Proper grounding in a 2-family service

[PowerSupportElec]

The power company doesn't allow grounding in the meter pans.

The service I am installing:

2" mast with 4/0 Al SECs
2 gang meter pan
2 individual nipples run inside to 2 100A main breaker panels
water pipe and 2 ground rods will be used for electrodes

How do I ground/bond these 2 panels?

What I plan on doing is running the #4 from the water pipe and the #6 from the ground rods into 1 panel, then running a #4 jumper from that panel to the other panel. That should be compliant, correct?

Also, I could run #2 AL from each meter to each 100A panel since it's carrying the load of the entire apartment, correct?

 

[Dennis Alwon]

I agree with both however what is the calculated load. IMO the mast conductors must be size by 310.15(B)(16)

 

[PowerSupportElec]

I didn't realize that. It's a gas house so it's way under 180 Amps anyway.

 

[mbrooke]

Around here the norm tends to be 4/0 to #2 for a 100amp duplex, but use that as an example. I have to agree with Dennis on this one use table 310.

Im not fully aware of what code article forbids it but the jumper from the panel with grounds to the one without anything doesnt sound kosher. (I could be wrong, but its not something Im used to seeing)


Does each duplex have its own water pipe?

 

[PowerSupportElec]

Around here the norm tends to be 4/0 to #2 for a 100amp duplex, but use that as an example. I have to agree with Dennis on this one use table 310.

Im not fully aware of what code article forbids it but the jumper from the panel with grounds to the one without anything doesnt sound kosher.


Does each duplex have its own water pipe?

It's not a duplex, it's a 2 family house (1st floor apartment and 2nd floor apartment). Only 1 water main that splits into 2 meters.

If the jumper doesn't sound right, how would you wire it?

 

[texie]

It's not a duplex, it's a 2 family house (1st floor apartment and 2nd floor apartment). Only 1 water main that splits into 2 meters.

If the jumper doesn't sound right, how would you wire it?

Since you can't connect the GEC at the central point of the meter due to POCO rules you can connect each disco GEC to a common GEC using irreversible connectors. Off the top of my head I think you could also run GEC's from each disco to the GE separately. I do not believe that chaining from one disc to the other is compliant.

 

[mbrooke]

The way I would do it (as is the norm around here) is to run a number 6 from one panel, loop it through one ground rod, then the 2nd ground rod and then back inside to the second panel continously without bolts or crimps.


For your cold water bond run a continuous #4 from your pipe bond to the first panel and from the second panel run another number #4 to an irreversible crimp attached to the #4 going into the first panel.

 

[infinity]

I would run a GEC to the water pipe (sized for the SEC's to the meter enclosure) and tap off a bonding jumper to each panel with a split bolt (sized to the SEC's feeding each panel).

 

[PowerSupportElec]

A non-irreversible connection would be allowed because it's just a bonding jumper and not a GEC?

Where would the GEC end? It seems like you said to use a splitbolt for each panel, does that mean that the end of the GEC will just terminate into thin air instead of going into the second panel?

 

[kwired]

A non-irreversible connection would be allowed because it's just a bonding jumper and not a GEC?

Where would the GEC end? It seems like you said to use a splitbolt for each panel, does that mean that the end of the GEC will just terminate into thin air instead of going into the second panel?

If you run GEC all the way to one of the panels you eliminate the need for a second tap device, but have a larger conductor in one panel than needed if you ran taps to both panels.

Only the GEC needs irreversible connectors, your bonding jumpers to other electrodes could use non-irreversible types of connectors.

 

[PowerSupportElec]

If you run GEC all the way to one of the panels you eliminate the need for a second tap device, but have a larger conductor in one panel than needed if you ran taps to both panels.

Only the GEC needs irreversible connectors, your bonding jumpers to other electrodes could use non-irreversible types of connectors.

Gotcha, makes sense now.