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Wiring a 30A Disconnect

Posted by garlicjim (My Page) on
Wed, Mar 3, 10 at 17:32

Well, I got the 220 wiring to the AC unit, but was told I must have a "disconnect" near the unit. That was news to me, but I got one and now I need to know perzactly how to wire it.

It's the one with the fuses.

My question is: Does both the incoming hot wires connect to
the top bar and the outgoing two hot wires connect to the bottom bar? Does it matter if they are reversed?

Or does one incoming hot connect to the top and the other to the bottom and the same for the outgoing hot wires? That wouldn't make sense to me, but I'm thick headed .

Thanks for your help.

Jim


Follow-Up Postings:

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RE: Wiring a 30A Disconnect

Line in on top. Load out on the bottom. Does not matter which hot is where.

Fused was not necessary, but since you have it, use it.
Size the fuses according to the sticker on the unit.


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RE: Wiring a 30A Disconnect

I found an electrician who said that he would put INCOMING on top, just for his own edification, but that it didn't really matter. I guess there are no one way streets, eh . He did say to keep the color on the upper and lower the same.

Why wasn't the fuses necessary? I wasted four bucks .

Thanks,

Jim


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RE: Wiring a 30A Disconnect

Incoming would be the same as "line".

The colors DO NOT matter, other than personal preference. Given the choice I would also match them, but I would not go out of my way if I had to for some reason.


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RE: Wiring a 30A Disconnect

You have a 30 amp circuit breaker already so fuses are redundant.

The reason for the disconnect is that anyone servicing the unit can turn it off and physically see that it stays off.


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RE: Wiring a 30A Disconnect

But without the fuses, there is no "connect". Am I wrong?

I looked for a fuseless disconnect, but all I could find was a 60 Amp model at a number of retailers, so I got to thinking maybe there isn't a fuseless 30 Amp model.

Anyway, got it and got it wired. Ready for the AC folks wire it into the unit.

Regards,

Jim


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RE: Wiring a 30A Disconnect

And it never occured to you that the 60amp non-fused would handle the 30amp load. No fuses to buy or higher price for fusible disconnect.


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RE: Wiring a 30A Disconnect

It occured to me, but the electrician who first told me I needed the disconnect said the 60 Amp wouldn't work. As I'm getting to understand it more, it seems it would make perfect sense since, under normal circumstances, the disconnect isn't even needed. I don't even know if it actually was required, but he told me I had to have it according to code. Where I live, I really don't care about code, anyway, but they were licensed contractors and they cared.


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RE: Wiring a 30A Disconnect

The disconnect is required by code for the reasons given (you can turn it off at the unit and know that some moron isn't going to power it back up while you're working on it).


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RE: Wiring a 30A Disconnect

Yes, the disconnect was required.
Yes, you should care about codes regardless of where you live.
No, the guy who told you a 60A disconnect would not work is hardly an electrician.

A 60A non-fused disconnect is standard issue for most A/C units.

Glad you got it working.


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RE: Wiring a 30A Disconnect

As I think of it, the size of the disconnect isn't an issue because if there's a problem the breaker in the sub-panel would trip. Any you're correct the dude isn't an electrician, but he's going to school and knows just enough to be danger-ous . Nonetheless, he's who the AC installers use, so
I figured I'd better use his advice. He also told me that I needed to use a different wire to the unit from the disconnect and that it needed to be in a flexible shield. That wasn't a problem because I had the wire and they'll furnish the shield. Folks down in this neck of the woods can't always seem to get things right. Bob'll say something and then Ray'll say something else. But they got themselves a varmit that demands and will get what he has coming one way or another. The guy that gave the estimate, for example, promised to add an additional vent in the dinning room, which had been added on since original construction
(just having air added to an existing central heat system). His work partner said they couldn't do it (and gave a good, understandable reason), but I told him there "ain't no such word as "cain't"; to "find" a way to do it! They have to finish today, so we'll see. I have an idea or so myself.


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RE: Wiring a 30A Disconnect

Please correct me if I`m wrong. NEC 440.14 " disconnecting means shall be located within sight..." So an outside panel located within site of the a/c meets code. A disconnect close to the a/c is not required by code if the panel is within sight.


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RE: Wiring a 30A Disconnect

Depend on the AHJ, where I am (Austin,TX) you Must have a disconnect and it MUST be fused no matter if the Panel is in sight.


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RE: Wiring a 30A Disconnect

To Saltceder: When you say"MUST" is it by the AHJ, or by the Code Book?


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RE: Wiring a 30A Disconnect

AHJ


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RE: Wiring a 30A Disconnect

File a formal complaint in writing with the head of the AHJ inspectors.

Inspectors are not allowed to just make up rules as they see fit.


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RE: Wiring a 30A Disconnect

Sorry, I misinterpreted the question. I believe it's a local code,
not the inspector. We did have a local sparky on this board
so I hope they will chime in on this.


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RE: Wiring a 30A Disconnect

For a while AC condesnsors did not have a listing that allowed circuit breakers, and fuses were then required.

Every one I have seen or installed for at least the past 5-10 years has allowed the use of a HACR (Heating Air Conditioning Refrigeration) rated breaker, making the typical outside box just a disconnect.

Most residential breakers are HACR rated, so they can serve as the overcurrent protection device for the branch circuit feeding an AC condenser.

It does pay to make sure the breakers are rated if the panel is old and equipment is being changed.


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RE: Wiring a 30A Disconnect

Can I come in a 30 amp disconnect on the line side with 10 wire but the load side is used with 12 wire?


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RE: Wiring a 30A Disconnect

No, you can't.


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