sub feed
- Thread starter domnic
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If there is no EGC with the neutral bonded at the sub-panel and it were lost you could have the potential for a shock.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I say sorta/kinda/maybe depending in what exactly the OP means. If he means " why do we run a separate EGC and neuter instead of just using the neuter as the fault clearing path" then I agree with Rob post #3 that is one of the reasons, but probably more so to just keep neutral currents off expose metal stuff.
why do we run the greeb wire.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
to provide a low impedance path back to the source. to trip an
ocpd and de-energize the circuit in case of a fault. I think you know that, so perhaps some more detail about what you are getting at or what alternative you are considering?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Are you asking why we use an EGC instead of bonding the neutral?
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
The biggest reason a separate ground is run, is due to everything becoming energized if for some reason the neutral has a bad connection or open at the source. This causes everything that grounded thru the neutral bar to become live to other surfaces such as concrete floors, metal building structure, etc.
So that the ground in the subpanel is not affected by voltage drop on the neutral. Basically the same reason branch circuits have a separate ground and neutral.
Your original question about preventing shock in the case of a compromised neutral is a benefit of having a separate ground, but not the reason it’s required - my opinion, of course.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
It helps use up the resources before china does, thats about it.
Buck Parrish
Senior Member
- Location
- NC & IN
It's not required if you're using metal conduit with proper bonding methods.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The equipment grounding conductor can be either metal conduit or a conductor. Some feel that the green wire , equipment grounding conductor, has a less chance of human error (not tightening the couplings etc,) than the conduit. In fact, the conduit is a better conductor than the wire style ground. The conduit has less impedance.
Gives some folks who don't trust the integrity of the conduit a warm fuzzy feeling to see the conductor.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Nothing wrong in having both though. Seen too many conduits used as the egc damaged and separated, and nobody knows about it until someone gets shocked or electrocuted. If the damage is severe enough to break the ground wire, then most likely there will be a short amongst the other wires, causing the ocp to trip.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
See post #16
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
No!
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The only time you bond the neutral to the panel enclosure is in the service equipment. A sub panel is not service equipment
- Status