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ryan14
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# Posted: 11 May 2014 09:05pm
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Hello, I am new to the site and am hoping someone can help with an electric service question. My wife and I purchased a camping cabin and it is being delivered tomorrow (weather permitting - fingers crossed!) Pictures as soon as I can...
So it comes with a 100 Amp main breaker box inside the cabin. There is conduit run from breaker box to outside which is how we would feed the service wire in to cabin from meter. Everything will be underground from main pole at the road.
Electric co-op wants a 200amp meter box and disconnect installed on a 6x6 post because the cabin isn't considered permanent due to it only sitting on a gravel pad. They gave us a customer requirement sheet but it doesn't answer my question below.
My questions - for future electrical needs (shed, pavilion, etc.) I have seen other setups where there is another box mounted to the pole just below the meter with conduit coming out of it feeding other places like i want but i dont know what that other box is called. I assume this other box has breakers in it. Is that the disconnect? Would my main breaker inside the cabin feed from this other box on the pole? I am hoping i attached this picture correctly. It is an example of the box below the meter
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bldginsp
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# Posted: 11 May 2014 09:34pm - Edited by: bldginsp
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Hi Ryan, welcome to the site.
The box below the meter enclosure is just a breaker panel. But, because that breaker panel is part of the service equipment, it has special rules that apply to it. Yes, that is your main disconnect and must have a single switch that cuts off all power, or no more than six total switches to cut power to all that feeds off the box. That box is where all power is fed from, so any circuits or feeders you want to power up will have to go there in conduit.
The feeders that come off this service panel to feed your sub panel inside are technically not service conductors, they are feeders. The difference is that they begin from a circuit breaker that you are in control of, inside the service equipment. The service conductors that come into the service equipment and provide power to the breakers begin somewhere where you don't have control and you can't shut them off. So if they go haywire your breakers don't shut them off. That's why services have special grounding and bonding rules, for safety in case the service conductors insulation wears thru and power gets out.
So you will have a breaker in the service box that feeds the feeders that run to your sub panel in the cabin. Because your cabin will be separated from the service enclosure, the sub panel in the cabin must have its own ground rod.
The service enclosure doesn't have to have a separate meter enclosure and breaker panel. They make them as one box, which I'm sure you've seen. You can do it either way, either way both or one constitutes the service and has to meet those requirements.
I don't think they should be able to require you to set a 200 amp panel. You'll never use close to that if you just have a cabin and a pavilion. The electrical code only requires 100 amps minimum for residences. You should push them on that. No need to spend extra for capacity you will never use. The difference in cost between a 200 amp service panel and a 100 amp is not that much, but you are probably paying for the cost of the service conductors from the pole on the road to the service panel. 100 amp conductors will cost a lot less than 200 amp.
By the same token you don't necessarily need to provide 100 amps into the cabin. The panel in the cabin is rated at that, but you'll never use that much unless you have elec stove, AC, electric dryer and three hair dryers running all at once. If all you need is lights, stove and TV you'd be fine with 60 amps, in which case the breaker in the service panel for the cabin only needs to be 60 amps and the feeder wires from that breaker to the panel inside can be 60 amp rated as well, much smaller and cheaper than wire rated for 100 amps.
Hope this helps
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old243
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# Posted: 11 May 2014 11:21pm
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possibly the utility is asking for the 200 amp, meter disconnect , if they are feeding the service , underground and their minimum cable size is 3/0 or 4/0. This would allow for 2 inch hubs or knockouts to accommodate the large size wire . also the connection lugs in the base or disconnect would accommodate the larger cable.
Our utility used all 3/0 ugnd, required a 200 amp base , it could then be reduced beyond the meter to 100 amp.
I guess it depends on the supply authority , policies and inspection requirements.
As far as the cable from the disconnect to your cabin, I would be inclined to run it by the local inspector . If they would accept 60 amp feeding the cabin , in which case you would use 6x3 ugnd cable , or 100 amp using 2x3 ugnd cable. No sense fighting with the hydro inspector, get his opinion prior to going ahead. Opinions cost nothing and he might answer other concerns you might have.
I spent 35 years in the electric utility field , managed the local utility and dealt with inspection on a daily basis. Good luck with your project
old 243
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ryan14
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# Posted: 12 May 2014 10:37pm
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Thank you for the replies. Definitely got me pointed in the right direction!
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toyota_mdt_tech
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# Posted: 13 May 2014 09:04am
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I also think you will run 4 wires, ie line, line, neutral and ground. The neutral and ground will be bonded at the main service panel, the feeder panel and ground wil be isolated and as bld insp mentioned, a separate ground rod. You wil need to purchase a grounding bar for the inside of your panel. They have a spot where they fit right in and remove the green screw that bonds the neutral and ground inside the panel to isolate them.
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old243
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# Posted: 13 May 2014 09:28am
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A further advantage of having 200 amp capacity , available at your main breaker, is down the road you might decide to build a garage or shop , or whatever. you would have lots of capacity to set up a cottage industry. Not sure what your plans are , this leaves options.
Like the other posters have said , code in different areas vary a bit , so get your info correct for your area. Old 243
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MtnDon
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# Posted: 13 May 2014 09:39am
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It would not surprise me if the utility company has a rule that you must have a 200 amp service to the meter.
Then it would also not surprise me if the building permit folks had their own rule for certain size service panels, which may be partly dependant on the square footage of the cabin/home. They may very well have a minimum amperage.
It's all setup to look out for having adequate service size based on averages and avoid circuit overloads. As has been pointed out a few times; different rules in different places. So "let your fingers do the walking".
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