BONDING

[johnsonl]

Re: BONDING

ROGER,

Its interesting that you cannot recognize the need for maintenance of electrical equipment.

Valley Electric's TEGG?/Service Division: TEGG? Service Contractors specialize in proactive predictive maintenance on electrical distribution systems. The services our division provides are:

Preventive Maintenance Objectives: Ongoing preventive maintenance tasks are vital in helping to extend the life of electrical distribution equipment, and to assure proper operating conditions and efficiency. The National Fire Protection Association for the safe usage of electrical power and equipment recommends the annual walk through.

Avoided Facility Risks: Dirty equipment and loose connections decrease the efficiency and life expectancy of electrical distribution equipment. Abnormally dirty equipment can cause circuit breakers and other electrical components to fail to operate, or operate prematurely. Catastrophic failure of electrical equipment can occur leading to costly down time and replacement costs.

 

[roger]

Re: BONDING

Johnson, first of all you didn't address the thread topic, second: why is an inspector advertising for TEGG?, third: how does my post indicate I don't recognize the need for maintenence? PM is a big part of our business even without TEGG?. :roll:

I simply asked you how you would maintain a connection which you haven't answered.

Roger

[ March 05, 2004, 06:57 PM: Message edited by: roger ]

 

[iwire]

Re: BONDING

Johnson I will let you figure out Rogers experience level on your own.

Bob

[ March 06, 2004, 10:08 AM: Message edited by: iwire ]

 

[don_resqcapt19]

Re: BONDING

There is no reason to install this bonding jumper and as other have pointed out there would be a violation of 310.4. Look at 250.92(B)(1). The only required bonding in this case is a connection to the grounded conductor at both the meter and the service panel.
Don

 

[johnsonl]

Re: BONDING

310.4 Conductors in Parallel

310.4 is talking about the criteria necessary in order to utilize conductors in parallel to handle more amps than a single conductor could itself achieve alone.

Bonding the grounded conductor to a the enclosure ensures that the grounded conductor and the enclosure are at the same potential, and provides a effective fault current path.

Bonding the two enclosures together with a jumper satisfies 250.4(A), 250.90, and 250.92 (A) (2).

250.92 (B) is talking about bonding the enclosure to the grounded conductor.

250.4 (A) covers the general requirments for "Grounded Systems".

One just can't pick and choose which part of the code he or she wants to use, for all of the code, where it applies, must be used.

 

[iwire]

Re: BONDING

Originally posted by johnsonl:
One just can't pick and choose which part of the code he or she wants to use, for all of the code, where it applies, must be used.

That is very true and I recommend that you consider what that means.

Bonding the grounded conductor to a the enclosure ensures that the grounded conductor and the enclosure are at the same potential, and provides a effective fault current path.

It is important and required to have a effective fault current path, a meter enclosure already has the best one it can have, a direct fault path back to the source.

You do not have to bond what is already bonded.

Do you use SE cable in your area?

We do and we do not run a bond wire along beside it.

Please take the time to draw what you are suggesting.


The bond wire you want will be a parallel neutral conductor and will cause more harm then good.

Trust me, Don and Roger, this is not the first time this discussion has come up.

Bob

 

[david]

Re: BONDING

250.92 Services.
(A) Bonding of Services. The non?current-carrying metal parts of equipment indicated in 250.92(A)(1), (2), and (3) shall be effectively bonded together.

B) Method of Bonding at the Service. Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by one of the following methods:
(1) Bonding equipment to the grounded service conductor in a manner provided in 250.8

The only required bonding together of non-current caring metal service equipment is accomplished by bonding such equipment to the service neutral. When a contractor bonds the service equipment together in this manner and is written up a violation this is wrong and the inspector need to view 250.92 2002 NFPA 70

 

[johnsonl]

Re: BONDING

Neutral-to-Case Connections,
The Right and Wrong Way (06-25-01)
By Mike Holt, www.mikeholt.com

 

[caosesvida]

Re: BONDING

the meter is already bonded, at least the meters here are. If the meter has a ground fault it goes right to the transformer. Although I have seen a few meter pans with holes in them that didn't fault the transformer fuse. Wires do get loose over time especially aluminum, especially if they weren't tourqed properly. I have seen some wires that were installed ( as many of you have) that are 60 or 70 years old, they havn't fallen out, but may need a little snuggin up. If you install it right it will live longer than you will.

 

[rasmithircgov.com]

Re: BONDING

I believe this Art. applies 250.25(B) Grounded Conductor Brought to Service Equipment. Where an ac system operating at less than 1000 volts is grounded at any point, the grounded conductor(s) shall be run to each service disconnecting means and shall be bonded to each disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with 250.24(B)(1) through (B)(3). You are bonded already to the meter and with a main bonding jumper you are bonded in the panel.

 

[rasmithircgov.com]

Re: BONDING

250.94 is to insure conductivity to the equipment. You aren't parraleling anything. I believe what the code is doing by requiring the conduit to be bonded it to better maintain fault flow in the system of conduit and encloser to this point. The can is bonded by the grounded service entrance conductor The main is bonded to the Grounded service conductor by the main bonding jumper period.If you think about it the grounded service entrance conductor is just an extention of the center tap of the transformer. As fault current goes to the center windings, the grounded service entrance conductor ensures that is going to happen. And bonding the race way at the service ensures that any fault current at that locaton is going to the grounded service entrance conductor. and it is not reliing on the lock nuts to ensure this will happen.

 

[iwire]

Re: BONDING

Originally posted by rasmithircgov.com:
250.94 is to insure conductivity to the equipment. You aren't paralleling anything.

This thread was talking about a service with PVC raceway between the meter enclosure and the panel.

If you add a bonding conductor between the meter enclosure and the panel you are most certainly paralleling the neutral (or MGN actually).

Think about it this neutral conductor is bonded to both enclosures, now you add a bonding conductor between the two enclosures.

That is a useless parallel path for neutral current.

 

[apauling]

Re: BONDING

New user. The only problems that I have with assuming that the neutral can be used as a bond in this case is that there is a difference of potential between the two metallic sections as the neutral is conducting current. The problems with using the neutral as bond might be clearer if it was assumed that the neutral was clad.

This is in miniature the same as bonding the neutral to the ground bar in a sub panel. A difference of potential exists between the disconnect which is theoretically tied to earth and grounded/bonded to all available systems, and the meter/mast which is only connected to the neutral conductor.

It may seem to be parallel, but the error is in using the neutral as bond. The two metal enclosures need to be bonded with a non-current carrying conductor/grounding conductor, not grounDED conductor.

imho, paul

 

[iwire]

Re: BONDING

Paul, Welcome , I see this is your first post.

The thread you have jumped in on (and you are more than welcome to jump in anywhere ) happens to be a long and hard to follow thread.

But in short when you have PVC or SE cable between the meter enclosure and the service panel, no additional bonding is required and a bond wire may present additional problems.

The NEC specifically allows using the grounded conductor (neutral) for bonding service equipment.

250.92(B) Method of Bonding at the Service. Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by one of the following methods:

(1)Bonding equipment to the grounded service conductor in a manner provided in 250.8

Also we could look at

250.142 Use of Grounded Circuit Conductor for Grounding Equipment.

(A) Supply-Side Equipment. A grounded circuit conductor shall be permitted to ground non?current-carrying metal parts of equipment, raceways, and other enclosures at any of the following locations:

(1)On the supply side or within the enclosure of the ac service-disconnecting means

The meter sockets (at least the ones we get in this area) have the neutral conductor terminal firmly bonded to the enclosure.

The Service panel enclosure will of course be bonded to the neutral as required by code.

Any attempt to add a bonding conductor between two enclosures that are already bonded to the neutral only creates a second path for neutral current.

Bob

[ March 31, 2004, 04:51 AM: Message edited by: iwire ]

 

[apauling]

Re: BONDING

I know it is legal but I always found it worrisome for stated reasons. The bonding conductor is the same as a ground run with neutrals, merely because a bare grounding/bonding conductor is run with conductors does not make it a parallel conductor.

I still see the safer install as bonding the two enclosures and not using the grounded conductor as the bond. I also dislike the idea of joining metal enclosures with non-metallic means.

paul

 

[bennie]

Re: BONDING

Remember that the supply side, of a service, is the most difficult part for clearing a ground fault. Most faults will burn clear before activating a primary cut out.

The safest system is to not have any metal raceways before the service overcurrent device(s).

It is unfortunate that meters are ahead of the main service switch and overcurrent device.

 

[roger]

Re: BONDING

Paul,

The bonding conductor is the same as a ground run with neutrals,

before the "Service Equipment" the "Grounded Conductor" is both the "Neutral" and the "Equipment Grounding Conductor".

merely because a bare grounding/bonding conductor is run with conductors does not make it a parallel conductor.

Paul, please explain how it will not be in parallel if "two" conductors are connected at the same point at "two" ends, remember we are talking about "Service Equipment".

Do you require Neutral and Grounding seperation at the first Main?

Roger

 

[apauling]

Re: BONDING

99 NEC 250-102 C, Equipment Bonding Jumper on Supply side of Service (ahead of disconnect)

yadayada "...the equipment bonding jumper, where routed with the raceways or cables, shall be run in parallel." Although the condition stated is not exact, it is obvious that here the grounding/bonding conductor is NOT considered a paralleled neutral although it is run in parallel with the neutral service conductor (s). There is no exception stated here for the "bonding jumper" to be disallowed where the neutral is in any form of electrical contact with the service equipment.

It is still my opinion that discontinuous metal conduit/raceways at the service entrance need to be bonded. The conductor that is run to accomplish this is the bonding conductor and is allowed to run in parallel with the other conductors. Merely because it is run in parallel with the neutral of the service entrance conductors, the bond is not a paralleled neutral.

I can see that this topic is contentious and that the opinions are entrenched. It is my reading of the code. What has been said so far does not dissuade me from that opinion. I do not expect that my opinion will sway other opinions. BUT still learning.

paul

 

[iwire]

Re: BONDING

Paul your only reading what you want to see, :roll: here is your statement.

Originally posted by apauling:
99 NEC 250-102 C, Equipment Bonding Jumper on Supply side of Service (ahead of disconnect)

yadayada "...the equipment bonding jumper, where routed with the raceways or cables, shall be run in parallel."

Here is the same NEC article word for word.

Part of 1999 250.102(C)

Where the service-entrance conductors are paralleled in two or more raceways or cables, the equipment bonding jumper, where routed with the raceways or cables, shall be run in parallel.

Notice this section is addressing paralleled service conductors and says "where routed".

What it is telling us is that if the service conductors are in parallel and if a bonding conductor is installed, that the bonding conductor will be run in each raceway in parallel with itself.

This the same idea as when ruining equipment grounding conductors in parallel feeder raceways.

This article is in no way telling us to install a bonding jumper in parallel with the neutral.

As a matter of fact to do so is a direct violation of 1999 310-4. Conductors in Parallel.

Please think about this for a 100 amp service.

The neutral conductor could be a 3 AWG copper, the bonding conductor would be a 8 AWG copper.

If we do what you are asking, run the 8 AWG from the meter enclosure to the service panel enclosure this 8 AWG is now electrically parallel with the 3 AWG neutral between the meter and the panel.

Now please explain how that is not a direct violation of 310-4?

I also have another question, what do you think this 8 AWG is doing for us?

If there is a fault in the meter can what path do you expect the fault current to take?

1)Back to the service panel?

2)To the grounding electrodes?

3)Back to the POCO transformer?

Originally posted by apauling:
Although the condition stated is not exact, it is obvious that here the grounding/bonding conductor is NOT considered a paralleled neutral although it is run in parallel with the neutral service conductor (s).

Paul, where in the article you cited does it even mention the neutral?

It actually says "bonding jumper, where routed" as in if routed.

Originally posted by apauling:
There is no exception stated here for the "bonding jumper" to be disallowed where the neutral is in any form of electrical contact with the service equipment.

Your right, there is no exception, as the code does not specifically require a bonding jumper on every piece of service equipment.

The code does require the service equipment to be bonded, but gives us options on how to accomplish this.

This section from 1999 could not be clearer that bonding jumpers are just one of the ways that bonding can be accomplished.

250-94. Method of Bonding at the Service

Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by one of the following methods:

1. Bonding equipment to the grounded service conductor in a manner provided in Section 250-8

2. Connections utilizing threaded couplings or threaded bosses on enclosures where made up wrenchtight

3. Threadless couplings and connectors where made up tight for metal raceways and metal-clad cables

4. Other approved devices, such as bonding-type locknuts and bushings

Bonding jumpers meeting the other requirements of this article shall be used around concentric or eccentric knockouts that are punched or otherwise formed so as to impair the electrical connection to ground. Standard locknuts or bushings shall not be the sole means for the bonding required by this section.

Paul you say your an inspector, that is great, but please remember while you are inspecting it has little to do with what you like or do not like, it is what the NEC says that matters.

The NEC does not always require bonding jumpers.

If you inspect a service with SE cable do you expect a bonding wire tie wrapped along the side of it?

Sorry for the long post, Bob

[ April 01, 2004, 04:37 AM: Message edited by: iwire ]

 

[roger]

Re: BONDING

Paul, (as a foot note to Bob's post) being that you are an inspector, I would think you would instinctively read the code article you are researching word for word.

It almost sounds as though you are trying to defend a "I've always done it this way" method.

Roger

[ April 01, 2004, 07:58 AM: Message edited by: roger ]