A friend of mine who is a mason received an OSHA fine for not having GFI protection on a 220 volt wet table saw on the jobsite. The 220 volt line comes out of a 30 amp breaker panel consisting of 2 hot wires and a ground and is attached to the saw with a male and female plug. My understanding is that GFI's monitor the neutral. The saw does not require a neutral in order to work, and GFI's won't work on motors. Is there a way to have GFI protection on the saw?
GFI protection on motors
- Thread starter sparky1
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ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: GFI protection on motors
I think it is important to remember the fact that there is an alternitive to the GFCI requirement of article 527, and that is the "assured equipment grounding program". I think instances like this could perhaps be avoided by implementing it.
I think it is important to remember the fact that there is an alternitive to the GFCI requirement of article 527, and that is the "assured equipment grounding program". I think instances like this could perhaps be avoided by implementing it.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: GFI protection on motors
Sparky1:
So you can use a two pole GFCI eather type and if you dont need the neutral then just dont hook any thing up to it Now this is not the neutral that goes from the breaker it self to the neutral bar this wire always has to be hooked up and both types of GFCI's have this wire but the load neutral terminal is the one that does not have to be used and the breaker will still work.
Sparky1:
This is a wrong statment. There is GFCI's that are made for 2 pole's and will work without a neutral and even work without a neutral or a ground as these are not needed for it to function. in a twopole GFCI there are three conductors going through the current coil that they use in a single pole version. There are two types that are twopole one has a place for a neutral and one doesn't eather can be used as the neutral only serves as a return path for the current that is being used from it like a 120 volt clock or timer. if there is no current on the neutral then the current on each hot must equal the other. as long as the current is equal the breaker wont trip but if there is more on one than the other this means that current is being pulled from somplace else Ie. ground, then it will trip if this current is higher than 5ma.
So you can use a two pole GFCI eather type and if you dont need the neutral then just dont hook any thing up to it Now this is not the neutral that goes from the breaker it self to the neutral bar this wire always has to be hooked up and both types of GFCI's have this wire but the load neutral terminal is the one that does not have to be used and the breaker will still work.
Re: GFI protection on motors
If you have a clamp on amp meter you can see the principal that a GFI uses. If you put your meter around one conductor you will read the amps. If you put the meter around all of the conductors going to the load you will not get a reading since the magnetic fields cancel each other. If you have a ground on one conductor part of the current then flows in the EGC (hopefully) and the magnetic fields are no longer balance. You would then get a reading on your meter equal to the amount flowing in the EGC. This is a basic explanation and I am sure others can explain it better.
If you have a clamp on amp meter you can see the principal that a GFI uses. If you put your meter around one conductor you will read the amps. If you put the meter around all of the conductors going to the load you will not get a reading since the magnetic fields cancel each other. If you have a ground on one conductor part of the current then flows in the EGC (hopefully) and the magnetic fields are no longer balance. You would then get a reading on your meter equal to the amount flowing in the EGC. This is a basic explanation and I am sure others can explain it better.
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