Re: OT: Electrical Grounding

Posted by John T on February 13, 2010 at 12:40:41 from (71.55.31.109):

In Reply to: OT: Electrical Grounding posted by regularguy on February 13, 2010 at 10:53:18:

Regular guy, Its been yearsssssss since I was a secondary power distribution engineer so Im a bit rusty on the latest code, that being said however, here are my thoughts.

I was taught and designed PER THE PRINCIPLE OF "SINGLE POINT GROUNDING". One problem is different jurisdictions and utilities may do things differently SO CONSULT WITH YOUR LOCAL AUTHORITY AS TO HOW THEY DO THINGS (i.e. do they bond Neutral to earth in the meter base or main panel???) AND DO AS THEY SAY NONE OF US HERE LOL

Sooooooo if the local authority bonds the Neutral to mother earth (via a No 4 copper grounding electrode conductor to a grounding electrode such as driven rod or rods and/or metal pipes etc) IN THE METER BASE, then I would carry 4 wires to the Main panel (2 Hots, Neutral, Equipment ground) AND ISOLATE/SEPERATE the Neutral and Equipment ground buss bars in the Main panel. Of course the grounding screw would bond the panels metallic frame to the equipment ground buss.

HOWEVER if your local authority DOES NOT bond Neutral to earth in the meter base, then Id only carry 3 wires from base to panel (2 hots and Neutral) (the No 4 copper grounding electrode conductor can still carry through to get to the main panel of course, just not tied to Neutral in the base) and inside I would bond the Neutral Buss and Equipment Ground busses together and the No 4 copper grounding electrode conductor would bond to the Neutral.

BUTTTTTTTTTTTTTTTTT if your local authority says bond Neutral to earth (via that No 4 copper grounding electrode conductor) in the meter base AND bond Neutral buss to Equipment ground buss in the panel THEN I GUESS YOURE BOUND BY WHAT THEY TELL YOU so go by them NOT BY ANYONE HERE. That dont jive with my idea of single point grounding of the Neutral (like at base or panel but NOT both) but again Im rusty on the code not having designed for yearsssssssssssss

NOTE some panels have 2 seperate and isolated Neutral Buss and Equipment Ground Busses AND USE A big bar to bond them together when they are to be used as a SERVICE ENTRANCE. If they are used as a downstream sub panel, however, the tie bar is NOT used so they remain isolated.. Some panels (suitable for main service entrance ) only have one big common buss used for BOTH Neutrals and Grounds so they couldnt be used as a sub.

Hopefully other gents such as electricians and design engineers etc more code recent can add to this if I forgot anything or Im incorrect BUT I STILL FAVOR ONLY SINGLE POINT GROUNDING OF NEUTRAL TO THE GROUNDING ELECTRODE CONDUCTOR

Thats my story n Ima stickin to it till proven otherwise lol

Best wishes n God Bless Im headed to a cruise but will check back with yall late Sunday

Ol John T

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