Mr. Serious
Senior Member
- Location
- Oklahoma, USA
- Occupation
- Electrical Contractor
We have a customer who is buying a 200A generator to back up his whole house. But after the service has been partially built, coming underground from a pole about 300 feet away to the location on the house where the power company wants the meter, the customer may want to change things.
As initially designed, the service point would be the meter on the house, then I would put a service-rated automatic transfer switch next to the meter on the outside of the house, the generator company would put the generator there next to the house, and I would put the main panel right inside the house. The main panel is already done, and we kept the neutrals and grounds separate within it. Initially there was some talk of using a special meter can that had the transfer switch built in, that the generator company would provide. After some delay, the power company finally said they won't accept that special meter can.
The customer dislikes the idea of having the generator next to the house, plans to eventually build a barn on the property about 75 feet from the power pole but in a different direction from the power pole. So, we started talking about other options, and one that came up would be for him to change the service to 300 or 400 amp built on a rack near the pole, and convert the underground wire that the power company just installed to a feeder instead of the utility company service wires. Put the generator and the transfer switch out there at the pole. Then perhaps his house and his barn could both be backed up, although we did already realize that would require two transfer switches even if it's just one generator, since they'll be separate feeder breakers.
The main sticking points are:
1. The power company doesn't seem to like that idea, they don't want to change what they've already planned to do.
2. There are just 3 wires in the ground, there wouldn't be a way to separate the ground and the neutral conductor.
I know #2 means the installation is against code, since 2008 or whenever you can no longer have a 3-wire feeder to a separate building, but the thing is, in rural areas around here the inspectors still allow it. So I believe the inspector would allow it. I would of course ask the inspector first before we go down this route, and the customer would still have to work things out with the power company, but my question is, how objectionable is it, really, to have a house fed with 3 wires on a rural property? I would re-ground the neutral at the house, and obviously there would be some objectionable ground current, but rural services with a house and a garage are often built that way and they still allow it. I wouldn't build it that way, but I don't want to change an existing 300-foot long underground feed. And, does it really change things at all, to add a backup generator out there? In terms of making it more wrong than it already was?
As initially designed, the service point would be the meter on the house, then I would put a service-rated automatic transfer switch next to the meter on the outside of the house, the generator company would put the generator there next to the house, and I would put the main panel right inside the house. The main panel is already done, and we kept the neutrals and grounds separate within it. Initially there was some talk of using a special meter can that had the transfer switch built in, that the generator company would provide. After some delay, the power company finally said they won't accept that special meter can.
The customer dislikes the idea of having the generator next to the house, plans to eventually build a barn on the property about 75 feet from the power pole but in a different direction from the power pole. So, we started talking about other options, and one that came up would be for him to change the service to 300 or 400 amp built on a rack near the pole, and convert the underground wire that the power company just installed to a feeder instead of the utility company service wires. Put the generator and the transfer switch out there at the pole. Then perhaps his house and his barn could both be backed up, although we did already realize that would require two transfer switches even if it's just one generator, since they'll be separate feeder breakers.
The main sticking points are:
1. The power company doesn't seem to like that idea, they don't want to change what they've already planned to do.
2. There are just 3 wires in the ground, there wouldn't be a way to separate the ground and the neutral conductor.
I know #2 means the installation is against code, since 2008 or whenever you can no longer have a 3-wire feeder to a separate building, but the thing is, in rural areas around here the inspectors still allow it. So I believe the inspector would allow it. I would of course ask the inspector first before we go down this route, and the customer would still have to work things out with the power company, but my question is, how objectionable is it, really, to have a house fed with 3 wires on a rural property? I would re-ground the neutral at the house, and obviously there would be some objectionable ground current, but rural services with a house and a garage are often built that way and they still allow it. I wouldn't build it that way, but I don't want to change an existing 300-foot long underground feed. And, does it really change things at all, to add a backup generator out there? In terms of making it more wrong than it already was?
