Bonding / Equipotential

[mfom]

Hello!

May I ask for your help? I am still a quite "young one" so there are tons of questions older and more experienced guys might know...

I am working on a site with another electrician who was called to do the underground feeder and meter pedestal at the pole.

Beside the pole (outdoors) he installed a meter socket and a fused disconnect switch. Here he bonded the Neutral to Ground with means of an adjacent 8' ground rod.

Then he ran 3 wires in SCH40 to the panelboard in the basement entering the building structure right beside the panelboard.

He asked me to seperate Grounds and Neutrals (ins. N-Bar)at the existing indoor panelboard and drive another ground rod at the house for the indoor panelboard (the way the wellpump is setup does not allow grounding there)

Since he is a superior (older and native)I did not express my doubts, but am I mistaken that:

A. You don't need a disconnect at the meter, since it is outdoors and the conductors enter right where the main panelboard is (IF YOU BURY IT DEEP ENOUGH, not even res. Driveway - plain garden)

B. If you don't need a disconnect, you don't need a ground rod out there, instead bonding N and G at the panelboard inside

C. If you have a disconnect, main panel becomes of course a subpanel, BUT THEN bonding is necessary with a bonding jumper (4th conductor)between disconnect and indoor panelboard, since we have a nonmetallic raceway (SCH40).

D. Anyway - shouldn't ALL groundrods, waterpipes, CATV, steel building structure, etc. be bonded together because of the equipotential (achieving the so called grounding system)?

Perhaps I am mad, I just don't understand it, or maybe it's because they still have the 1995 NEC here - is it a new approach since the NEC 2000?

When I cautiously asked, he said that the soil here has a really low resistance, and he didn't understand what I meant with equipotential.

So did I miss a point? I'd really like to know, so that I do it consciously the right way the next time.

Thanks for any replies!

 

[hurk27]

Re: Bonding / Equipotential

By mfom: Then he ran 3 wires in SCH40 to the panelboard in the basement entering the building structure right beside the panelboard.

He asked me to separate Grounds and Neutrals (ins. N-Bar)at the existing indoor panelboard and drive another ground rod at the house for the indoor panelboard (the way the wellpump is setup does not allow grounding there)

This is a setup for an electrocution !!!

Not running a Equipment grounding conductor or bonding the neutral at the house panel will cause all the grounding in this house and anything connected to it, to become energized in the event of a ground fault. The grounding electrode will do nothing to prevent this as the resistance of it is way too high to pass the fault current back to the neutral conductor at the first disconnect!!!
(120 volts divided by 25 ohm's = 4.8 amps that the ground rod can fault)

You must correct this at once or you, your co-worker, and the company you work for, could be held liable if someone were to be killed or injured by this.

There has been electrican's that have been charged with man slaughter for doing something very close to what you have done.

But as far as the disconnect goes I have seen it done both ways. But a ground rod at the meter should be needed as most inspectors would call a pole mounted service a structure. This would also require a disconnect at the house also as each structure requires a disconnect per: 230.70.
But a main breaker in the house panel would can serve as this disconnect.

As far as the fourth wire: Since you have a service on a pole that has no other metallic path's between this pole and the house you are allowed to just run 3 conductors But you must bond the neutral to the grounding at the house panel. AS allowed by 250.32(B)(2)

I will say again this must be corrected at once before anyone gets hurt !!!

[ November 10, 2004, 01:22 AM: Message edited by: hurk27 ]

 

[mfom]

Re: Bonding / Equipotential

Thank you Wayne!

Seems there was indeed something to doubt!! And I was flipping the code and going crazy to find an explanation for this kind of setup
The service is fortunately not yet connected, I declined to seperate N & G (told the owner I had to speak this through a bit more with the other electrician). Anyway, a UL Inspection is scheduled now and then I am not the one who has to expose that.
This town is really an adventure...