Ground and Neutral bonded at service box - Electrician Talk - Professional Electrical Contractors Forum

electricnut · 10-03-2009, 08:59 AM

What is the difference in bonding the neutral and ground at the service box as opposed to an auxillary panel, isn't it the same?

Magnettica · 10-03-2009, 09:18 AM

Quote:

Originally Posted by electricnut

What is the difference in bonding the neutral and ground at the service box as opposed to an auxillary panel, isn't it the same?

No, because a grounded "neutral" conductor is a current-carrying-conductor (CCC) in a 2-wire circuit. If neutral and ground were bonded at any place other than at the main breaker you would have current flowing on the normally non-current-carrying parts. You don't ever bond a neutral and a ground at a receptacle in a metal box do you?

Toronto Sparky · 10-03-2009, 04:09 PM

Added to that you would create a unbalanced magnetic field.

sparks134 · 10-03-2009, 07:23 PM

you can only bond the neutral and ground only at the main disconnect, if not you can really hurt/kill somebody!!!

electricnut · 10-03-2009, 07:56 PM

you can only bond the neutral and ground only at the main disconnect, if not you can really hurt/kill somebody!!!
Hey can you explain why???

Speedy Petey · 10-03-2009, 09:05 PM

The buzz words here are "objectionable current".

http://www.mikeholt.com/mojonewsarch...t~20020610.htm

Magnettica · 10-03-2009, 10:22 PM

Quote:

Originally Posted by Speedy Petey

The buzz words here are "objectionable current".

http://www.mikeholt.com/mojonewsarch...t~20020610.htm

Live it, learn it, love it.

220/221 · 10-05-2009, 10:30 PM

If the neutral and grounds are together in a panel and you lose the neutral feeding that panel, the current will try to flow thru any available path to ground trying to find it's way home.

This could energized metal components of anything grounded and attached to the system.

Toronto Sparky · 10-06-2009, 02:24 AM

Quote:

Originally Posted by Toronto Sparky

Added to that you would create a unbalanced magnetic field.

Unbalanced magnetic fields running though a ferris metal raceway could create a condition that will heat up the raceway to the point of fire..

Stator · 10-31-2009, 04:22 PM

Whoever said that the only place you can ground a neutral is the service panel is not correct. What happens if your incoming water piping is non-metallic??

Use a ground plate outside right next to the meter, attach the correct size ground to it, then "Ground" the neutral inside the meter base. Pick up a dual lug so that you have room for the house neutral and the ground.

Then remove the bonding strap from the panel, run the ground through your conduit or Teck cable (I much rather use Teck cable) and ground your service panel at the ground bar.

Ok let the bashing begin....

Speedy Petey · 10-31-2009, 05:20 PM

RIVETER · 10-31-2009, 06:17 PM

Quote:

Originally Posted by Toronto Sparky

Unbalanced magnetic fields running though a ferris metal raceway could create a condition that will heat up the raceway to the point of fire..

I don't know what you mean. I've never considered "unbalanced magnetic fields", has anyone else?

cdnelectrician · 10-31-2009, 07:31 PM

Quote:

Originally Posted by RIVETER

I don't know what you mean. I've never considered "unbalanced magnetic fields", has anyone else?

Ya, not too sure about that one...but I could see those cheap chinese cast conduit connectors melting away lol I think maybe you mean eddy currents in single conductor cables surrounded by ferrous metal operating above 225 amps.

EJPHI · 10-31-2009, 07:46 PM

Quote:

Originally Posted by RIVETER

I don't know what you mean. I've never considered "unbalanced magnetic fields", has anyone else?

This is an important point.

If the ground and neutral are connected at the main panel or upstream from it (meter base), then the bonded metal only forms a return path when a fault occurs from line to ground.
So if the fault occurs it should be cleared by the overcurrent device. In other words this is a temporary condition.

If you connect the ground and neutral down stream from the main panel as well as in the main panel, all bonded metal becomes part of the path for the neutral current. This is not a temporary condition, as described above, and it will have two direct consequences:
1) The current flowing through the bonded metal will cause it to warm up due to resistive heating.
2) Since the line and neutral return paths are not "tight" like they would be if all of the return current flowed in the neutral wire in the same reaceway or cable as the line wire, a wide-area magnetic field is formed. This field will induce currents in the bonded metal or any other conductor forming a closed path that encircles part of the wide-area magnetic field. The induced current will cause the metal to heat up. Eddy currents will also cause heating even if the metal does not encircle the magnetic field

I expect that there isn't enough current in most resi branch circuits to cause noticable resistive or inductive heating with improper ground/neutral connections. You might notice that an AM radio has a lot 60 Hz hum when tuned off station. Kinda like the first three way I wired

Because the small voltage drop across the metal sharing the neutral current, there wouldn't even be any touch potential.

EJPHI

RIVETER · 10-31-2009, 08:06 PM

Trick or treaters at the door...gotta go.

Stator · 10-31-2009, 10:45 PM

Quote:

Originally Posted by Speedy Petey

Exactly. Then run a ground to the service and remove the bonding strap. Land the ground at one of the ground bars.

RIVETER · 10-31-2009, 11:19 PM

Quote:

Originally Posted by Toronto Sparky

Added to that you would create a unbalanced magnetic field.

I am still not with you,there.

RIVETER · 10-31-2009, 11:23 PM

Quote:

Originally Posted by Stator

Exactly. Then run a ground to the service and remove the bonding strap. Land the ground at one of the ground bars.

Am I the only one who does not understand this pictorial?

bobelectric · 11-01-2009, 12:15 AM

Quote:

Originally Posted by Speedy Petey

I never saw a ground point at the service head. If it was up to me,all service entrances would have the meter with the main breaker with all grounding outside for lightning protection with the ground rods. And shut off for fire safety.

EJPHI · 11-01-2009, 01:13 AM

Quote:

Originally Posted by bobelectric

I never saw a ground point at the service head. If it was up to me,all service entrances would have the meter with the main breaker with all grounding outside for lightning protection with the ground rods. And shut off for fire safety.

I am 100% with Bob on this.

On the one hand what could be difficult about connecting a silly green wire? But as you look into all apsects of grounding and bonding, you can see that there is a lot of thought behind the NEC.

EJPHI