GFCI in the garage

[radhak]

In anticipation of the incoming Unisaw, I asked my electrician to put in a 240v outlet in my garage. Last year he had also put in a couple of additional 120v outlets, same area.

He works cheap, but I feel a bit too cheap : he did not put GFCI outlets - neither last time, nor this time. I asked him, and he tells me GFCI is needed only in places where there's a chance of water spills/leaks etc. But the one original outlet in the garage does have GFCI, so I am not comfortable with his reasoning.

Also, at times in the past, I have had the GFCI trip on me - mostly when I was running the shop-vac and the TS simultaneuously and was ripping red-oak. Is this something I need to worry about when running the Unisaw, and will a GFCI be justified just for that? It will be the only machine on that 240v circuit.

And while on that, I told him the saw is marked 18amps, but he insisted on putting in a 30amp breaker instead of a 20amp as I had expected. No skin off my nose, but just wondering if that's a good, cautious step, or an extravagantly cautious one.

[kbkreisler]

garage gfci

according to nec - national electric code- the garage is indeed an area in the home where a GFCI is required unless it is a dedicated receptacle. (i.e garage doors receptacles, or possibly the outlet for your new saw)
it is fairly inexpensive to put a gfci outlet in each 120v circuit and have the remaining outlets fed off the load side of the gfci receptacle. just make sure to get the 20A receptacles if it is a 20A circuit. With the electricians lack of knowledge of gfci code I would also check wire sizing,
12awg wire >= 20A breaker and receptacles
14awg wire >= 15A breaker and receptacles
I will state that the inconvenience of resetting a gfci trip is a much better option than a trip to the morgue... insist that the 120v receptacles are gfci protected.
Safety starts at home
kyle

[Uncle Cracker]

Your electrician did not misinform you. Many codes only require GFI in wet locations (where you might accidentally drop an appliance into a tub, sink, or toilet). GFI's in shops are sometimes problematic, because they really are not usually rated for much working power, although you could use a GFI breaker for your shop circuit. The usual caveat applies: When in doubt, check with your friendly local inspector, as interpretation and enforcement will vary.

[atgcpaul]

Are the new 120V outlets on a different circuit than your existing GFCI? If
he ran power from the existing GFCI circuit to the new outlets downstream,
then they are protected, too. I have 3 120V,20A circuits in my shop that feed
at least 2 outlets each downstream. On two of them, the first outlet is GFCI.
On the 3rd, the circuit breaker is GFCI. Why a mix? GFCI outlets cost more
than normal outlets--especially 20A ones--and I had an extra GFCI breaker
when I switched the garage from one GFCI breaker to a subpanel.

It's my understanding that GFCI isn't needed for 220V when there's no neutral
run-GFCI won't work without the neutral. This is the case with my 220
setup which is 2 hots and a ground. You should be OK.

I put a 220, 20A for my TS because that's what was suggested in the manual.
You should probably have your electrician switch yours. I don't quite
understand his logic when wiring your place. I can, though, if he was paying
for supplies and didn't want to pay extra for GFCI and had an extra 30A
breaker around.

Paul

[LarryG]

Pretty sure Kyle is correct about NEC requiring GFCI outlets in a garage. I can check this for you with our electrical engineering consultant.

I already know, from having asking him previously, that a 30A breaker is the correct size for an 18A motor. (I asked about a 17A load, and he said, "Thirty amps.")

[radhak]

This 240v outlet is on it's own circuit, as were the two 120v added last year. And this one has 2 hots (no neutral) - he showed that to me with his multi-meter.

He did have a 30amp breaker with him, but I think also 20amp ones and he reasoned it out to me that he did not want more than 80% of it's capacity to be hit any time, which'd make the 30amp a better choice.

But I gotta admit, he seems to have done better in his knowledge than I presumed at first - I see all his reasonings confirmed with all you're saying.

[LCHIEN]

I'm with uncle cracker on all his statements above.
For a shock hazard to exist and the GFCI to work there has to be an alternate path for the electricty to return to ground other than thru the neutral. I virtually all cases I can think of, only a water soaked or wet floor or other wet-to grounded piping contact area is needed. A DRY garage will not trip a GFCI unless you are physically in contact with a grounded object and you come in contact with the hot side of the line due to an insulation failure. I do suppose one instance of this is where you are leaning against the steel table saw, its grounded and simultaneously using a corded tool which has a hot insulation failure to your body...

[dbhost]

We all know building codes vary per region, but a garage is a MUST HAVE area for GFCI protection. Concrete is a great conductor.

[crokett]

Around here it is GFCI in wet locations (bathrooms, kitchens, etc). Garages/shops are not strictly needed. That said, when I took power out to the shed I hooked it in to one of my 20A shop circuits. I replaced the last outlet before the load goes outside with a GFCI. I figured better safe than sorry.

[LCHIEN]

We all know building codes vary per region, but a garage is a MUST HAVE area for GFCI protection. Concrete is a great conductor.

Hardly, Concrete is a lousy conductor. there are some guys trying to develop conductive concrete, but its a real chore; they call normal concrete an good insulator:

Conductive concrete is a cement-based composite that contains a certain amount of electronically conductive components to attain stable and relatively high conductivity. In essence, the aggregates normally used in concrete can be largely replaced by a variety of carbon-based materials to achieve electrical conductivity in conductive concrete. This is achieved while retaining the desired engineering properties, as indicated in Table 1. The conductivity is usually several orders of magnitude higher than that of normal concrete. Normal concrete is effectively an insulator in the dry state, and has unstable and significantly greater resistivity characteristics than conductive concrete, even when wet.

If it has more than a few-thousand ohms (to ground), then it will protect you, it doesn't have to have multi-megaohms to keep you from getting shocked.

[LarryG]

As promised, I ran these questions by our electrical engineering consultant.

While I was waiting for him to reply, I found this summary chart of required GFCI protection locations on the web. Unfortunately, it is only current through 2002; but as can be seen, garages and areas or outbuildings used as shops are required to have GFCI protection at all 120V outlets, with only a few exceptions. Our engineer tells me that in the 2008 edition of the NEC, the exceptions for garages have been removed; i.e., ALL garage outlets must be GFCI.

But as UC mentions, it will depend on what version of the code your area has adopted. However, note that the garage requirements began in 1978. So there's virtually no chance that any circuit intended for tool use that was installed within the last 30 years can be code-legal if it's not protected.

On the matter of 240V circuits, he says that he's never seen any GFCI receptacles other than 120V, 15A and 20A; but that it is possible to have GFCI protection on a 240V circuit at the breaker. The devices work by sensing an unbalance between the two conductors (hot/neutral for a 120V circuit, hot/hot for a 240V circuit). However, the 240V GFCI breaker is apparently only required for wet locations like swimming pools and fountains, and would not be required for a 240V circuit in a shop, even when the shop is located in a garage.

Finally, on the 30A breaker question, he wrote: "That sounds right in most cases. (Note: he knows that the questions I ask him are always in the context of a home workshop.) However, if this was a commercial project, I use a Square D slide chart for motors/breakers and it shows a 35 amp circuit breaker for a 3 HP, 17 amp motor. My Cutler-Hammer slide chart shows a 40 amp circuit breaker for a 3 HP, 17 amp motor. The intent is to have the lowest rated circuit breaker that will not accidentally trip at motor start-up."

[radhak]

Thanks Larry for the trouble you took for that information; that goes for everybody else too of course. More than the answer, such a discussion really opens up a lot of unknown areas for me.

I shall leave the 240 one out for now, but ask him to change the 120v to a GFCI one.

[poolhound]

I added new dedicated wiring in my shop/garage earlier this year. The exisiting 15A circuit is GFCI protected. According to a lengthy discussion with my electrical contractor it would seem that It is required for a garage installation, however there is an exception. If you are only ever attaching one thing to the outlet you do not need GFCI.

I decided to not put GFCI recepticles (8 of them) in. If I need to protect the circuits at some stage for example when I sell the house, I can install GFCU breakers or even just protect the main breaker in the panel.

[Tom Slick]

Just as general info for everyone, NEC codes are the basis used by almost every municipality and local codes are only added onto it, not taken away. There are very very few areas that don't use the NEC, usually because they have their own. I believe NYC and Chicago don't use the NEC.

what I'm getting at is when the latest NEC is stated, you can bet that it is minimum code for your area.

Technically, when adding a new circuit to your garage it needs to be done to the latest NEC, regardless of what the existing wiring is.

[tfischer]

As noted above, with few exceptions, GFCI's have been required in garages and unfinished basements since 1978...

-Tim