arc fault circuit breakers

[brenthenze]

All,

I'm in the midst of wiring my new shop, and I wonder if anyone has had either good or bad experiences using arc fault circuit breakers. I don't think that they're required in my application, but I'd thought about using them for the added measure of safety. However, somewhere I read that contractors didn't like them because they routinely tripped when miter saws and the like were used with them. Obviously, that'd be a frustrating thing in a woodworking shop!

What's the collective wisdom as to whether to use arc fault circuit breakers (or GFCI's, or just plain old vanilla breakers) in a new woodworking shop?

TYIA, and happy new year,

Brent

 

[NZAPP1]

I would not use them in a shop they will trip out when you use tools with brushes like Miter saw corded drills router and so on because the brushes arc.

 

[FredP]

when I wired my shop I was under the impression that they were required. when the inspector showed up he imformed me 5they were not. at least not all of them. he said the ones that were at standard hieght [low] and near the doors needed to be but the ones above work benches need not be GFI. I changed the GFI breakers out for standard breakers when they started tripping all the time. I used GFI outlets near the door only. Basically he said if the outlet could be reasonably assured of using for outdoor use such as weedeaters or christmas lights ect.... they needed to be GFI. outlets over work benches are concidered dedicated and did not have to be GFI. that may be just my inspectors oppinion.:icon_scra he said the NEC was a bit vague on the subject.:dontknow: your best option would be to check with your county inspector to see what he wants you to do.

 

[RayH]

Brent,

I'm sure Fred has the best answer -- check with your local building inspector.

One additional thought -- even if you wire a circuit non-GFCI, you can later install GFCI outlets that will protect themselves and can be wired to protect all other outlets downstream on that circuit.

Best of luck,
Ray

 

[Glennbear]

I agree that AFI's are not a good choice for shop use with the arcing inherent in some of our machines. After wading through the NEC and consultation with the county inspector (ironically his background is in the electrical trades) , I equipped my shop with GFI's wherever possible including some instances where they are not required such as the ceiling outlet for the overhead door opener. My rationale for this unmandated protection is that the electronics in the opener mechanism might be better isolated from surges etc. :wsmile: I did find a fantastic reference book written by a local electrician who believes in wiring "above code" when it makes sense to do so: "Wiring a House" by Rex Cauldwell available from Taunton Press. As opposed to a book written by a "desk jockey" or "code enforcer" Rex is a practicing electrician with over 3 decades of experience in NC and VA.

 

[ultgar]

ARC fault - Definitely not for use in the workshop. Do all of your 110v wiring with 12 gauge and 20a breakers. Plenty of dedicated circuits. If you need GFCI protection, consider a GFCI breaker instead of feeding multiple receptacles though a GFCI outlet. Consider using industrial grade or hospital grade receptacles...I like Pass & Seymour and Hubbell devices.

A few 220v (20 or 30a) circuits with 10 gauge wire. Lighting can be done on 15 amp (14 gauge) circuits. SD

 

[Glennbear]

ARC fault - Definitely not for use in the workshop. Do all of your 110v wiring with 12 gauge and 20a breakers. Plenty of dedicated circuits. If you need GFCI protection, consider a GFCI breaker instead of feeding multiple receptacles though a GFCI outlet. Consider using industrial grade or hospital grade receptacles...I like Pass & Seymour and Hubbell devices.

A few 220v (20 or 30a) circuits with 10 gauge wire. Lighting can be done on 15 amp (14 gauge) circuits. SD

Steve has some sage advice however I would stick with 20A breakers and 12 GA wiring for all circuits since it makes for greater choices when the inevitable future add-ons pop up. I stuck with GFCI outlets instead of breakers since the breakers were obscenely expensive however YMMV. :wsmile:

 

[FredP]

hurrah on the 12 guage wire! I never use 14 guage for anything. :nah:

 

[McRabbet]

I must humbly disagree with Glenn and Fred on the exclusive use of 12 gauge wire for all of the 120V circuits. While I agree that all outlets should be wired with 20 Amp breakers, 12 gauge wire and 20 Amp receptacles, I have always used 14 gauge wire for my lighting circuits (14/2 for single switch circuits and 14/3 for 3-way switched circuits) and keep the load to less than 10 amps per lighting circuit. I also never mix receptacles and lights. My 230 Volt circuits are dedicated 20 Amp and 30 Amp and are run with 10 gauge wire. I have one bench receptacle circuit that runs within 5 feet of a future sink, so it is uses a GFCI receptacle with labeled standard receptacles slaved down run. In total, I put 2 lighting, 4-120V receptacle and 3-230V dedicated machine circuits in my shop.

 

[Travis Porter]

Keeping the lights and receptacles separate makes sense, and is what I did. The NEC says you can go to 80 percent of load so 12 amps would be more realistic (and cheaper) than 10 amps on a 15 amp circuit for lighting.

As for GFCI, I would recommend using them on any receptacle that can be used near water. That would be all outside receptacles and all receptacles near a sink.

Personally, I made all of my shop receptacles 20 amp with 12 gauge wiring, but it was not cheap. you can buy 15 amp receptacles for dirt cheap, but going to 20 amp receptacles was about 4 times as expensive. 20 amp receptacles are nice to have, but I currently only have 1 tool that has a 20 amp plug. Price of copper has come down so it is easier to do now than regret doing later....

As for GFCI, I too went with the receptacles and not the breakers as the breakers were very expensive. Addtionally, I made all my GFCI circuits/receptacles 15 amp as the 20 amp GFCI receptacles were obscenely expensive.

To date, and it has been 6 years, I have not tripped a single 110V circuit. Conversely, I have tripped several 220 volt 20 amp, 30 amp, and 40 amp circuits.:eusa_doh:

 

[cpowell]

I don't see how they (AFCI bkrs) would be beneficial in a detached shop environment.

My detached shop only has a few GFCI receptacles. I used them where It is possible I could plug in drop cords to feed outside power needs.

Short answer - if they are a NEC requirement then you should use them. My experience with the NEC is that it errs on the side of caution - ALWAYS. If you follow the code you shouldn't have a problem.


Chuck

 

[Glennbear]

Steve has some sage advice however I would stick with 20A breakers and 12 GA wiring for all circuits since it makes for greater choices when the inevitable future add-ons pop up. I stuck with GFCI outlets instead of breakers since the breakers were obscenely expensive however YMMV. :wsmile:

Keeping the lights and receptacles separate makes sense, and is what I did. The NEC says you can go to 80 percent of load so 12 amps would be more realistic (and cheaper) than 10 amps on a 15 amp circuit for lighting.

As for GFCI, I would recommend using them on any receptacle that can be used near water. That would be all outside receptacles and all receptacles near a sink.

Personally, I made all of my shop receptacles 20 amp with 12 gauge wiring, but it was not cheap. you can buy 15 amp receptacles for dirt cheap, but going to 20 amp receptacles was about 4 times as expensive. 20 amp receptacles are nice to have, but I currently only have 1 tool that has a 20 amp plug. Price of copper has come down so it is easier to do now than regret doing later....

As for GFCI, I too went with the receptacles and not the breakers as the breakers were very expensive. Addtionally, I made all my GFCI circuits/receptacles 15 amp as the 20 amp GFCI receptacles were obscenely expensive.

To date, and it has been 6 years, I have not tripped a single 110V circuit. Conversely, I have tripped several 220 volt 20 amp, 30 amp, and 40 amp circuits.:eusa_doh:

The moderators must be getting soft, they are letting all this obscenity slip by :rotflm:

 

[Gofor]

Just to avoid some confusion that may be had from reading the above: Arc Fault and Ground Fault are not the same thing.

Ground Fault protection should be used in any area where there is a possibility of moisture or spilled water enhancing you of being grounded [i.e. if your garage floods when it rains, or if the concrete floor sweats in humid weather, your should have GFCI (Ground-Fault Circuit Interrupter) protection. Also, all bathroom outlets, those near sinks, crawl-spaces under house, and outdoor outlets]. Right now, AFCI (Arc-Fault Circuit Interrupter) protection is only required on 120v bedroom outlet circuits. There was talk of the new NEC requiring it on all household circuits. However, last I heard was the NC electric codes may exempt this provision, (as they did for GFCI on sump-pump circuits) as it is getting a lot of resistance from the construction industry. I haven't seen the new NEC yet.

The difference is that GCFI protects you from being electrocuted, and the AFCI protects your house from catching fire from an arcing connection.

Go

 

[brenthenze]

Thanks for all of this excellent advice. I'll forego the AFCIs (your comments confirm what I'd read somewhere before: that saws and other brush-type motors can needlessly trip AFCIs), since the local code doesn't require them. My shop doesn't have plumbing, so the only places where GFCIs are required, I guess, is the exterior receptacles and the one right by the door. But it's simple enough to add a gfci receptacle at the start of each run, so I might just do that to be safe.

I'd already planned to use all heavy-duty 20amp 110v receptacles (and I already bought them), but I guess I'll need to get one 20amp GFCI receptacle for the start of each run. I've also already pulled all my cable (all 12awg for the 110v runs, though I admit that I only used 14awg for one loop of ceiling lighting--I had the cable handy).

My circuits, altogether, are:

220v circuits: five 220V (using 10awg cable) outlets, each on a separate circuit; one one each wall, plus an additional one on my longest wall.

lighting circuits: one 110v (14awg) circuit in the ceiling. I'd planned to install eight or ten flourescent fixtures (2x4') on chains, all on one switch; it's one big rectangular room. There'll be additional plug-in task-lighting here and there.

110v receptacle circuits: each of the two long walls has two circuits on one cable (12-3 cable, and I'll split it to get two independent circuits). I'm using two-gang boxes throughout, so I'll have four outlets at each spot along the wall; in each spot, the left side will be one circuit, the right side another. There's also a separate circuit (with just one duplex receptacle) on the short wall with the garage door.

Upstairs--uninsulated, mainly for lumber storage--there'll be one lighting circuit (12awg this time so that I can use the fixtures as receptacles in a pinch) as well as a couple 110v receptacles on the end wall (12awg also) on a second circuit).

Outside power: two 110v GFCI circuits (with three receptacles altogether, in waterproof boxes): two on the wall with the open shed, plus one more on the opposite side of the building.

 

[Travis Porter]

One further suggestion. I suspect you are going to sheath your walls so get you a 1 1/2" or 2" piece of conduit and run it up the wall into your attic from the fuse panel. You will be amazed once you have all that space how quickly you will fill it up and need additional 220V outlets that you never planned on needing. DAMHIKT