is not to say that the wires are not 12awg, I just don't think that that is a 12/2 cable assembly.

Do you have either a picture of the data plate or the model number, the former should list the conductor and OCPD ratings, or if you have the model # you should be able to find a copy of the installation instructions on the web.

Regards

Gerry

[nbhi]

Gerry
They colored the white wire black.

[gbeaumont]

Originally Posted by nbhi

Gerry
They colored the white wire black.

Ah, OK that I couldn't see. Normally they just put a piece of tape on it to indicate an ungrounded conductor.

Regards

Gerry