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I've purchased a portable generator that I'm planning to use in case of an outage. I'm not wanting to wire this to my house wiring; I'm just planning to install an outdoor inlet wired to a dedicated outlet in the house, and connect a power strip to some items during an outage. What do I need to be aware of in this kind of setup? Do I need to install a separate ground line for this outlet? Would I be violating any kind of code with this install? Any help would be appreciated. Thanks.

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    Will you be using 20, 30, or 50 ampere output from the generator? – Tester101 Jan 4 '16 at 11:27
  • The output from the generator is rated for 20 amps. I'm thinking primarily connecting some small electronics like a laptop and cell phones, and possibly a small portable A/C unit in the summer. – Sal74 Jan 5 '16 at 5:50
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If you want this to look decent, and be safe. You want to have something like this:

20 ampere generator hook up

Circuit Protection

This setup assumes that the generator provides overcurrent, short-circuit, overload, and ground-fault protection. Likely via a circuit breaker, and a GFCI receptacle. If this is not the case, you'll want to provide that protection within your wiring.

If the generator output does not have short-circuit, overcurrent, and overload protection, you'll want to install a circuit breaker somewhere (likely between the inlet and the receptacle). If the generator does not provide ground-fault protection, you'll want to have that somewhere as well (likely via GFCI receptacle, or GFCI circuit breaker).

Shock Hazard Protection

You'll notice in the above diagram, that an inlet is used, and that the female end of the gen. cord plugs into the inlet. To understand why this is important, let's take this example.

The power goes out. You go out and start up the generator. You plug one end of a double male ended cord into the generator, and drag the other end over to the "input receptacle". As you do so, you touch the exposed prongs at the end of the cord. ZAP! You dead.

If the generator does not accept a male plug connection, you'll want to make up a double female cord. That way you'll plug a female end into the generator, and a female end into the inlet. You don't ever want to have exposed energized parts, as they are a serious shock hazard.

Sizing

Make sure all wiring and devices are sized properly. If you're working with a 20 ampere 125 volt output from the generator. That would mean 20 ampere devices, and at least 12 AWG copper wires.

Grounding

As this setup is basically an extension cord, there's no need to bond it to the electrical system of the house. The neutral-ground bond on the generator should be left in place.

NEC 702.11 says that the generator has to be grounded to a grounding electrode in accordance with 250.30.

Signage

According to NEC 702.7(C), there should sign near the inlet that reads:

WARNING:
FOR CONNECTION OF A SEPARATELY DERIVED (BONDED NEUTRAL) SYSTEM ONLY

  • how does grounding work in a standby generator situation like this? Should the generator be bonded to the home ground? If no, is it a problem if the bare ground wire accidentally touches a house ground (like a pipe or metal junction box)? Should the neutral-ground bonding strap (present on many contractor style generators for OSHA compliance) be present or removed? – Johnny Jan 5 '16 at 18:38
  • I'm not sure if a setup like this is to code, but it should be as safe as running an extension cord through a window. – Tester101 Jan 5 '16 at 18:47
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    @Johnny -- the neutral-ground bonding strap should be present as this is a "separately derived system" in the NEC -- the generator also needs a grounding electrode driven for it. The only time you remove the bonding strap is when you are installing the generator as something other than a "separately derived system" by transferring only the hots of a circuit or circuit(s) to the generator. – ThreePhaseEel Jan 6 '16 at 12:46
  • @Tester101 -- what you have here is almost right -- there are a couple of caveats related to labeling in Art. 702 of the NEC involved though. – ThreePhaseEel Jan 6 '16 at 12:48

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