Two Services?

[charlie b]

A private charitable organization to which I belong is considering adding lights to the parking area that serves the meeting hall. The hall is about 4000 square feet, and is about 30 years old. I volunteered to perform a service calculation, to see if the electrical system had the capacity to add the lights. I took off the panel covers (visual inspection only) to the two side-by-side panels located just inside from the meter?s location. Both panels have a 200 amp main breaker and 20 breaker positions. What I wanted to find out is which panel had the feed-through lugs that provided power to the other. The answer surprised me: neither!

It appears to me that the four wires (2 black, 1 white, and 1 bare copper) that enter the top of each panel come directly from the meter. I cannot verify that without tearing into the wall or opening the meter, and I am not qualified to do either task. Both panels have their neutral and ground busses bonded, and both have labels stating that they are ?service rated.? One panel has nothing but 2-pole breakers, and the other has a mix of 1-pole and 2-pole.

Is this a common installation? Is this a violation? Am I looking at two ?services? to the same building? What is the rating of the service (i.e., 200 amps or 400 amps)?

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Just as a side issue, I also discovered that a sub-panel located in a storeroom had neutral wires and EGCs tied to the same bus. I have already informed the hall manager that he needs to get an electrician out to fix that problem.

 

[don_resqcapt19]

Re: Two Services?

Charlie,
I don't see any problems. It is a single service with multiple disconnects as permitted by 230.71(A). Each panel would have its own set of service entrance conductors as permitted by Exception #2 to 230.40. 250.24(B) requires the grounded conductor to be bonded at each service disconnect. In my opinion this is should be a 400 amp service.
I do wonder about the bare conductor. There is no need for an EGC on the line side of the main bonding jumper.
Don

 

[goldstar]

Re: Two Services?

Charlie,

I know you already know this but if there's only one service drop to the building then you only have one service. Although I've never installed a service in this manner I've been told by several colleagues that the lugs in the 200 amp meter pan are rated for (2) 2/0 copper conductors. I find it difficult to believe because I have a tough enough time getting one wire under the lug without sometimes smashing my fingers to ribbons. The service conductors in the riser ( and triplex depending on the utility company) should be larger than the individual load conductors to each panel. I've only seen one 400 amp overhead service in my area and the riser is a 3" PVC with 350 MCM conductors in it. I don't know what size the triplex is but it looks larger than any of the drops to residences that I've seen.

[ May 12, 2004, 06:40 PM: Message edited by: goldstar ]

 

[charlie b]

Re: Two Services?

Thanks Don and Goldstar. The next time I am at the hall, I will try to get a photo of the inside of all three panels. I am fairly certain that the bare copper wires entered the panels from the same conduit that had the service conductors. But I did not look for the grounding electrode(s), so I don?t know exactly where the bare copper wires go to.

I could not read the wire size on the insulation of the service cables. But I also have a hard time believing that each of the meter terminals could handle two wires the size of the ones I saw.