Grounding Conductors in paralell raceways

[mon305]

Can I run seven sets of 500kcmil copper wires in paralell with just one equipment grounding conductor?

 

[iwire]

Re: Grounding Conductors in paralell raceways

No, you must run a ground conductor in each raceway fully sized to the overcurrent device.

250.122(F)

That is if you choose to run one at all.

[ December 16, 2003, 04:56 PM: Message edited by: iwire ]

 

[mon305]

Re: Grounding Conductors in paralell raceways

Well I don't know what to say because in my job I have been told to run seven sets of 500kcmil with one 350kcmil grounding conductor

 

[dereckbc]

Re: Grounding Conductors in paralell raceways

mon305, the minimum EGC is based on 250.122 if you choose to use one or the OCPD size. If the raceway meets 250.118 you do not have to run one. I would run an EGC no matter what raceway is used.

If you are increasing the size of the ungrounded conductors for any reason. you are required to increase the EGC.

 

[iwire]

Re: Grounding Conductors in paralell raceways

First off welcome to Mikes forum.

It sounds like a 2500 amp feeder, unless you have voltage drop issues.

All I can say is show whoever is telling you this the code section.

250.122(F) Conductors in Parallel. Where conductors are run in parallel in multiple raceways or cables as permitted in 310.4, the equipment grounding conductors, where used, shall be run in parallel in each raceway or cable. One of the methods in 250.122(F)(1) or (2) shall be used to ensure the equipment grounding conductors are protected.

(1) Each parallel equipment grounding conductor shall be sized on the basis of the ampere rating of the overcurrent device protecting the circuit conductors in the raceway or cable in accordance with Table 250.122.

(2) Where ground-fault protection of equipment is installed, each parallel equipment grounding conductor in a multiconductor cable shall be permitted to be sized in accordance with Table 250.122 on the basis of the trip rating of the ground-fault protection where the following conditions are met:

(1) Conditions of maintenance and supervision ensure that only qualified persons will service the installation.

(2) The ground-fault protection equipment is set to trip at not more than the ampacity of a single ungrounded conductor of one of the cables in parallel.

(3) The ground-fault protection is listed for the purpose.

[ December 16, 2003, 05:26 PM: Message edited by: iwire ]

 

[mon305]

Re: Grounding Conductors in paralell raceways

thank you. I agree with you but the conductors are coming out of a transformer to a service disconect and I am running a neutral conductor in each pipe and they are bonded together with the grounding conductor inside the transformer.Thank you

 

[iwire]

Re: Grounding Conductors in paralell raceways

Originally posted by mon305:
the conductors are coming out of a transformer to a service disconect and I am running a neutral conductor in each pipe and they are bonded together with the grounding conductor inside the transformer.Thank you

Huh?

I am not sure I am following you, this is a service?

Is this grounding conductor bonded at both ends?

 

[websparky]

Re: Grounding Conductors in paralell raceways

Let me see if I have this right.

Pad mounted transformer.
Service disconnect.
The conductors between these two points are;
1. phase conductors (3 x 7)
2. Grounded conductor from transformer's XO and connected to a GEC and a GE.(x 7)
3. No other conductors required to the service disconnect.

Right?

[ December 16, 2003, 05:59 PM: Message edited by: websparky ]

 

[mon305]

Re: Grounding Conductors in paralell raceways

I am sorry, my mistake.What I'm trying to say is that the neutral conductors are bonded together with the grounding electrode conductor inside the transformer.The transformer is fed from a main switch and the secondary is feeding a main breaker in a distribution panel.Now,my question is,do I really need one grounding conductor in each pipe even when I have a neutral in each pipe that is bonded to the GEC in the transformer

 

[mon305]

Re: Grounding Conductors in paralell raceways

What I think is that there must be some kind of specifications in my job that I don't know because they told me to do it that way

 

[websparky]

Re: Grounding Conductors in paralell raceways

Engineers and/or system designers can and do specify certain elements that may be above the code required minimum.

This in of it's self is not a problem.

However, we all need to check the specifications and be sure they are at a minimum of code compliance.

The question that now arises is, where is the GEC connected and is there a GE?

 

[mon305]

Re: Grounding Conductors in paralell raceways

The GEC is conected in the transformer,in the main switch and to the steel of the building,wich in this case is the GE, websparky.

 

[mon305]

Re: Grounding Conductors in paralell raceways

Thank you very much for your cooperation

 

[websparky]

Re: Grounding Conductors in paralell raceways

You are welcome!

 

[don_resqcapt19]

Re: Grounding Conductors in paralell raceways

You can't use both a grounding conductor and a grounded conductor between the transformer and the service disconnet. The grounding conductor would be connected in parallel with the grounded conductor creating a violation of 310.4.
Don

 

[tom baker]

Re: Grounding Conductors in paralell raceways

Our POCO won't allow an equipment ground in a raceway to a pad mount transformer.