Power

[Dave Novak]

I ran the outlets, and used 30a outlets. I don't understand everyone's befuddlement with 30 amp. There are big boxes of 30amp outlets at Lowes. What's the reasoning behind the need for GFCI in my garage anyway? I usually only see these in bathrooms and kitchens near a sink. My garage is every bit as dry as my living room.

[Jim Becker]

What's the reasoning behind the need for GFCI in my garage anyway?

Grade level and potential for water from tires, etc. Further, many folks will use an outlet in a garage to run an outdoor power tool, like a trimmer. GFCI saves lives. Code is like that. Even if we don't understand it or agree with it, we must abide by it.

I'm still puzzled by the 30 amp 120v circuits. Very unusual...

[Dave Novak]

I plan to abide by code, I'm just trying to understand why things are the way they are. I hadn't thought about using garage outlets to power tools useds outdoors, that makes a lot of sence.

I guess part of my code skepticism comes from stories my Father has told me. I'm not stating this as a cold, hard fact, but my father has long told me that building codes aren't always only driven by safety concerns. The example he uses is that in Chicago/Cook county, plumbing code requires iron/steel pipes throughout the system, not just the supply side, but also the drain system. Years after the rest of the country had accepted PVC as a safe, economical alternative, Chicago plumbing unions have successfully lobbied against their acceptance because it takes fewer plumbers to complete a job using PVC.

[Brian Tuftee]

That's more of an issue with local codes and jurisdictions, instead of the national codes. The uniform national codes are, in my opinion, pretty free of that sort of thing.

[Bill Simmeth]

I myself am in a similar situation. My main panel is on the exterior wall to my garage.

John, if your shop is in the garage and your main panel is on the exterior wall of same, I'd think you'd be a perfect candidate for a sub-panel! I'd not use the cable on the existing 30A circuit. Sounds like you're quickly exceeding that capacity! Run a new cable (can't be a very long run?) to supply a 60A (or greater) sub. Re-route the existing garage circuits to the new sub and use their freed-up breaker space for the sub's breaker.

Good luck!

[J. Greg Jones]

Dave, the GFCIs are required for circuits in a garage. A power tool should not trip them, however, unless it's faulty. You may have a bad GFCI and they DO have a lifespan...unfortunately.

Jim, what about 240v in the garage-are GFCI breakers required there also?

[Dan Lyke]

On the nuisance trips bit: it becomes a safety issue if it happens often. Circuit breakers have a limited lifetime based on how often they trip.

This is going off-topic, but since the original question has been answered... My dad worked for a well known manufacturer of big circuit breakers for a while, and and one time when I was visiting I got to see a test of a breaker go wrong. This was more a "wing of a shopping mall" type breaker, but we were in the test lab, behind a foot of glass, with the admonition to "just in case" (because they didn't expect this one to fail) watch the monitors rather than the actual device because if it failed the arc would be really bright.

Yeah, breakers are hard to design because if they start to trip, pull the contacts apart, and there's an arc that melts the surface of the contacts, but the surge isn't high enough to complete the trip and they fall back together, then the contacts weld to each other. So if you have a trip that's two overloads in quick succession, the second trip can have the breaker trying to break against welded contacts, and the failure... uh... happens at other points in the system.

In the control room for the testing lab behind a blast wall and a foot of glass, this is really cool. In the real world, this is sub-optimal.

And it's this sort of thing that makes a breaker very different from a switch: Once the contacts pull apart at all they have to trip completely and very quickly, and a trip could result in pitting and flow in the contacts. And there are all sorts of other things, like soft failure (you want it to allow a little bit of overage for a longer time, to allow for short surges like motor starts or switching, but to trip instantly for other sorts of surges) that make breaker design a lot harder than you'd initially think.

[Brian Tuftee]

Under NEC 210.8, the section dealing with most GFCI applications, protection is required only for 120V single phase receptacles in 15A and 20A capacities. I think you can get 240V (double-pole) GFCI breakers, those would be used in hot tub and swimming pool applications. But for a garage, I don't think there's a GFCI requirement for a general purpose 240V receptacle.

[Greg Funk]

I'm still puzzled by the 30 amp 120v circuits. Very unusual...

They look like this...

[Pete Brown]

They look like this...

Greg, I've seen those too. However, it sounded to me like the OP had regular three prong duplex outlets on that 30A run. Either that or he put a new plug on all this tools

As an aside, GFCI isn't usually required on 240v because 240v outlets are typically single motor "dedicated" outlets that won't have you plugging in odd tools.

My shed does not have GFCI outlets inside (it has them outside). The inspector passed it but recommended that I put GFCI in there for safety. He said it wasn't strictly required by code but that he'd feel better if I did that in there.

Pete

[Tom Jones III]

Under NEC 210.8, the section dealing with most GFCI applications, ...But for a garage, I don't think there's a GFCI requirement for a general purpose 240V receptacle.

Sometimes local codes will require GFCI based on finished/unfinished applications and also if the garage is connected to the house.

[Brian Tuftee]

That was my confusion too, because you can't install regular duplex outlets (either the 15A or 20A variety) on a 30A circuit (well you can, physically, but it's not to code). Not sure what you'd plug into a NEMA 5-30R receptacle (the fancy name for what's in Greg's pic), I don't own anything that does. Maybe a welder?

[Jim Becker]

Greg, yes, that's what they look like...my confusion was to why they were installed as they are normally "special purpose" things and not common at all. Well, there is that one Grizzly saw that would need it for 120v use!

[Greg Funk]

Jim,

I suppose the receptacles are not very common but you can plug normal 15A appliances into them as well as the occasional heavier duty item.

While the receptacle I showed supports 30A plugs it's not clear to me why you couldn't put regular 15A receptacles on a 30A circuit. The circuit breaker provides protection for the wiring not the device plugged into it.

Greg

[Jim Becker]

Sorry, Greg...I don't know the code on this. But I'm one of those folks that likes to be consistent. If I have a 20 amp circuit with a 20 amp breaker, I also use 20 amp outlets. Oh, and I'm not sure how easily you could terminate #10 wire on a typical 15 amp receptacle...'could be maddening!