Multiple recepticals on 220V circuit?

[Cuprousworks]

I've read conflicting answers here and my search on Mike Holt was not productive.

For my shop I want to use multiple 220 outlets. To stay within the Amp total for my panel I would like to run 2 recepticals from a single breaker. As a one man shop I know for my purposes I would never be running both pieces of equipment at the same time, even though the total draw would still be within the breaker's capacity.

But the next person might not use the same equipment or expectations and I don't want to create an unsafe condition. But I also can't see why the conditions would be different than a 110 circuit (draw too much current and the breaker does its thing...)

Also, I think I remember reading where 220 V circuits are not required to have GFCI protection? Is that correct?

Thanks,
Mike

 

[Gummi Bear]

What pieces of equipment are you planning to use on these receptacles?

Motors have their own special requirements, so do welders.

Just having a 220V convenience outlet isn't necessarily a good idea (but also not a bad one, keep reading)

The purpose of a breaker/fuse/overload is to protect both the piece of equipment it serves, and more importantly, you.

If you don't size them properly, you're leaving yourself vulnerable.

If you are just looking for more than one location for say, a welder plug, that's fine. I did that in my own shop (one in the corner, where I do most fab work, and another near a door so I can do trailer or equipment repairs without necessarily having to pull that piece into the shop)

 

[bmwpower]

Sum of all breaker amps does not have to be less than or equal to the total amps of the panel. Doesn't work that way.

 

[Junkman]

What pieces of equipment are you planning to use on these receptacles?

Motors have their own special requirements, so do welders.

Just having a 220V convenience outlet isn't necessarily a good idea (but also not a bad one, keep reading)

The purpose of a breaker/fuse/overload is to protect both the piece of equipment it serves, and more importantly, you.

If you don't size them properly, you're leaving yourself vulnerable.

If you are just looking for more than one location for say, a welder plug, that's fine. I did that in my own shop (one in the corner, where I do most fab work, and another near a door so I can do trailer or equipment repairs without necessarily having to pull that piece into the shop)

The purpose of the breaker/fuse is to protect the wiring, not the devise that plugs into the wiring. If the devise were to draw more current than the wiring could handle, it would go into a melt down state, possibly causing a fire. For this reason, wiring size is specific to the size of the breaker/fuse. For this reason, many devices now have their own "overload" protection in the form of a built in circuit breaker.

 

[PAToyota]

For both my woodshop as well as the downstairs metalshop/garage I have 220V "convenience" circuits as you describe for various 220V equipment that gets moved around - dust collector, planer, etc... Haven't had any problems with it.

 

[Gummi Bear]

The purpose of the breaker/fuse is to protect the wiring, not the devise that plugs into the wiring. If the devise were to draw more current than the wiring could handle, it would go into a melt down state, possibly causing a fire. For this reason, wiring size is specific to the size of the breaker/fuse. For this reason, many devices now have their own "overload" protection in the form of a built in circuit breaker.

Yes, and no.

That is a well thought out response, and I agree with your reasoning, but not the definition of the application. "Branch circuit conductors shall have an ampacity not less than the maximum load to be served" (210.19(A)(1))

You cannot rely on a piece of equipment to have it's own overcurrent protection, often times they don't.

That's why I asked what he intended to use the circuit for. Motors and welders have their own special requirements (NEC articles 430 and 630), and what works for one, isn't necessarily well suited for another.

That's the funny thing about the code, two electricians can argue about it just like two lawyers in a courtroom, and while both can make a convincing case, neither one is necessarily wrong. It's all in the interpretation.

 

[PAToyota]

And I'll split the difference...

Junkman is right about protecting the wiring. Truthfully, the code cares little about what you plug into the receptacle and how it is protected. The breaker is sized to protect that wiring and receptacle. But Gummi Bear picks up from there - you don't want to oversize the circuit and leave the equipment unprotected.

My dedicated circuits for air compressor, welders, plasma cutter, and TIG welder are all sized with the protection of the equipment in mind. As stated above, I also have 20amp 220V "convenience" circuits for smaller 220V equipment.

 

[markb1]

The National Electrical Code was written for ,fire safety and shock hazard with the aid of the National Fire Protection Agency (NFPA) updated every three years for the last 100yrs.

Why anyone would want to go outside the code and risk possable shock and burn for yourself or others is beyond me.

Often people alter or do substandard work then move and leave a new owner with potential safety issue.

Just my .02

Mark

 

[ZRX61]

You could pretty much have a circuit with 100 220v outlets on it if you were only using one at any particular time..

 

[PAToyota]

Why anyone would want to go outside the code and risk possable shock and burn for yourself or others is beyond me.

All the wiring in my shop meets NEC code. But you have to understand the code and what it protects. You can have a circuit that meets all the codes and but is oversized for the equipment and does not protect it.

I haven't seen anything discussed here prior to your comment about bypassing the code...

You could pretty much have a circuit with 100 220v outlets on it if you were only using one at any particular time..

Actually, the code does limit the number of receptacles on a circuit...

 

[MustangRick]

For your comment about the next guy... If you make up a wiring diagram and have it near the breaker box, then you are doing more then anyone else does for the next owner. Besides, if two devices pull too much, the breaker should settle the fight before anyone gets hurt. For the GFCI, I have never seen a GFCI 220 outlet, I assume that it would have to be in the breaker. I do remember something in the code about starters and dedicated outlets were exempt from GFCI, but I am not an expert.

 

[markb1]

IF....and..... SHOULD....

But it didn't and the garage burned.

Oh well I left the guy a diagram.

Maybe that breaker was bad... probably because it tripped so many times when they were running those heaters.

He should have known better.

 

[Junkman]

Re: Multiple receptacles on 220V circuit?

I know that jetted bathtubs and hot tubs are on dedicated 220 volt GFI breakers, and I assume that it is code required. When I purchased the heated / jetted American Standard tub, it didn't give any comments other to say that it needed to be wired in compliance with all Local and State codes.

 

[JCByrd24]

How many would run a separate 15A 220V circuit for a tablesaw (only 7.5A at 220V anyway, but isn't 15A, 14awg the smallest you can run) instead of just sharing a 20A 220V circuit (12awg of course) with a compressor (15A @ 220V). By sharing I mean 1 receptacle, you have to unplug 1 to use the other. In this case the table saw gets basically no protection from the breaker (over built circuit), but neither does it with the 15A circuit. It does have its own thermal overload. Sorry if this is considered a hijack, but kind of related.

Ok, to keep it more related. How many would wire the multiple receptacles to the 1 20A circuit and hope the compressor doesn't kick on while you're running the table saw and let the breaker do its work if that happens. I'm guessing a guaranteed trip when the compressor starts unless maybe the saw is freewheeling??

PS. I'm doing the 1st.

 

[Cuprousworks]

This would be for powertools: table saw, jointer, bandsaw, etc. There is a second 220 line dedicated to the dust collector which is a different circuit because I expect it would be used at the same time.

All of the equipment is convertible from 110 to 220, so the amp draw at 220 is only expected to be 7.5 amps after startup, it would be a 20 amp 12/2 w/g setup.

I know that my breakers aren't limited by the master breaker (90amps). But the panel is relatively small and includes a note about the maximum allowable amps per side on the warnings/instructions pasted inside the door. I'm quite sure I will never worry about the total 90 amp draw, but I've made liberal use of conservatively designed 20 amp circuits for convenience, lighting, bathroom and dedicated (sump) and I would like to maintain enough capacity to add an air conditioning unit (high amperage draw) in the future without exceeding the panel limits.

Thanks,
Mike

 

[thefairlaneman]

I have one dedicated 220 in the corner oposite the breaker panel for the air compressor and another 220 outlet wired directly under the panel for the welder. What other 220 needs to you plan to have?

 

[goodfellow]

I struggled with this problem as well, and like others here I couldn't find a clear solution. In the end I ran three seperate circuits

1) 100 A for the heavy duty welders (Dialarc HF and Synchrowave 300) with 100 A Arktite connectors -- (Crouse Hinds type plug and receptacle)
2) 30 A for the compressor
3) 50 A (with multiple outlets) shared among the Plasma Cutter, MIG and two medium duty welders)

Since I need to move the HD welding equipment frequently I made a 50' 1/0 extension cord with an Arktite 100 A plug and receptacle.

The circuit diagram was posted inside the subpanel.
I'm a one man hobby shop -- so this has worked well.

 

[DynoDave]

This is interesting reading, all. I haven't started to sketch out my plans for wiring yet. I know I want at least 1 220v outlet in the corner for a compressor (eventually) and a MIG (eventually; my current welder and compressor are 110v). Also, the plans call for a window a/c unit. I was originally going to get a 110v a/c, but my HVAC guy suggested getting a 220v unit, as it would be more efficient, and cost less to run. Was actually looking at them at Lowes last night.

So I guess I was leaning toward a (2) 220v outlet plan, one for the a/c (I don't want to have to unplug it every time I need air or the welder), and one to be shared (1 unit at a time) by the compressor and the welder.

If I read/summarize the above correctly, the only "risk" in doing this would be that the equipment could be damaged by drawing too much current, but not the wiring as it would be breaker protected. Is that right?

 

[W-Cummins]

NEC rules say that Multi receptacles are allowed on branch curcuits. Voltage dose not make any diffrence as far as the code goes.

If I read/summarize the above correctly, the only "risk" in doing this would be that the equipment could be damaged by drawing too much current, but not the wiring as it would be breaker protected. Is that right?

The equipment will not draw too much current very long, the breaker ( if sized correctly) will turn off. What you can not do ( or at least should not do) is run light stuff on heavy amp circuits ie. try to run 20 amp stuff on 50 amp outlets. Now of course the NEC tries to prevent this, but they really have NO way to do that as their inspection powers end at the outlet. They can't stop some idiot from cutting off the 15 amp plug off his table saw and putting on a 50 and plugging it in!!

Where this all gets on a slippery slope is when you add circuits that are intended for use in an industrial setting and put them into your residential garage. ( like large motor and welder circuits ) you can do things with the breakers and wiring on those circuits, that if you attach them to receptacles for a plug attached devices, can lead to problems down the road... So you can have a 50 amp range receptacle that may be set up to run a large compressor circuit, and have an over sized breaker ( up to 250% ) that would not be allowed for a normal 50 amp range outlet.

William.....

 

[markb1]

NEC 210.23
In no case shall the load exceed the branch circuit ampere rating. An individual branch circuit shall be permitted to supply any load for which it is rated. A branch circuit supplying two or more outlets or receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D) and as summarized in 210.24 and Table 210.24

210.23 (A)(1)
Cord and plug connected equipment.
The rating of any one cord and plug connected utilization equipment shall not exceed 80 % of the branch circuit ampere rating.

210.23(A)(2)
Utilization Equip. Fastened in Place.
The total rating of utilization equip. fastened in place, other than lighting fixtures shall not excede 50% of the branch circuit ampere rating where lighting units, cord and plug connected utilization equipment not fastened in place, or both, are also supplied.

 

[W-Cummins]

NEC 210.23
In no case shall the load exceed the branch circuit ampere rating. An individual branch circuit shall be permitted to supply any load for which it is rated. A branch circuit supplying two or more outlets or receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D) and as summarized in 210.24 and Table 210.24

210.23 (A)(1)
Cord and plug connected equipment.
The rating of any one cord and plug connected utilization equipment shall not exceed 80 % of the branch circuit ampere rating.

210.23(A)(2)
Utilization Equip. Fastened in Place.
The total rating of utilization equip. fastened in place, other than lighting fixtures shall not excede 50% of the branch circuit ampere rating where lighting units, cord and plug connected utilization equipment not fastened in place, or both, are also supplied.

Yep these are what I like to call the NEC fantasy codes. The first 2 are total dream land for them they are TOTALLY unenforceable. The last one can be enforced if the fastened in place equipment is there BEFORE the final inspection. Other wise they are just not in effect for the "home owner". Now if your running a business or some thing that requires that you submit to inspections ( fire???) I guess they could effect you. I have never seen the fire inspector checking breakers and wire gauge though....

William...