AC unit wired directly to Electric Meter

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Old 08-18-20, 07:35 AM
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AC unit wired directly to Electric Meter

My AC unit is not wired into the main house electrical panel, instead it is wired to a disconnect switch outside and then directly into the electric meter box (see attached pictures). Is there a breaker inside this box, and is this normal practice? House was built in 1994.

Thanks,

Scott





 
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Old 08-18-20, 07:41 AM
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There is no breaker in the meter socket. The AC disconnect better be fused.
 
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Old 08-18-20, 08:27 AM
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Open the disconnect, tell us what you find. There should be fuses or a breaker in there.
 
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Old 08-18-20, 08:40 AM
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Yes, you guys are right, there are fuses in the disconnect box.
 
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Old 08-18-20, 09:05 AM
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Thanks a lot, didn't even think to take off the plastic cover inside the disconnect box to see what was behind there, just thought it was a switch only.
 
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Old 08-18-20, 10:36 PM
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AC unit wired directly to Electric Meter
Wow..... that is illegal and against code.
Not good for a house built in 1994.

You'd better hope it's on the metered side or you'll get a surprise one day.
 
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Old 08-19-20, 07:35 AM
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Hi, you might try shutting everything off in your panel and only turn your AC on and see if the meter reads anything, you better hope it does, or like Pete said you could be in for a surprise.
Geo
 
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Old 08-19-20, 12:37 PM
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If the meter socket is double lug what code does it violate?
 
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Old 08-19-20, 01:24 PM
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If the meter socket is double lug what code does it violate?
You're kidding me...... right ?
How about the code of common sense.

Apparently this connection was tolerated back in the 50's. It was wrong then and is wrong now.
Connecting #10 wiring to an unfused source is just wrong. It doesn't matter if the meter is double lugged.

230.82 Equipment on the Supply Side.
Electrical equipment must not be connected to the supply side of the service disconnect enclosure, except:
(2) Meters rated not in excess of 600V.
(4) Tap conductors for legal and optional standby power systems, fire pump equipment, fire and sprinkler alarms, and load (energy) management devices
 
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Old 08-19-20, 05:14 PM
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If the meter socket is double lug what code does it violate?
It appears to be a 200 amp meter socket. I have never seen a 200 amp socket with double lugs. I'd like to see inside the socket and am pretty sure we would see conductors double lugged in single lugs.

I also question the wiring of the condensing unit with greenfield.
 
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Old 08-19-20, 05:21 PM
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So much for services being grouped.
 
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Old 08-19-20, 05:26 PM
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You're kidding me...... right ?
How about the code of common sense.
No, I'm not kidding. It was a honest question. So you don't need to be condescending. I figured since the supply conductors looked like they are within the max length of unfused conductors and are servicing a fused disconnect that it could be okay under 230.82(1) as a current limiting device.
 
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Old 08-19-20, 05:29 PM
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So much for services being grouped.
Yes that is a code problem for grouping the disconnects.
 
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Old 08-19-20, 06:53 PM
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I wouldn't be surprised if the wires are connected to the line side of the meter and they are stealing power. I am also wondering what that other cable is coming out of the meter?
 
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Old 08-19-20, 07:59 PM
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The larger cable is the service..... line to the panel.
 
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Old 08-24-20, 05:59 AM
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Here is a picture of the inside of the fusible disconnect switch box. Definitely not stealing power, my electric bill when the AC is running verifies that! From what I can tell, either has to be wired to a properly sized circuit breaker or with a fusible disconnect.

 
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Old 08-24-20, 12:17 PM
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Ok..... in the picture is a fusible disconnect. The gray service cable on the left is the feed from the meter. When connecting anything to the meter directly...... it's before your main panel and protection. That means that piece of gray cable is protected to roughly 400A as that's what an unfused service can deliver. That gray cable should have been connected to a 2P30A breaker in your house panel.
 
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Old 08-24-20, 12:27 PM
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Yes, not sure why it was not wired from the panel in the house, this is how I would have done it. AC was already there when I bought the place.
 
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Old 08-24-20, 01:15 PM
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Ok..... in the picture is a fusible disconnect. The gray service cable on the left is the feed from the meter. When connecting anything to the meter directly...... it's before your main panel and protection. That means that piece of gray cable is protected to roughly 400A as that's what an unfused service can deliver. That gray cable should have been connected to a 2P30A breaker in your house panel.
Technically I disagree. That is no different than the service conductors from the meterbase to a 200A main breaker. The service entrance conductors are rated at 200A and the main breaker is the current limiting device that limits the load to 200A. Tap conductors are allowed off the meterbase if serving a current limiting device, which is the fused disconnect. The fact that the service can deliver 400A means nothing when the fused disconnect limits the load to 30A. Conductor size is determined by loads not what the service can potentially deliver. I'm going off of NEC 230.82(1) and 240.21(B)(5). Around here I have seen multiple times taps used off a double lug meter to serve an outbuilding. The key is that the total potential load of the main service entrance and the feeder tap does not exceed the rated size of the meterbase. This is not to say there are not places that don't allow this type of double connection at the meter.
Ideally I agree with you.
 
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Old 08-24-20, 01:53 PM
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Hi, where does this 400 Amps come from? Wouldn’t that be determined by the size of the pole Transformer serving the service .
Geo
 
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Old 08-24-20, 02:20 PM
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One thing about the feeder tap that I think it needs is better protection such as being in RMC from the meterbase to the disconnect. Same goes for the service entrance being that low and exposed.
 
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Old 08-24-20, 03:02 PM
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Yes.... the potential 400amps is determined by the transformer and it's fuse.
Many transformers are sized to run 3-5 houses.
 
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Old 08-24-20, 03:19 PM
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Wouldn’t that be determined by the size of the pole Transformer serving the service .
That is correct, and the short circuit rating would be determined by the transformer impedance. For example, I installed a 200 amp 120/240 single phase service at a storage building. According to the power company, the impedance of the transformer was 1.6 ohms which calculates out to 5,703 amps for a line to line fault and 8,555 amps for a line to neutral fault. This is well past the 400 amps others have mentioned.

So the A/C disconnect is connected directly to the meter which makes the A/C disconnect another service. The two other things wrong I see here is the already mentioned fact that the two services are not grouped (230.72(A)), and the fact that the minimum service rating of a single-family dwelling is 100 amps. 230.79(C)

Also if this is a new house why is the A/C fed with FMC? FMC hasn't been allowed outdoors for at least 3 code cycles (9 ish years) or more.
 
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Old 08-24-20, 03:30 PM
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That tap is not a dwelling service under 230.79(c) it's a single circuit installation 230.79(a) which is 15A. Plus I'm not sure the disconnect grouping applies to this.
 
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Old 08-24-20, 06:55 PM
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FYI, house was built in 1994.
 
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Old 08-24-20, 06:58 PM
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That tap is not a dwelling service under 230.79(c) it's a single circuit installation 230.79(a) which is 15A
It is not a tap, it is a service. A tap would have overcurrent protection on the conductor being taped.

Is it on a house? (Yes) Then it is a dwelling service.

Plus I'm not sure the disconnect grouping applies to this.
230.72 pretty much applies to all services of a structure, whether it is a house or a high rise building.
 
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Old 08-25-20, 06:54 AM
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It is not a tap, it is a service. A tap would have overcurrent protection on the conductor being taped.
Is it on a house? (Yes) Then it is a dwelling service.
I misused the term "Feeder Tap" when saying what the service feed was from the meter to the A/C condensing unit. But I disagree that the service feed to the A/C by definition for application of the code is a dwelling service because that service feeder doesn't supply power to the physical dwelling(building) via the main service panel. It is no different than if that service feeder ran out to a well pump hundreds of feet from the dwelling, The mere fact that the service source and the A/C disconnect are mounted on the house doesn't define it as a dwelling service, it needs to supply power to the physical dwelling. If not. then what's the point of NEC 230.79 listing different ratings of service disconnecting means?
 
 

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