How To Grounding And Bonding A 100 Amp Service Panel

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grounding and bonding with subpanels

• Thread starter alpinemike
• Beginning date Nov ii, 2005

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• #i

This is a 50 yr old resisence with the service (200 amp)on an outside pole.In that location is a distribution panel with a breaker that feeds a main panel in the business firm via 2" pvc, with no bonding wire in the pipe.At that place is a #half-dozen ground wire to a ground rod. The footing wire is landed on the dist. console neutral, not the meter neutral. The principal business firm panel feeds a 100 amp sub console via 4-three romex. We installed that panel and put a split basis bar in it. The neutal bar in the inside main panel has a #vi ground taken to the water pipe. When I take the wire off the water pipage , the resistance between neutral and ground goes to megohm. The wire into the house is one-time rubber coated stuff and would exist impractical if not impossible to repull with a bond wire. I know the lawmaking says you accept to continue the ground and neutral separate past the main console. Anyhow out of this mess, almost as I can tell everything is ok like it is (there is no inspection in this area). Please review the code for bonding and grounding with sub panels involved. Thank you to all you lot gurus in accelerate

• #two

Re: grounding and bonding with subpanels

Your problem is that at the master panel in the firm there is no footing/neutral connexion. If you have no metal paths between the exterior pole and the house panel you may use the provisions of 250.32 which volition allow yous to bond the neutral and ground at the main console and keep your 3 wire feeder. You said that your 2nd panel was 100 amps fed with 4-3 NM cable. My concern is that y'all should have used a 70 amp or smaller OCPD for this feeder since 4-3 NM has an ampacity of 70 amps.

• #3

Re: grounding and bonding with subpanels

Thanks infinity, brain f**t on my role with the no.2, there is a 70amp breaker right there. I remember 250.32 describes my situation, thanks again.

• #4

Re: grounding and bonding with subpanels

Am I reading this right: 200A service on pole, 200A main panel on house fed with 3 wires from the pole service, 100A subpanel in house fed from business firm main panel with 4-iii NM cable.

If then, then I meet some issues:
1. The subpanel must be fed with 4 wires and not three (unless you lot but want a 120V panel). Only feeders to discrete structures can use the 3 wire method.
two. The #6 to the water pipe is also modest. This must be sized per 250.66 and would need to exist #four for a typical 200A service.
3. Where is the ground rod? You must accept ii at the firm connected to the neutral autobus in the house master panel. Y'all may (not sure) also need 1 at the pole connected to either the distribution panel neutral or the meter neutral.
four. Your nearly disquisitional problem is the lack of neutral-footing bail. Where were you measuring between the neutral and ground when the resistance went to infinity? If this was at the subpanel bus bars, then infinity has information technology right -- no neutral/ground bonding screw installed at the house main console. You exercise need to install that since you but have a three wire feed to the firm.

• #five

Re: grounding and bonding with subpanels

i. The subpanel must be fed with 4 wires and non three (unless y'all merely desire a 120V panel). But feeders to detached structures can employ the 3 wire method.

I would disagree. If in that location are no metallic paths between the strucutres (the distribution panel and the firm panel) than 250.32(B)(2) would employ.

(2) Grounded Usher. Where (1) an equipment grounding conductor is not run with the supply to the building or construction, (two) at that place are no continuous metallic paths bonded to the grounding organization in each building or structure involved, and (three) ground-fault protection of equipment has not been installed on the supply side of the feeder(south), the grounded conductor run with the supply to the edifice or structure shall be continued to the building or structure disconnecting means and to the grounding electrode(south) and shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded.

• #6

Re: grounding and bonding with subpanels

Miscommunication is the devil, Bobby!

Alpinemike wrote:
The basis wire is landed on the dist. panel neutral, not the meter neutral.

That'southward legal. The meter isn't the service disconnecting means, the panel is. (250.24)

There is a distribution panel with a breaker that feeds a chief panel in the house via two" pvc, with no bonding wire in the pipe.

This is where it's getting fuzzy Mike. I encounter:

1. 200 Amp Service on a pole.

2. 200 Panel on a pole (peradventure the same affair).

3. 2" PVC from this pole-panel to interior of the firm's main panel. Violation of 225.31-ish, the disconnecting means for a remote structure must be outside or within nearest the entrance of conductors. At that place is no EGC, which if at that place are no other metallic paths, is legal. What size conductors are in this pipage? What size breaker?

4. Chief Panel in Firm. There is a #6 footing wire to the h2o pipe. Depending on the size of conductors, this could be legal or not. Mike never specified that this panel was fed with conductors big plenty for 200A. I'thousand thinking there could be other circuits from the outside pole panel, and the house is less than 200A.

The neutal bar in the within main console has a #six ground taken to the water piping. When I accept the wire off the water pipe , the resistance between neutral and ground goes to megohm.

You have an EGC somewhere in the business firm touching the water pipe. That'southward legal. The reason things are behaving that manner is because the water pipe was landed on the neutral bar of the panel.

When everything was hooked upwards, juice in your meter was leaving the red probe, travelling through the EGC'southward until it reached water heater, or any was making contact with the water pipe. So it was travelling back along the GEC to the neutral bar of the panel where information technology was landed. And so you had continuity between neutral and ground until you removed the electrode conductor, breaking the circuit.

Install an appropriate bonding jumper betwixt the neutral and grounding bar of this primary panel. Reinstall the GEC, and supplement information technology with a ground rod.

5.

The principal house panel feeds a 100 amp sub panel via 4-three romex . Nosotros installed that console and put a separate ground bar in it.

Is this new or erstwhile romex? Is in that location a EGC with it? The water pipe is not in this panel, is it?

From this point in your post, you went a fiddling chaotic, so I am really confused.

Tin you write out a "one-line diagram", filling in the gaps? When y'all hop back and forth, it makes information technology incommunicable for us to make sense enough to help you.

[ Nov 05, 2005, 08:19 AM: Message edited past: georgestolz ]

• #7

Re: grounding and bonding with subpanels

Originally posted by infinity:
I would disagree. If there are no metallic paths betwixt the strucutres (the distribution console and the house panel) than 250.32(B)(2) would apply.

What is non clear in the posters question is whether the 100A subpanel is inside the same structure as the primary house console, or a dissever detached construction.

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Source: https://forums.mikeholt.com/threads/grounding-and-bonding-with-subpanels.12468/

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