neutral after being bonded - Electrician Talk - Professional Electrical Contractors Forum

jayare813 · 07-08-2009, 05:52 PM

Is there a certain distance or circumstance that the neutral and ground wont ring out after being bonded. For example after the mdp the grounding and grounded are still riniging but if we the install another panel from mdp and do not bond the grounded and grounding will it still ring out to the devices, loads, etc.

InPhase277 · 07-08-2009, 06:18 PM

Quote:

Originally Posted by jayare813

Is there a certain distance or circumstance that the neutral and ground wont ring out after being bonded. For example after the mdp the grounding and grounded are still riniging but if we the install another panel from mdp and do not bond the grounded and grounding will it still ring out to the devices, loads, etc.

Neutral and ground will always ring out, no matter how many panels you put between you and the MDP, if properly installed. Each subpanel has its own ground wire back to the MDP, where it is bonded to the neutral. Continuity will always be present back to that Main Bonding Jumper.

vinster888 · 07-08-2009, 08:31 PM

the only time i have not seen them ring out when in a correct system is on the load side of a tripped gfci

william1978 · 07-08-2009, 08:50 PM

Yes, they should always ring out.

waco · 07-08-2009, 09:04 PM

I agree. Look for corrosion at the the service.

Richard Rowe · 07-08-2009, 09:15 PM

Yep should ring out, look for a bad jumper or connection. You will find it in th panel somewhere.

brian john · 07-08-2009, 10:58 PM

Quote:

Originally Posted by InPhase277

Neutral and ground will always ring out, no matter how many panels you put between you and the MDP, if properly installed. Each subpanel has its own ground wire back to the MDP, where it is bonded to the neutral. Continuity will always be present back to that Main Bonding Jumper.

has its own ground wire back to the MDP, Actually not always, It will have a ground conductor (EMT, BX or other metallic raceway). Not necessarily a WIRE.

InPhase277 · 07-08-2009, 11:33 PM

Quote:

Originally Posted by brian john

has its own ground wire back to the MDP, Actually not always, It will have a ground conductor (EMT, BX or other metallic raceway). Not necessarily a WIRE.

You do much hair splitting at work too?

goose134 · 07-08-2009, 11:38 PM

Quote:

You do much hair splitting at work too?

It always sounded like he made a pretty successful career out of it.

Brian, I mean this in the best way.

brian john · 07-09-2009, 11:23 AM

Quote:

Originally Posted by InPhase277

You do much hair splitting at work too?

It is a follow up on that post regarding "do I need to use a EGC conductor in EMT". I knew you knew what you meant. Just an adder.

Quote:

Brian, I mean this in the best way

I knew that.

waco · 07-09-2009, 11:51 AM

Does raise an interesting point for discussion. I never rely on anything except wire to serve as the ground to a sub-panel. In fact, I was probably taught that a sub-panel had to have a four wire feed and just never questioned it.

Jeff000 · 07-10-2009, 09:20 AM

What do you mean by "ring out"?

cmec · 07-10-2009, 10:27 AM

Quote:

Originally Posted by waco

Does raise an interesting point for discussion. I never rely on anything except wire to serve as the ground to a sub-panel. In fact, I was probably taught that a sub-panel had to have a four wire feed and just never questioned it.

A peice of 2 in emt and a peice of # 4 copper what has more surface area?, whats a better path back, as long as its not broken or ate off in the concrete.

I agree emt should have an egc, but the nec dosent require it.

waco · 07-10-2009, 10:43 AM

Quote:

Originally Posted by cmec

A peice of 2 in emt and a peice of # 4 copper what has more surface area?, whats a better path back, as long as its not broken or ate off in the concrete.

I agree emt should have an egc, but the nec dosent require it.

We agree on the use of an EGC. I think the wire is far more reliable and as other design requirements increase its importance, I think the wire should be the norm.

brian john · 07-10-2009, 04:21 PM

In most commercial applications there are multiple paths for ground return, multiple EMTs, ducts, structural steel, domestic water, sprinkler pipes, rebar in the concrete.

cmec · 07-10-2009, 04:31 PM

Quote:

Originally Posted by brian john

In most commercial applications there are multiple paths for ground return, multiple EMTs, ducts, structural steel, domestic water, sprinkler pipes, rebar in the concrete.

Thats why we use redundant grounds in healthcare facilities

raider1 · 07-10-2009, 04:44 PM

Quote:

Originally Posted by waco

We agree on the use of an EGC. I think the wire is far more reliable and as other design requirements increase its importance, I think the wire should be the norm.

Steel conduit is a far superior fault current path than a copper wire.

HERE is a link to the steel tube institute of America. There are a bunch of papers and software programs that show this.

Quote:

That's why we use redundant grounds in health care facilities

The redundant ground for a health care facility is the insulated copper conductor. The primary ground fault current path is the metallic wiring method itself.

Chris

cmec · 07-10-2009, 04:53 PM

The redundant ground for a health care facility is the insulated copper conductor. The primary ground fault current path is the metallic wiring method itself.

Chris[/quote]

What I am trying to say is if they are not concerned about noise or transient or gradiant currents,or unequal ground potental its ok to use conduit for an egc.

brian john · 07-10-2009, 05:04 PM

Quote:

Originally Posted by cmec

The redundant ground for a health care facility is the insulated copper conductor. The primary ground fault current path is the metallic wiring method itself.

Chris

What I am trying to say is if they are not concerned about noise or transient or gradiant currents,or unequal ground potental its ok to use conduit for an egc.[/quote]

In 100% of the cases where I have investigated Isolated ground systems (not hospital grounding systems) ALL were improperly installed.

cmec · 07-10-2009, 05:43 PM

Brian I think a lot of it has to do with code requirements and how things have evolved, I can rember people driveing seprate ground rods for ig s on cash registers back in the 70 s, then it was out lawed ,its only 2 or 3 code cycles ago we started putting a ground buss and tieing streel pipe etc together.With all the electronics today it gives us work in a recession.