240v A/C interruptible service

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torint

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In the Detroit area I have been noticing a lot of interruptible A/C units have been installed over the years. I have noticed one thing that has me stumped, it has to do with grounding.
There is a separate meter for the A/C unit. From the load side of the meter, the conductors go to a 40a disconnect( two hots and one neutral ). The disconnect then feeds the A/C unit. It seems to me that the 40a disc is now a "main shut off". Should there be a grd rod? Should there also be a grding wire to the water meter?
 
Re: 240v A/C interruptible service

You are absolutely correct. In addition, there are now two wires under the same lug in most cases, in violation of 110.14(B).

I suspect that the electric utility wants to do this to keep from building more power plants, using larger substation transformers, building more substations, keep from building more primary circuits, etc. As a result, either they (who know very little about premises wiring) or a contractor who is doing the installation without a permit or inspection for the utility is getting by with this work. HMMM . . . I think I may be talking too much. :D
 
Re: 240v A/C interruptible service

You say a separate meter where does the power come from? Example from load center having a two pole breaker rated at 40 amps. Again what feeds this meter?
 
Re: 240v A/C interruptible service

Yeah I see these all the time. I think they are stupid and ugly and of course when its real hot they shut off the ac.

The two wires under the lug is a violaiton but i dont think the utility goes by the nec and since the illegal connection is on the LINE side its is there property.

You guys are saaying the ac disconnect is a service disconnect and should be bonded to the GEC? I would agree. But I have seen hundreds of these hooked up this way without any connection to the gec and I doubt there wasn't a permit on a single one.
 
Re: 240v A/C interruptible service

Runkle: There are two separate POCO meters. The riser comes to the 1st meter and then there is a 1" nipple between the meters which allows cdrs to jump from the line side of meter #1 to the line side of meter #2. usually using #8awg cdrs. I went to the POCO yesterday to order a case of meter cans because I'm doing a service change soon. I asked for a meter can with double lugs so that the installation is code compliant. The counter person said that they don't make them. This was at the Detroit Edison service center.

[ July 29, 2004, 09:04 AM: Message edited by: torint ]
 
Re: 240v A/C interruptible service

Most of the electric utilities (including mine) stop at the service point and that is where the service drop stops (or service lateral) and the service entrance conductors are in the jurisdiction of the AHJ (this includes the connections in the meter fitting). If this is a lateral, we could place two wires under the line lugs. IMO, that is not a good idea since, in most cases, Cu wire will be used with the Al wire.

All in all, this is not good. BTW, the main disconnecting means is normally inside and the AC service main disconnecting means is outside. All the installation is in the AHJ's jurisdiction except the connection on the line side of an UG fed meter fitting.
 
Re: 240v A/C interruptible service

Well grounding will be one of the violations here is another grouping of services. The situation you describe sounds like utility load management. I would wire as follows the main meter can would feed the service a properly sized circuit breaker would sub feed the a.c. through another meter can located next to the main meter can, both would be label as such. then the utility can do the math and give the proper discount.
 
Re: 240v A/C interruptible service

William if someone did it your way the utility would just charge you twice. They would never go for special exceptions for how you want to hook it up.

I think the way it shoul be hooked up to be code compliant is like they would do it on a duplex with multiple meters.
 
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