Short circuit test

That's a good point about potential to ground. I never thought about that. I could see myself finding both hot ends, but then I don't think a GFCI would help any way.
I was told that the builders in NC fought hard against code changes. My house built in 2006 only has GFCI to the bathrooms and kitchen.
Robert
 
I had a motor at one time that worked really well. Only problem at some point the varnish on the windings had got scratched off making a short. It had push buttons on the bell housing for one off of the motor . Worked fine as long as it wasn't grounded. Had it hooked up to a little air compressor. If you touched a ground you got a tingle. Far as I know it's still in my old shop working with a sign on it don't touch shock hazzard. I always ment to respray the windings but always had more to do then time to do it. Besides lay your sweaty arm on some metal your welding that tingles too.
 
I don't know where it sits currently with the code panel, but last I heard they were actually looking at extending the GFCI requirement to all 240V 15A and 20A receptacles as well in wet areas, garages, basements etc. It is very possible that it will be a requirement in the 2017 code anyways. As of the current 2014 code it is only required on 120V 15A and 20A circuits.
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Nothing listed in the code change listing I saw. They did clarify unfinished basement and work, storage areas as far as GFCI requirements.
 
Nothing listed in the code change listing I saw. They did clarify unfinished basement and work, storage areas as far as GFCI requirements.

I just took a look at the revisions. Looks like they went half-way. They are requiring it for non dwelling units. That would apply to detached garages, detached shops (assuming it is an outdoor outlet, or the shop has a 'garage door' in it and inspector considers it capable of garaging vehicles, etc). That means that the next cycle they will push it on dwelling units including attached garages, basements etc, the next goaround. :)

Language from the 2017 NEC is below with the changed section underlined. Since split single phase < 150V to ground on each leg, this would apply to all 250V single phase receptacles 50A and smaller . Will be fantastic for welders!

Looks like we can thank Schneider Electric for submitting this change. I am sure they only have our safety in mind. It would, of course, have nothing to do with the fact that they own SquareD, the makers of GFCI circuit breakers.

210.8(B) Other than Dwelling Units. GFCI protection is required for single-phase receptacles rated 50A or less not exceeding 150V to ground and 3-phase receptacles rated 100A or less not exceeding 150V to ground installed in the following locations:
 
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Do not worry about gfi on your machines but do worry about wiring them correctly and this is stupid simple.

First check the breaker that supplies the tool.

Say it is a 30 amp breaker.

That determines the wire size for all wires (assuming correct size for machine)

Up to a certian size the safety ground needs to be same size as breaker rating as it has only one job to trip that breaker.

Next establish your point of entry to the machine and this should be near the motor or control panel but should be a sturdy point.

Next determine if safety ground is included in power cord or seperate.

This example is using power cord for safety ground.

Attach safety ground to the frame or casting of the machine if possible with a bolted on connection to a clean and shiny spot.

Add additional wires from anything that has power to the frame as well as between any parts that are painted interfaces.

Example is motor as it should have a seperate braided strap from a motor bolt to a frame bolt as the mount often swivels or maybe cushion mount.

Last route all power wires neat and clean so they do not pinch or bind as well as insuring all covers and insulators are proper.

Next last is to have all powee wires in conduit once it gets past point of entry so it is protected from chips causing shorts or you snagging a wire.

The gfi looks at current flow in both wires to the equipment and trips if one is more than the other indicating current leaking to ground possibly via you.

If no wire is placed where you can touch it and every conductive item in the machine is bonded together and to ground any internal short would be routed right back to the load center and the breaker would trip.

You would feel zip.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
You checked voltage between each leg and a known good ground and got 99VAC on one and 12VAC on the other? That is a problem. One leg should be reading around 120V and the other 0V (the neutral). Either the ground you used to test this wasn't good after all, or there is something going on with your neutral bond in your panel somewhere. That looks like the neutral at that receptacle is 'floating'. Obviously an extension cord with a broken ground is a problem, but you may have more than one issue here...
I agree with the above one leg should be 110/120 volts ac and the other zero if measuring to a good earth point.
The fact you are measuring 12vac indicates that the neutral leg is floating above ground potential. This may be a high resistance in the neutral line or the connection bus in the meter box linking the neutral to the main earth.

I suggest first doing the same test directly at the power point and if this gives the same results then test the neutral link to earth connection at the board for high resistance and also the neutral link to a known earth. This should be less than 2 ohms over all (Australia). But only if you are confident/competent in this as it has a danger associated with it, as does everything in life.

Overall do not use the equipment before it is fixed as it can go at full mains potential at any time
 
I was trying to find a resource to see how many deaths there are in the USA from in home electrical shocks. It's very hard to find a clear answer. Maybe they want it that way. I am not talking about the idiot who puts a ladder on the high voltage line or a work place accident; just the regular kind of shock you get from a plug or appliance. Some sources also lump in deaths from electrical fires also to inflate the figures. Water seems to be the biggest factor in death versus injury. My suspicion is the number is very low. Looks like Ireland averages about 1 per year.
Robert
 
Back when I wore a Safety Manager's hat, an OSHA inspector showed me that the way he would check for an improperly grounded piece of equipment was to hold a non-contact voltage detector (aka volt tick) close to the frame of the equipment. If it chirped, there was a faulty ground.
 
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