electrical question on 30A outlet

[xrongor]

i just got done wiring my garage and as we forgot to buy one, he just told me to go buy one later and put in a 220V 30A outlet. we wired it to the panel and all, just left the wires loose in the box which is located right below the panel.

the electrician told me to run the copper wire to the neutral prong instead of the white wire. his reasoning was that a loose copper wire in the box could accidentally touch one of the lugs that was hot, but you could just wire nut the neutral and it wont touch anything. this way i dont have to trim off the copper ground wire and if i ever need to i can switch to a 4 prong outlet instead of a 3 prong one.

now i know how the neutral and the ground are related and connected, and i dont see a problem. but im not an electrician.

so my question is, is the inspector gonna have a fit or is this a common practice?

randy

[xrongor]

sorry, meant to post on home.repair. but if anyone knows the answer, would be appriciated.

randy

[Roy Smith]

What kind of receptacle did you put in? "220V 30A" could be one of several. Take a look at

The receptacle you bought should have a NMEA number, something like 6-30R, 10-30R, etc. They get wired up different ways. Without knowing which you put in, it's impossible to tell if you did it right or not.

[Scott Lurndal]

Assuming a metal box, you must mechanically bond the grounding conductor (the bare copper conductor) to the box itself. The grounded conductor (the white or gray conductor) must _not_ be bonded to either the box or the ground_ing_ conductor.

For a plastic box, you can either trim the grounding conductor if you are sure that the recepticle you have doesn't need it, or tape it or leave it alone (unconnected). Were it to contact a current carrying conductor, the circuit breaker will trip, so taping it will prevent vibration from causing any future problems.

I personally would not connect the grounded conductor and grounding conductor together at the device under any circumstances, but especially if the device is downstream from a subpanel (where it would be a code violation).

scott

[xrongor]

after doing research, it seems i have a 10-30R type outlet. i want it for a welder/heater/general use in the shop. so it sounds like the way its wired is with no neutral and the third prong is a ground.

since i already have the 4 wires there, maybe i should replace it with an outlet that accepts all 4 directly. the box is all fiberglass and there is NO metal strap or hole to put a ground screw into.

i guess what i really want to know comes down to this. given that i already have the 4 wires going to the box, if not simply using the 10-30R wired with a ground and no neutral, which type of outlet would be the best to install here for a general use garage 220V outlet?

thx randy

[Roy Smith]

I don't have that much experience with welders, but I believe 230V/30A service is just not enough for anything but the smallest machines. I would recommend you look up the specs for the unit you're thinking of buying and see what it requires.

My reading of the diagram is that the third pin should be connected to the neutral (white), not ground (bare) wire.

Once you get past 115V/20A, things get a lot less standardized. I'm not sure there is a good answer to your question. The real answer is "you need whatever receptacle fits the plug on what you want to plug in". A

6-20R is probably the right thing for most 230V woodworking machinery in the 2-3 HP range, accepting either a 6-15P or 6-20P plug. But that's just a guess, not a promise.

When you get into industrial equipment, and really high power draw things like electric dryers and stoves, arc welders, and space heaters, you'll find that many things don't even come with cords. They come with terminal blocks, with the expectation that you'll supply your own cord, or perhaps hard-wire it.

[xrongor]

i think this is the meat of the issue. put whatever outlet you need on it .

the plug i have is wired properly for the heater i have. i only plan on using a small mig welder so ill worry about it when i get it. worst case, ill wire up two outlets. i have plenty of capacity in the shop (100A main). so for now i think im good.

thx mucho.

randy

[DarylRos]

Now a more important question is this: Why are you trying to do this yourself? If you have to ask how to run a 30 amp line, then you are asking for a fire, electrocution or worse. You mess witha 110 15A line you get a shock. You start at 220, and you up the amperage, you are asking for major trouble. And more buckes then you save.

[xrongor]

if you think 220 is really that dangerous, you cant know that much yourself. much of the cilvilzed world has 220 to the outlets just waiting for kids to stick knives and screwdrivers into them. they survive.... for some reasons americans are taught that 220v=instant death.

i know how electrons work, i dont know the CODE.

and daryl, im finding out that wiring a 10-30R with the ground connected to the third prong of a 10-30R and the neutral taped up is actually a common thing to do because a 10-30R costs less than a 14-30R and things like heaters and welders dont use the neutral anyway.

but hey, thanks for the input!

randy

[Tom Veatch]

Paraphrasing a sig. line I've seen here, "In theory, theory and practice are the same. In practice, they're not." In that light, can a knowledgeable electrician in the audience explain a practical reason for the above practice being a code violation?

Since the grounded (white) and grounding (green/bare) wires are electrically connected at the panel - both are attached to the same bus - why is it significant if they are also connected together downstream from the panel. In theory, they will both be at the same potential (ground) due to the panel connection.

Tom Veatch Wichita, KS USA

[Greg]

If this branch circuit originated from the panel with the main bonding jumper and they were on the same bus that would be technically true but if it was from a sub panel where grounds and neutral are separate, there would be neutral current flowing in the ground. There is also a violation when you parallel small conductors but I won't kick that tar baby here. Since 1996 neutrals and grounds are not supposed to be confused in receptacles. The range and dryer exception went away then. They decided WWII was finally over.

[Charlie Mraz]

are the same. In practice, they're not." In that light, can

the above practice being a code violation?

electrically connected at the panel - both are attached to the same

from the panel. In theory, they will both be at the same

The neutral and ground should only be connected at *ONE* point, being the busses in the breaker box. This is why subpanels have the two busses separated. The ground conductor is for safety, and should not carry current under normal circumstances. If you connect the ground and neutral at the box, they will share the current roughly equally (assuming similar resistance). Also, it can cause ground-loop noise, which is not a concern for motors and lights and the like, but it could make for a very noisy stereo system.

Charlie

[Chipper Wood]

FWIW. The key is the voltage that will be used...... If all of the devices that will be used are single voltage 240 V. Then the ground should be used on the third connection. Fire Underwriters requires any electrical device with metal parts that might become accidentally energized must be grounded. A neutral is not an acceptable grounding conductor. A ground conductor shall not be used as a neutral. If any device to be used is 120/240 V. Then the 4 wire outlet must be used.

Usually 240 V. outlets are for a single device and serve as a disconnect for servicing or emergency of only one unit. The amperage rating is for maximum current disconnect. ( of course use also.) If one is using the outlet for multiple devices, it must conform to the grounding rules for each device used.

[Tom Veatch]

Thanks, Greg and Charlie.

I think that puts the requirement on a more rational basis. And Greg, believe it or not, I'd already figured out a logical reason for the "don't parallel small conductors". I'm planning to increase the branch to my shop from 60 to 100 amps when I enlarge it and add on an equipment shed. The existing line won't handle the higher load so a new, larger (read as "more expensive") wire will have to be laid.

Tom Veatch Wichita, KS USA