Outdoor Condensing Units Over Protected...

[Cody Atkinson]

What is the general rule of over protection in a panel for outdoor condensing units? Outdoor condening unit max breaker is 40 and in the panel it shows 45. I've always marked this over protected, but electricians say this is not the case. Help Please...

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[Ted Menelly]

What is the general rule of over protection in a panel for outdoor condensing units? Outdoor condening unit max breaker is 40 and in the panel it shows 45. I've always marked this over protected, but electricians say this is not the case. Help Please...

If max breaker is listed on the manufacturers tag at 40 then it is 40 and anything over is over and needs to be replaced. They are already listing the over protection as you call it. The unit probably never needs the 40 amp but at start up or high load times it is needed. Anything over that and you can damage the unit before the breaker kicks off.

Again, over is over, it needs replacing.

[Cody Atkinson]

Thanks Ted...I will keep doin what 'm doin...

[Jim Port]

Seems strange as a 45 is not a common breaker ampacity.

If there was additional overcurrent protection of the proper sizing it would be fine.

[Rick Hurst]

Cody,

I saw one today with a 60amp when the label called for a maximum 40amp.

And to make it worse, it was in a Federal Pacific Stab Lok panel located in a master bedroom closet. The panel door would not close, 220amp breakers were missing bridge ties, nuetrals to 220's not identified properly and to top it off there was paint sprayed all over the buss bar, wiring and the breakers

rick

[Rick Hurst]

Seems strange as a 45 is not a common breaker ampacity.

If there was additional overcurrent protection of the proper sizing it would be fine.

Thats what they had on the truck that day.

[Scott Patterson]

Seems strange as a 45 is not a common breaker ampacity.

If there was additional overcurrent protection of the proper sizing it would be fine.

Actually it is a common size with HVAC systems. Problem is that when the electrical is run, the electricians stick in whatever they have on the truck that is close to what the manufacturer requires. They never have anything but the standards in the truck.

If the data plate says a 45 amp, it needs to be a 45 amp breaker. No larger or smaller. If the ole home inspector goes by what the manufacturer requires then everyone will be happy. Well, almost everyone!

[Billy Stephens]

Cody,

I saw one today with a 60amp when the label called for a maximum 40amp.

And to make it worse, it was in a Federal Pacific Stab Lok panel located in a master bedroom closet. The panel door would not close, 220amp breakers were missing bridge ties, nuetrals to 220's not identified properly and to top it off there was paint sprayed all over the buss bar, wiring and the breakers

rick

.
There You Go Again Mr. Nit-Pickey Deal Killer.
.

[Jim Port]

If the data plate says a 45 amp, it needs to be a 45 amp breaker. No larger or smaller. If the ole home inspector goes by what the manufacturer requires then everyone will be happy. Well, almost everyone!

Actually the nameplate will say maximum breaker size. A lesser ampacity could be installed and be compliant, but may trip on startup.

[Jim Luttrall]

Most manufacturers now list both a minimum and maximum breaker requirement. Keep it between the ditch on both sides of the road. Too little and it will trip under heavy loads, too big and it won't trip when it needs to for the protection of the compressor.

[Jerry Peck]

Most manufacturers now list both a minimum and maximum breaker requirement. Keep it between the ditch on both sides of the road. Too little and it will trip under heavy loads, too big and it won't trip when it needs to for the protection of the compressor.

Jim,

I've seen labels which state maximum and minimum breaker sizes, just not many, and (unfortunately) not the one you posted either.

The one you posted states the minimum circuit ampacity and the maximum overcurrent rating size.

Not the minimum overcurrent rating size.

[Jim Luttrall]

If the circuit supplies the minumum ampacity then by default, the OPD must supply at least the minimum specified. That is the ditch on one side of the road with the maximum breaker on the other side.
I see what you are saying Jerry, let's not strain at gnats for once.

[Jerry Peck]

If the circuit supplies the minumum ampacity then by default, the OPD must supply at least the minimum specified.

Nope.

The minimum ampacity is for the minimum size rating of the conductors, it has nothing to do with the size of the overcurrent protection device.

You could install a 30 amp rated circuit if it called for a 29.7 amp minimum ampacity and then install a 20 amp breaker on it and meet the nameplate requirements. It might not start up with a 20 overcurrent device, but it would meet the nameplate requirements.

I see what you are saying Jerry, let's not strain at gnats for once.

Not straining anything, simply trying to pull you back from what you think is a ditch and it is really just a hedge along a cliff.

[Jim Luttrall]

If you install a 20 amp breaker, the circuit cannot supply the minimum 29 amps. The wiring and everything else may be capable, but the CIRCUIT which includes the OPD cannot supply the minimum required by the manufacturer.
From the label I posted, what bottom limit would any competent electrician use if he did not have the 40 amp maximum breaker?

[Jerry Peck]

Jim,

Read that label again.

"The circuit" is there whether or not an overcurrent protection device is installed.

"The circuit" must have that minimum ampacity, meaning "the circuit conductors".

The overcurrent protective device has nothing to do with "the circuit ampacity", only with the level of protection placed on that circuit.

[Jim Luttrall]

From the label I posted, what bottom limit would any competent electrician use if he did not have the 40 amp maximum breaker?

[Jerry Peck]

From the label I posted, what bottom limit would any competent electrician use if he did not have the 40 amp maximum breaker?

Competence has nothing to do with it.

If the electrician did not have a 40 amp breaker, the MAXIMUM size allowed, the electrician would likely put in a 30, hoping that it would hold until he could replace it with a 40 amp breaker.

If he did not have a 30 amp breaker, he would put in a 20 amp breaker and cross his fingers that the breaker would not trip on start-up while he runs out to get a 40 amp breaker.

That "Minimum CIRCUIT Ampacity" has nothing to do with the overcurrent device size used, only the MAX. FUSE OR MAX. CKT. BKR (HACR TYPE per NEC) 40 amp has anything to do with the overcurrent device rating.

[ken horak]

*****

[Rollie Meyers]

Most manufacturers now list both a minimum and maximum breaker requirement. Keep it between the ditch on both sides of the road. Too little and it will trip under heavy loads, too big and it won't trip when it needs to for the protection of the compressor.

The Unit in the picture, could be supplied w/ 12 AWG on 40A OCP. and be code compliant, wire for minimum & overcurrent protection to the max.