Several AHU in a single circuit

[tomito]

Hello, recently I did an electrical project for a gym and I connected 3 air handling units in the same circuit (2.5 A each, 208 V, single phase) I used a 2P-15 A breaker (to comply whith 430-53 a)) and a disconnect at each unit.
The AHJ says this is against code, that you must comply with art 440 and not with 430, what do you think? I have done this before and in an another project and the AHJ (different to this) didn´t say anything about it.

Thanks
Tom

 

[tomito]

Found my own answer... 440.3 B)

Thanks anyway....
Tom

 

[suemarkp]

Does it matter if 440 also applied? I thought 440 also allows multiple AC units on a single branch circuit if that circuit happens to be large enough and the breaker is within MOCP limit of all units. This would make sense if you had a couple of small mini splits on one circuit.

 

[tomito]

Does it matter if 440 also applied? I thought 440 also allows multiple AC units on a single branch circuit if that circuit happens to be large enough and the breaker is within MOCP limit of all units. This would make sense if you had a couple of small mini splits on one circuit.

I tough the same but the AHJ said there are no rules allowing this on 440 like there is on 430.

 

[suemarkp]

You don't need a rule allowing it, they need to show a rule prohibiting it. I don't know of such a rule in 440, but it's a long chapter and I don't know everything...

 

[tortuga]

Hello, recently I did an electrical project for a gym and I connected 3 air handling units in the same circuit (2.5 A each, 208 V, single phase) I used a 2P-15 A breaker (to comply whith 430-53 a)) and a disconnect at each unit.

I agree this is allowed as long as the 430.53(A) 1-3 are met, Inspector is mistaken.

The AHJ says this is against code, that you must comply with art 440 and not with 430, what do you think?

In the 2023 they deleted 440.3, not because 430 does not apply rather it was redundant per Article 90.3, so throw anything in 430 or 422 at your install and if it sticks go with it.

 

[kwired]

I tough the same but the AHJ said there are no rules allowing this on 440 like there is on 430.

If this is air handler only and has no hermetic compressor then 440 does not apply. 422 does apply, which could still send you to 430 for some things.

But I also can't see how this setup would be prohibited even if 440 was applicable.

 

[tomito]

Thanks guys, I´m still waiting for an answer from the AHJ about it, I Just told him to read 430.3 B) and that this equipment does not have an hermetic compressor.

Tom

 

[tomito]

Hello again, so finally I got an answer from the AHJ, he said that the condensing unit and the AHU it's one equipment because the AHU can't do the job (cool the area) without the condensing unit working, I explain to him that electrically they are separated, every equipment are feeded from an independent circuit breaker and that the AHU can work without the CU. He did not accept the explanation. What a joke!

Thanks guys!
Tom

 

[chicar]

You can have a AHU running just for air circulation. Why is he acting like that ???

 

[tomito]

You can have a AHU running just for air circulation. Why is he acting like that ???

I told him that too, I guess he doesn't like somebody tells him that he's wrong.... maybe
.

 

[tortuga]

If this is air handler only and has no hermetic compressor then 440 does not apply. 422 does apply, which could still send you to 430 for some things.

But I also can't see how this setup would be prohibited even if 440 was applicable.

The way 90.3 is worded, as I understand it, all the requirements in chapter 4 apply generally, and articles in chapter 4 cannot modify other articles in chapter 4. So anything in 422, 430, or 440 that can apply to the AHU does apply.

 

[kwired]

The way 90.3 is worded, as I understand it, all the requirements in chapter 4 apply generally, and articles in chapter 4 cannot modify other articles in chapter 4. So anything in 422, 430, or 440 that can apply to the AHU does apply.

No time to look at the moment, but pretty certain both 422 and 440 refer you to 430 for certain things. This may not really be a so called modification but rather certain aspects are covered by rules in 430.