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slim
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# Posted: 24 Jan 2015 16:24
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I have a pole building I will be supplying power to via generator (120/240 30amp) and power inlet box. It is off-grid. I plan on running wire from inlet box located outside, to a subpanel inside the bldg. My question..instead of having a separate main switch inside, can I run the leads from inlet box directly to a 30 amp double pole breaker instead of panel main lugs? This would mean that the busses that supply the individual circuit breakers would not be energized unless the 30 amp double pole breaker was closed (on).
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MtnDon
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# Posted: 24 Jan 2015 17:50
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You can. To keep it to code the breaker that is back fed is supposed to be secured to the panel so it can not be easily removed. There is also supposed to be a label indicating which breaker is backfed. This is all to prevent injury or death to a third party who has no idea that the service panel is not the usual thing.
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slim
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# Posted: 24 Jan 2015 18:59
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Good information MtnDon. That's important. Thanks.
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toyota_mdt_tech
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# Posted: 24 Jan 2015 20:28
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Can you just get a primary panel with the main already in place? It can be switched off and BUSS dead also. Like a 100 amp service panel? Interior, reasonably prices, not much $$$ and plenty of space later. The extra double pole with consume spaces. But you know what your requirements will be.
Yes, you can use a breaker, but as Don mentioned, it must be anchored in place. Usually there is a provision for a long screw between the 2 poles.
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Bancroft bound
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# Posted: 25 Jan 2015 08:26
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Check prices!!!
Unless you already have the panel, a lot of times a panel package deal, with a main, is cheaper than gathering all the parts separately.
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toyota_mdt_tech
Member
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# Posted: 25 Jan 2015 11:54
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And to add to Bancroft, the interior 100 amp panels have 8 breakers included already. (a mix of 15 and 20 ampers)
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Don_P
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# Posted: 25 Jan 2015 14:10 - Edited by: Don_P
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Not a sparky but I believe it'll take a 30 amp main to protect the generator to panel line.
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slim
Member
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# Posted: 27 Jan 2015 18:04
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I may be overthinking this thing. The generator itself has a 30 amp main breaker. I would plug into the 240 outlet at generator and run 20 foot cord to power inlet box mounted outside. Then run #10 wire to a ciruit breaker panel which would have have circuits protected by 15 and 20 amp single pole breakers, and maybe a 240 circuit protected by a 30 amp double pole. Maybe with the 30 amp main breaker on the generator itself, I would not need a main disconnect in the pole building. If I ever went ongrid, then meter and main breaker would be outside.
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MtnDon
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# Posted: 27 Jan 2015 18:33
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In that case you would only need a main breaker on the service panel if you wanted a disconnect located there. Being connected to the grid would change a few things, like needing a transfer switch if the generator was still to be connected for any reason.
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slim
Member
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# Posted: 27 Jan 2015 20:01
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Thanks MtnDon. For this temporary use, I don't really need a disconnect inside. I understand that if I am ever connected to a grid, things would change. A transfer switch would definitely be needed.
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toyota_mdt_tech
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# Posted: 28 Jan 2015 10:25
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Slim, the disconnect inside the cabin is nice. If you hear your generator running out of gas, you can quickly cut the power to prevent brownouts,(low line voltages/frequency, ie Hz)
Its nice to be able to disconnect the generator during startup or shut down this same way also. That would be the main reason. As for protecting the circuit from the generator to the cabin, you are right, the breakers in the generator will do that for you. So you could run is straight to the panel, but through a 30A double pole breaker would give you a nice disconnect. I would want to have a disconnect at both the generator and the inside panel myself. Its not as risky with an inverter type generator, but without the inverter type, I'd try to get disconnects at both ends.
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slim
Member
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# Posted: 28 Jan 2015 12:14
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Thanks toyota-mdt-tech. I definitely agree with you if I were powering a cabin. All I am doing is putting power to a pole building used to store a vehicle and tools. Just need some light (infrequently), and power for compressor, and hand power tools for occasionally working out there. Thanks for suggestions.
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