Power

[Dave Novak]

First off let me thank all of you for providing me countless hours of informative enjoyable reading. I only recently stumbled into this website and I'm addicted. My boss hates you.

I'm really not much of an electrician, so any help you guys can offer would be very much appreciated. I recently bought a Laguna LT16HD bandsaw. I only have 1 220v circuit in my house, it's 30 amp (at least that's what it says on the breaker) and it's running to the laundry room. Lucky for me, my garage shop shares a wall with the laundry room. I tapped into it to add a 220v outlet in the garage. I assumed I could splice into the wire I ran across the garage attic to add more outlets as necessary.

My next purchase is going to be a Dust collector (reading these forums has me convinced I need an Onida and a second job) and most of the better units also require 220v. My initial reaction was no problem, I'll just run another outlet into the garage. But will I be able to run both my bandsaw and a DC at the same time on the same circuit? What if the wife happens to be using the dryer? Will i be able to run either unit? Thanks in advance for your thoughts!

[Jim Becker]

Dave, it's not really kosher to "spice into" your dryer circuit. Not only can you not run your tool(s) when the dryer is in operation, you may have a problem with code.

You really should have two 240v circuits (minimum) added to your shop...one for the DC and one for the tool being used. The Oneida and other similar machines should be on their own circuit, IMHO. My suggestion is to have a sub-panel brought into your shop for tool circuits. Talk with a licensed electrician about that to be sure you can do that with your present service and to find out the cost.

[Brian Tuftee]

What are the nameplate amperage draws on your DC, bandsaw, etc. Is the dryer electric or gas? Add up all of the loads, if you're close to 30A, you'll probably see nusiance tripping on that circuit. If you have open space in your breaker box, why not just run a feeder to a 60A subpanel in your garage? That's what I'd do, instead of leeching power from other circuits in your house - you'll have enough power that you'll never worry about it again.

Also, I think under the NEC that a laundry circuit 'technically' needs to be dedicated, i.e. share no other outlets or receptacles in other rooms, but I'd have to pull up the code and double check that.

*edit* Yep, you're not supposed to splice into a dedicated laundry circuit. NEC 2005, 210.11. Just do a subpanel instead.

[Dave Novak]

That's what I was afraid of. I'll probobly just hold off on dust collection for a while. I need a little time to financially recouperate from the saw purchase, and having electricians over for a wiring party would surely sink me. Thanks for the quick response!

[Brian Tuftee]

You may want to check out this article at Hammerzone.com, on installing a subpanel. The hardest part of this job is actually fishing the wire from the main panel to your garage. If you can manage that, the rest is easy.

http://www.hammerzone.com/archives/elect/panel/sub_panel/01/overview.htm

Once you have the subpanel in your garage, you can install dedicated 240V and 120V circuits for your equipment, and never worry about tripping a breaker.

[Dave Novak]

I believe you, but it doesn't really make sense that you can't splice into an existing circuit to add another outlet. There's only one outlet on that circuit now, and it's only used when the dryer is running. Everywhere else in the house there are many outlets and maybe even lighting on single circuits. As long as the total amps running at one time are below 30 or what ever the breaker limit is, it would seems to be ok. I know the code says otherwise, I'm just wondering if the code isn't at least partially designed to keep electricians employed.

[Dave Novak]

Thanks for the link to the artical. Before I finished off my basement I had electricians run three additianal 30 amp 110v circuits to the garage. At the time I didn't envision ever requiring 220v. What an idiot I feel like now, as that was only 4 years ago, and with the basement finished running wires from the brewaker box to the garage would be quite a chore.

[Brian Tuftee]

Nah, the code is there just because most people would burn their house down in ten minutes, if given free reign over their electrical systems. Ok, that's an exaggeration, but electricity (unlike, say, plumbing), is life or death - no one ever got killed from a leaky toilet.

In some cases, code requirements can be a little hard to understand. In cases with dedicated branch circuits (laundry, bathroom, and kitchen small-appliance circuits), I suppose the rationale is to avoid nuisance trips. Not a straightfoward safety issue. I agree that if the branch circuit wiring is properly sized, with the appropriate breaker, there should be no safety difference than any other circuit in the house.

Total cost of materials to do this is pretty low, I'd guesstimate around a hundred bucks (depends a lot on the length of cable you need). If you feel comfortable with installing outlets and whatnot, you might want to give this a try. Pull a permit, get a book or two, ask questions in here, and you'll almost certainly pass inspection.

[Pete Brown]

I believe you, but it doesn't really make sense that you can't splice into an existing circuit to add another outlet. There's only one outlet on that circuit now, and it's only used when the dryer is running. Everywhere else in the house there are many outlets and maybe even lighting on single circuits. As long as the total amps running at one time are below 30 or what ever the breaker limit is, it would seems to be ok. I know the code says otherwise, I'm just wondering if the code isn't at least partially designed to keep electricians employed.

No. Major appliances - stoves, dryers, AC, etc. all need dedicated circuits. In fact, even your Microwave should have a dedicated circuit, as it has become a fixed appliance in most homes. You should never go above 80% load for a circuit, IIRC, as most motors spike on startup.

If you run your 240v saw while someone runs the dryer, you may be screwed. Do you have a magnetic starter on your saw? If not, you'll need to remember to turn if off or else you'll have a real mess when you power back up.

How did you "splice in" to the circuit? Is the wiring all sized appropriately and did you do everything inside an appropriate wiring box?

If you go to sell your house, you will have problems with the inspection. If you have a fire right now, you will have problems with insurance. I suggest following Jim's advice and breaking out a subpanel for the garage and running the wiring back to your main panel. Nuke the splice.

There are a lot of things I'll mess with in my house. Electricity isn't one of them. If you're going to do that in your house, make sure you get some good books on the subject so you can do your best to do it correctly.

Pete

[Pete Brown]

Nah, the code is there just because most people would burn their house down in ten minutes, if given free reign over their electrical systems. Ok, that's an exaggeration, but electricity (unlike, say, plumbing), is life or death - no one ever got killed from a leaky toilet.

I don't know about that. You should have been here when they pumped the septic right after we moved in. The toilet downstairs "burped" and I thought for sure I'd pass out ;)

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. That's why (unless rated to do so), they can't be used as regular switches. They will eventually fail if they trip too many times. I have no idea how many that is - it is likely more than any of us will ever run into, but it is still a possiblity.

Pete

[Rod Sheridan]

Hi Dave, as long as the 30 Ampere, 120 volt circuit isn't used for anything else, you can convert it to 240 volt by replacing the single pole 30 A breaker with a 2 pole (I'd go with 20A) and use it for your dust collector.

The #10 wire is oversized, however that's a good thing.

You could convert the other 30A circuit to 240 V for all your 240 volt tools and still have one remaining 30 Ampere 120 volt circuit for other stuff.

P.S. the code requirement for nothing else on a dryer circuit is due to demand loading limits on the circuit. The electrical code gets updated on a scheduled basis, many of the updates are due to fires or fatalities in the past. Not following code is illegal, and just plain iresponsible.

Regards, Rod.

[Justin McCurdy]

I just went through this a couple of weeks ago. I had no 240 in the garage, a laundry room with a shared wall to the garage, and only 1 space( instead of the necessary 2) left in the main house panel. After much debate, I ended up with a sub-panel in the garage. I don't know what length of wire you need, but here were my costs:

Panel: $38 ( 16 breaker Siemens )
Main Wire: 125 ft. of 10 -3 (which is 3 conductor and a ground) for around $130. I only needed 10-2 but I listened to the guy at Home Depot, now I want to kick myself.
Extension Wire: 30 ft. of 10-3 wire (this time, because it is SJOO or SOO, the ground is part of the wiring designation) $50
Breakers: $8 each

So, for under $250, I was able to power anything I could ever want in my garage (that is not 3 phase).


Figure that $250 vs. the cost of accidentally ruining a motor or causing a house fire and it is a no-brainer. Sometimes it is better to bite the bullet than cause yourself more worries in the end.

//------------------------------------------------------

On the other side, if you are absolutely positive that you will only need a couple 240 outlets in the garage, buy a couple 1/2 space breakers and put them in your main panel. If you buy enough of these ($15), you should be able to free up enough room for a double pole breaker.

My 2 cents.

Justin

[Pete Brown]

Hi Dave, as long as the 30 Ampere, 120 volt circuit isn't used for anything else, you can convert it to 240 volt by replacing the single pole 30 A breaker with a 2 pole (I'd go with 20A) and use it for your dust collector.

You'd need to also mark the neutral (white) wire with black or red tape to indicate that it is hot. I don't recall the code requirement here, but it is one of those colors. Do that at both ends, and make sure you have the formerly-neutral wire connected to the circuit breaker and not to neutral in the panel.

Pete

[Brian Tuftee]

I take it back, re-identifying the white conductor as a hot wire would be acceptable here, so long as it's done in a permanent manner, and at each point where the conductor is visible or accessible, including the two terminated ends. Normally, black and red are the two colors of choice for hot conductors in a 240V circuit.

*gotta read the NEC closely...*

This would allow a much easier creation of a 240V circuit to the garage, though he'll still need space in the breaker panel to do it.

[Pete Brown]

On the other side, if you are absolutely positive that you will only need a couple 240 outlets in the garage, buy a couple 1/2 space breakers and put them in your main panel. If you buy enough of these ($15), you should be able to free up enough room for a double pole breaker.


Just make sure the panel 1. allows for the half-space breakers and 2. doing this doesn't go over the limit for the panel.

There are lots of places to screw up when you mess with wiring :)

In my county in MD, homeowners are not allowed to do any wiring themselves. If you did some and there's a problem with your house after you sell it, the new owners can still sue you.

Pete

[Pete Brown]

Problem is, he'd still have to run another wire for each circuit to make that work. The existing 30A, 120V circuits to the garage would only have one hot conductor. If he's going to go running wire, he might as well drop in the subpanel.

240v is two hots and a ground. you can use the neutral as a hot if appropriately marked. Most codes allow for that, IIRC. You just have to make sure it is marked on both ends and terminated properly in the panel.

Pete <-- not an electrician. Don't take my word for code.

[Richard Kee]

Dave,

The NEC is part of the National Fire Protection Association of publications specifying MINIMUM requirements for the safety of the general public. Advice from those already posting, and from me, is not to shortchange these requirements.

Now, I want to commend you for your selection of the 30A 120V service that you've already installed in your garage. It EXCEEDS NEC requirements, and that's great. Seldom will you ever approach the capacity of these circuits, and an added bonus is that the increased wire size for 30A service is much larger, resulting in less voltage drop across the wire, and delivering more power to tool in use. Additionally, over a few years use, the extra cost for the increased wire size will be paid for by the decreased power loss in the wiring (Larger wire requires less power).

You've already received valuable advice from previous posters, so I need no repeat it. Be patient, and do it right the first time - then enjoy the tools for the purpose you purchased them, knowwing that you're operating safely from the power supply viewpoint.

Richard J. Kee
Registered Professional Engineer
State of Ohio

[Jim Becker]

The 120v circuits that were added to his space already are likely 20amp, not 30amp...that may have been a mis-print. 30amp 120v is REALLY rare...

[Brian Tuftee]

240v is two hots and a ground. you can use the neutral as a hot if appropriately marked. Most codes allow for that, IIRC. You just have to make sure it is marked on both ends and terminated properly in the panel.

Pete <-- not an electrician. Don't take my word for code.

Yep, caught my mistake right after I posted my message. I fixed my original post. Been awhile since I scoured the NEC...

[Dave Novak]

I'm not worried about the cost. I just spent $3000 on a saw, another couple hundred to ensure it works is a no-brainer. The proble is ripping through all the drywall necessary to get power to a new garage panel.

Of the three 30 amp 100v circuits I had already run to the garage, only one is left. One went to about 20 spotlights in the celine and the other to 16 new outlets (I know that sounds like a lot of outlets, but I can only use one at a time so It can't hurt, can it?). The last circuit, which I believe is just a black and white wire can't be enough to supply a sub-panel, can it?

[Dave Novak]

The 120v circuits that were added to his space already are likely 20amp, not 30amp...that may have been a mis-print. 30amp 120v is REALLY rare...

No, I'm sure they're 30 amp.

[Richard Kee]

REALLY!

I can cite a number of cases where safety-conscious individuals have installed circuits that EXCEED NEC requirements simply for the fact that over their lifecycle, they save the person installing the circuits money due to decreases in power loss in the circuit.

Richard J. Kee

[Brian Tuftee]

You can get subpanels in a range of sizes, it really depends on what's feeding it. The better question is whether that 30A branch circuit is enough to supply your 240V equipment (assuming you converted it to 240V). That would require looking at the current draws for the equipment you plan to hook up to it. For this application, I probably wouldn't run a subpanel, just convert the circuit to 240V, then run an additional outlet or two off of it.

30A 120V is odd though, since all of the receptacles connected to it would have to be rated for 30A (and those would be 'odd' configurations, not the 'normal' duplex outlets we're used to). On a 20A circuit, you can use standard duplex receptacles rated for either 15A or 20A. Not saying that it's not what he has, it's just strange. If the breaker says 30A, and it was installed by a pro, then that's what it is.

[John Hulett]

I myself am in a similar situation. My main panel is on the exterior wall to my garage. Two years ago, I ran two 20A 120v circuits into my garage. Last year, I bought a MM16 that required the 30A 240v circuit, but there was not enough space for a two-pole breaker left on my panel - I only had one space left.

An electrician friend came over and brought with him a 2-pole quad breaker; the two inner circuits are bridged for the 30A/240v, the the two outer circuits are 20A/120v. Looks sorta like this (http://www.lowes.com/lowes/lkn?action=productDetail&productId=71588-1318-MP23020&lpage=none). That worked well - I accomplished my goal and still ended up with a spare breaker space. Until now...

Last weekend, I picked up a big compressor that requires 220v, and I'm looking at a cabinet saw next year, which effectively means more 240v circuits in my garage. I recalled seeing an article in a past issue of Popular Woodworking (http://www.popularwoodworking.com/store/backissue.asp?issuedate=10/1/2005)entitled Efficient Shop Wiring. The article describes how to utilize a single 240v circuit to run both 240v and 120v circuits to your shop on the same cable run. I considered doing this, but after researching further, I'm looking at a sub-panel now. I may just end up utilzing the existing 30A circuit to supply power to the sub... not sure yet. One thing I think I've figured out is I know I want to plan for at least 2 more future 240v circuits in addition to what I need today... maybe 3.

[Dave Novak]

Isn't the standard wiring builders have been putting into garages lately pathetic? Mine's pretty big, about 970 sf, and I think it came with 4 20 amp outlets, at least one of which (and maybe all) was on a GFI circuit. A decent sized framing saw would trip that if it bound up a bit.

After listening to you guys I'm calling in an electrician. Maybe I can find a friend of a friend who will help me out in his spare time at a reduced rate. I think most of this work is close to common sense, but I just don't know all the possibilities (like quad breakers) and I don't have a month or more to study up on it. One of these days I'll have to stop reading these forums and actually do my job.

[Jim Becker]

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.

[Dave Novak]

Thanks Jim. I may have big problems selling this house, as none of the outlets on the 30 amp circuit I ran are GFCI.

[Pete Brown]

Thanks Jim. I may have big problems selling this house, as none of the outlets on the 30 amp circuit I ran are GFCI.

Dave, since a 30amp GFCI outlet may be hard to find (and you need to wire them correctly with the GFCI outlet protecting the remaining outlets), you may want to get a GFCI breaker instead. Ask your electrician about one. They're pricy, but save dealing with the outlets.

Pete

[Dave Novak]

Thanks Pete, more evidence that I need an electrician.

[Brian Tuftee]

Thanks Jim. I may have big problems selling this house, as none of the outlets on the 30 amp circuit I ran are GFCI.

This worrys me more, because that's definately not code compliant. The electrician you had do this screwed up, especially if he ran standard 15A or 20A receptacles on this 30A circuit (also a violation). You'll probably have to get it fixed before you can sell. You don't run 30A on general-purpose receptacle circuits.

[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... :rolleyes: 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. :eek:

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!

[Pete Brown]

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

Among other things, wire size. Most 15A or even 20A duplex receptacles are not sized to handle the larger incoming and outgoing wires. The wiring box can also get pretty tight. This is more of an issue if you use GFCI outlets, which may be why no GFCI outlets were in use in there.

More importantly, if that wire has 30A going through it due to being at or near capacity, all the upstream outlets (between you and the breaker box, as they are chained) must be able to survive 30A of current. A 15A outlet is rated to only handle 15A. Outlet go boom.

Pete

[Pete Brown]

Found this:

NEC Table 210.21(B)(3)
Circuit rating (amperes) Receptacle rating (amperes)
15 not over 15
20 15 or 20
30 30
40 40 or 50
50 50

[paul aubin]

On the 30 amp 120 circuits unless you are the original owner of the house check the wire size feeding the garage. Do not rely on the breaker size, it is possible that a previous owner installed a larger breaker due to nuisance tripping or other needs but the wire in the wall is not #10 or better.

As for GFCI requirement All general purpose outlets in unfinished basement and garages are required to be GFCI. Dedicated outlets such as those for a freezer, Dust collector, Sump pump do not have that requirement. You can buy double pole GFCI breakers $$$$$ but they are not required for dedicated uses.

/paul

[Pete Brown]

As for GFCI requirement All general purpose outlets in unfinished basement and garages are required to be GFCI. Dedicated outlets such as those for a freezer, Dust collector, Sump pump do not have that requirement. You can buy double pole GFCI breakers $$$$$ but they are not required for dedicated uses.
/paul

Also keep in mind that being GFCI protected does not mean you need a GFCI outlet in each box. You only need one on each circuit.

Pete

[Greg Funk]

More importantly, if that wire has 30A going through it due to being at or near capacity, all the upstream outlets (between you and the breaker box, as they are chained) must be able to survive 30A of current. A 15A outlet is rated to only handle 15A. Outlet go boom.
Pete

I don't really understand what you are saying here. Why would the load be running through an upstream outlet? I suppose if you were using the receptacle to tie the wires together rather than a using a mar connector? I am not an electrician so I don't know if that is proper. In any case I wouldn't do this and I am not recommending it for anyone else.

I think this discusssion is somewhat interesting but not really germane to the topic so I will bow out now...

Greg

[Brian Tuftee]

As for GFCI requirement All general purpose outlets in unfinished basement and garages are required to be GFCI. Dedicated outlets such as those for a freezer, Dust collector, Sump pump do not have that requirement. You can buy double pole GFCI breakers $$$$$ but they are not required for dedicated uses.

/paul

Only if they're 120V, 15A or 20A receptacles. Local codes may be more strict, but the NEC doesn't require GFCI protection on 240V general-use receptacles. Or on 120V receptacles at 30A or above.


Greg:
I don't think you can plug normal 15A plugs into that 30A receptacle you have pictured. This website has a good description of the various NEMA plug and receptacle configurations, and I don't see anything in 120V, 30A that mates with 'standard' 15A (or 20A) plugs.
http://www.stayonline.com/reference-nema-straight-blade.aspx

[Pete Brown]

I don't really understand what you are saying here. Why would the load be running through an upstream outlet? I suppose if you were using the receptacle to tie the wires together rather than a using a mar connector? I am not an electrician so I don't know if that is proper. In any case I wouldn't do this and I am not recommending it for anyone else.

I think this discusssion is somewhat interesting but not really germane to the topic so I will bow out now...

Greg

Line and Load. Load goes to other outlets. Line goes back up the chain to the source. This is most important when working with GFCI outlets.

I have no idea what a "mar connector" is.

Pete

[Greg Funk]

Only if they're 120V, 15A or 20A receptacles. Local codes may be more strict, but the NEC doesn't require GFCI protection on 240V general-use receptacles. Or on 120V receptacles at 30A or above.


Greg:
I don't think you can plug normal 15A plugs into that 30A receptacle you have pictured. This website has a good description of the various NEMA plug and receptacle configurations, and I don't see anything in 120V, 30A that mates with 'standard' 15A (or 20A) plugs.
http://www.stayonline.com/reference-nema-straight-blade.aspx

Well I don't have one in front of me but I was pretty sure you could plug a 15A plug into a 15A or a 20A receptacle and it looks like it would fit in a 30A receptacle as well.

[Greg Funk]

I have no idea what a "mar connector" is.

Pete
An incorrectly spelled trade name. In Canada it is common to use "Marr" or "Marrette" connectors for twisting wires together. Not sure what they use in the US.

[Pete Brown]

An incorrectly spelled trade name. In Canada it is common to use "Marr" or "Marrette" connectors for twisting wires together. Not sure what they use in the US.

Ahh. We call them "wire nuts" down here :)

Those show up in the boxes, for sure. Most outlets are wired through, though.

Pete

[Brian Tuftee]

Well I don't have one in front of me but I was pretty sure you could plug a 15A plug into a 15A or a 20A receptacle and it looks like it would fit in a 30A receptacle as well.

Yep, 15A plugs will fit in a 15A or 20A, 120V receptacle. However, if you look at the holes on the 30A, 120V receptacle closely, you'll see they're not compatible with the 20A or 15A plugs.

[Bill Brady]

Everyone needs to remember that the Electrical Codes are in place to protect the public from itself. If there is code rule covering an installation there is a history to go along with the rule. If you want to do your own wiring use a book that follows the latest code. The articles in non electrical trade publications are not always by the code, so be careful of these. And remember if you are not sure what to do call an electrician to do the work for you.