That A/C Condenser Breaker Oversized?

[@elamarrlamarr6282]

Keep moving forward and do what you've been doing because you've been a blessing to many and when you're doing the right thing you will get negative comments and negative people to help discourage you from the truth

[@PPG1967]

I really appreciate you saying that...thanks for watching!!

[@JohnsonMiningCompany]

Hey man, I love your channel. Been a subscriber for a while. This is not controversial in any way. . Max fuse size listed on the manufactures nameplate is the size breaker of fuse that needs to be installed. Period. End of story. Under sizing well cause constant tripping. As everyone is aware, the starting amp draw of a condenser can be up to four times or more what it shows as minimum circuit ampacity. A 15 amp HACR or TDR type fuse will blow as ac condensers will draw the excess amps for a much longer time when starting than a typical electric motor. I can’t tell you how many times I’ve went out on a service call because my new unit is blowing fuses only to find out the electrical contractor installed fuses based upon MCA instead of max fuse size listed on the manufacturer’s nameplate.

[@PPG1967]

I appreciate your commenting, and thanks for watching!!

[@dcovatech]

No ambiguity about it. The values on the name plate are marked clearly, and your explanation is spot-on. By the way, I have never seen a cage around a residential unit. What is up with that?

[@PPG1967]

There's a huge condenser theft problem here in Atlanta.

[@PPG1967]

They steal condensers for the copper.

[@marshallwallace719]

Yes you are correct the max fuse or overcurrent protection device (MOP) is for the breaker size which protects the condenser. However the minimum circuit ampacity (MCA) is to determine the correct wire size. Example: The MCA listed on the nameplate = 28.6 amps. We then go to table 310.15 in the NEC and find the nothing less than a #10 Romex (NM cable) can be used on this condenser because a #10 wire is rated for 30 amps. A #12 wire would be too small because it is only rated for 20 amps. A #14 wire is rated for 15 amps etc. The MOP listed on the nameplate= 50 amps We then just go to the breaker/fuse for the condenser and check to make sure that it is not larger than the 50 amp MOP listed on the nameplate.

[@Mltemple8333]

Seems crystal clear to me, especially if you want to actually protect the circuit properly.

[@PPG1967]

I appreciate you watching!!

[@pixelatedmushroom]

Also oversized is the cost to install central HVAC these days.

[@PPG1967]

I appreciate your feedback, and thanks for watching!!

[@shortsilwady]

How would that look like? Do you mind sharing a link of a strap or example?

[@PPG1967]

I don't understand what you're asking..

[@marshallwallace719]

The minimum circuit ampacity is for the wire size. So 14.5 minimum circuit ampacity means a #14 Romex can run this system as it is rated for 15 amps. You have to look in the ampacity table in the NEC.

[@Calico5string1962]

The issue was with the feed breaker sizing, not the wire size. In fact, it would be intersting to know what the conductor sizing is, since they were feeding it with a 35A breaker. And, if it WERE wired using #14 wire, and being supplied by a 35A breaker, that could (would) be even a bigger problem. Also, you must include the inrush current and voltage drop into the conductor sizing, not just the minimum circuit ampacity. Lastly, the "circuit ampacity" always includes the breaker size feeding the circuit.

[@PPG1967]

Those numbers on the condenser nameplate (minimum & maximum amp) are there to protect the condenser. I don't understand why some people don't get this.

[@marshallwallace719]

@@PPG1967 Yes, you are correct the mop is to protect the equipment yes. However the MCA is really used to determine the wire size. Example: MCA= 28.6 from unit nameplate. This means you can use no less than a #10 Romex (NM) as it is rated for 30 amps. Look in the NEC Table 310.15.

[@marshallwallace719]

@@PPG1967 Yes you are correct the MOP (max fuse) is used to protect the equipment. However the MCA (minimum circuit ampacity) is really used to determine what the correct wire size should be. Example: Minimum circuit ampacity from the condenser nameplate = 28.6 amps Then we go to table 310.15 in the NEC and find that nothing less than a #10 Romex (NM) can supply this unit as a #10 is rated for up to 30 amps. A number #12 wire would be too small as it is only rated for 20 amps.

[@marshallwallace719]

Some nameplates will specify a minimum fuse but it will say minimum fuse not minimum circuit ampacity.

[@buck-johnson]

According to NEC (2014) Article 440.22 it says that it can be 175% of the nameplate rating, and if that isn't enough you can go to 225%, which is 45 amperes. 25A×1.75=43.75A ~ 45 amp breaker. It seems wrong that the breaker would be at the same value as the maximum load because you wouldn't want it to trigger at that point, only at a higher amount.

[@PPG1967]

Read 440.22(C) NEC 2017

[@buck-johnson]

@@PPG1967 Thanks, 2014 says the same thing, to use the upper value on the nameplate, just as you say in this video. 😀

[@Calico5string1962]

The "nameplate rating" specified in 440.22, would be referring to the combined RLA (Running Load Amps) of the compressor and condenser fan motors, as noted on the nameplate, not the "Max circuit size" rating on the nameplate. In fact, that "Max circuit size" data would likely include the necessary 150-175% over-current inrush allowance. Bottom line: The "MAX circuit size" is indicated as 25A, so the over-current protection should not exceed that. And that over-current protection can be either the breaker at the supply panel, or a fuse or circuit breaker at the equipment.... which is why I'm pretty sure that "switch" (equipment disconnect) at the the condensing unit, is in fact a circuit breaker (it is a Square-D type "QO" breaker, but can't see the ampere-rating on the handle, in the video). It may be the correct size...

[@PPG1967]

It’s not a circuit breaker. It’s just an on or off disconnect switch.

[@Clark-Mills]

Seems fairly clear; grab yourself a coffee! :) Thanks

[@PPG1967]

Much appreciated!!!

[@Calico5string1962]

But wait! That "disconnect" located outside at the condensing unit is, in fact, a 2-pole Square-D circuit breaker. So what is the amp rating on that breaker? If that "disconnect" breaker is rated between 15 and 25 amps (as per the min-max rating on the condensing unit) then the circuit would be compliant. Effectively, the condenser's supply max-ampere capacity would be limited to that device's rating. The upstream breaker (in the panel) could be nearly anything bigger, provided the conductor size is sufficient. And what size are the feed conductors, from the panel to the "disconnect? What size conductors are needed for a 35-amp breaker? (Bigger than #10...). Again: What size is that "disconnect"? Size matters! 😂😂

[@PPG1967]

That's a on/off switch.

[@Calico5string1962]

@@PPG1967 Sorry sir, but that's not just an "on/off" switch... It is clearly a Square-D, Type "QO" circuit breaker, in a Square-D NEMA 3R enclosure. I've installed many of these exact devices as AC disconnecting means (just as used here). If THAT breaker is properly sized, it becomes the over-current protection for the condenser/compressor, regardless of the size of the up-stream (panel) breaker. And it doesn't HAVE to be a fuse... a circuit breaker (properly sized) is absolutely permitted. However, the up-stream breaker's ampacity cannot be so large, as to not afford protection for the conductors between the panel and the AC disconnect/breaker. Furthermore, while the minimum & maximum circuit capacities are given on the name-plate (and these can be used for circuit sizing), as an electrician (which I am, 40+ years), it's still always a good idea to calculate the ampacity required using the FLA amp rating of the compressor and condensing fan, and applying the the multiplier (typically ~150%) to arrive at the required correct circuit & breaker sizing. The whole idea is to have sufficient circuit ampacity, to allow the high inrush currents associated with a loaded compressor starting, without tripping the over-current device, but also low enough to protect against an excessive overload (such as a "locked rotor" condition) which should trip the over-current device. That's why they list "FLA" and "LRA" ("Full-load Amps" and "Locked-rotor Amps) ratings on the condenser/compressor units. One additional thing: In your video, the breaker panel has a 35A breaker for the condenser... but what size are the conductors feeding the condenser? If they are #10 awg wires, then that breaker is too large. If they were #8 awg (or larger, but why) then it would be permitted. Anyway, always great stuff! Love seeing how new homes are built so poorly at times...

[@markbowker5936]

JUST FOR CLARIFICATION WAS THERE AND ON/OFF TOGGLE SWITCH AT THE DISCONNECT OR WAS THERE A DOULBLE POLE BREAKER THAT CAN BE TURNED ON AND OFF? SORRY, A LITTLE CONFUSED ON THAT POINT AS THE VIDEO IS NOT CLEAR. THANKS.....

[@daveaedion]

And by "on off switch" it says right on it that there is no overcurrent protection, it's literally just a switch that looks like a circuit breaker. As always, thanks for the time you put in making these videos.