Multiple grounds, 1 H20...

Status
Not open for further replies.

celtic

Senior Member
Location
NJ
I have a "situation" where I am swapping out 1 3? 200A MCB in a strip mall. The other 2 stores are 1? 200A MCB panels. There is one water meter serving all three locations.

Can I use ONE #6(T250.122) to jump the meter:
a) then multiple clamps to attach these other conductors
b) then use a block to attach the 4 conductors to
c) use a section of bus to attach all four.
d) bug the addition conductors to the clamped #6
e) something I haven't accounted for

The "interesting" part is, the water meter is UNDER a sink in the cavity in the floor ....and there is some sort of miniture water heater over that cavity ....so friggin' tight, a picture would be pointless. BTW, that costs extra :D
 
celtic said:
Bump...

Anyone want to take a stab at it?
Sure I will. You're talking about EGC's judging from the wire size & code section, right? Then I say do what you propose. I say that cuz I can't find anything vote no on in the code. Now the beauty of me being wrong, if I am, is that someone will correct me & set you on the right path. Good luck.
 
water

water

I'll bite........

assumptions...all panels are service panels.

I would think that you would need to base the meter "jumper" on the sum of the service conductors.. in this case that would probably require a 1/0.
(these are grounding elect cond NOT eq ground 250.66 rather that 250.122)

Unless you and the AHJ consider the exception to 250.52 to be applicable, the connections from each panel would need to be within 5 ft of the water service enters the building. If we allow the exception, you could "hit" the piping as close as practical from each service panel.

my opinion
 
Are the panels Service - supplied from the utility company, or are they supplied from a disconnect and on the load side of the service disconnecting means?

So many guys will install a panel and meter on the load side of a service disconnecting means and ground it as it were a service, when in fact it is a feeder.
 
rcarroll said:
Now the beauty of me being wrong, if I am, is that someone will correct me & set you on the right path. Good luck.

I follow that logic all the time here :)
It's a great policy LOL.
 
It's a crazy set-up ...here's some more info:
2 of the 3 services come from underground ...1 is over head ...
There is no "common" disconnect - each store has it's own MCB panel.
Each service may very well be a seperate(OH/UG) lateral back to a Poco pole/vault .
ALL use the one water service and water meter.
 
Pierre C Belarge said:
So many guys will install a panel and meter on the load side of a service disconnecting means and ground it as it were a service, when in fact it is a feeder.

Good point ...
Think I'll have pay the location another visit ....BUT...none of the stores has a basement, so it'll be more of a drive-by than anything.
 
augie47 said:
I would think that you would need to base the meter "jumper" on the sum of the service conductors.. in this case that would probably require a 1/0.
(these are grounding elect cond NOT eq ground 250.66 rather that 250.122)
Good catch...you are absolutely correct on the 250.66...if I use one common jumper a 1/0 may fit the bill.


augie47 said:
Unless you and the AHJ consider the exception to 250.52 to be applicable, the connections from each panel would need to be within 5 ft of the water service enters the building. If we allow the exception, you could "hit" the piping as close as practical from each service panel.
"...where conditions of maintenance and supervision ensure that only qualified persons service the installation, ..."

I don't think that's part of the equation:
070307_1238.jpg


070307_1238a.jpg



Directly to the LEFT is the stores front window.
Directly IN FRONT of this mess is a booth (it's a diner)
The panel/meter is hidden by a sliding door.
 
ground

ground

"...where conditions of maintenance and supervision ensure that only qualified persons service the installation, ..."

from the pics, I'd say you are certainly correct on the "qualified maintenance"...

So 250.52 exception is out; 250.58 requires common electrode(s); since we have "metalic path" 250.104 (A) 2 doesn't help us.


If you have effectiovely grounded building steel, you could connect to steel at each panel, then steel to water.

250.64 (D) would allow you to "tap" to a common electrode conductor which might help you some.
 
augie47 said:
If you have effectiovely grounded building steel, you could connect to steel at each panel, then steel to water.

250.64 (D) would allow you to "tap" to a common electrode conductor which might help you some.

No steel ...wood frame on red brick foundation.
 
water

water

leaning more and more to a grounding electrode conductor from each service panel to the common water pipe within 5 ' of pipe's entrance and a jumper around the meter, back-flow devioce etc.
 
augie47 said:
leaning more and more to a grounding electrode conductor from each service panel to the common water pipe within 5 ' of pipe's entrance and a jumper around the meter, back-flow devioce etc.

The way I saw what little was to be seen, that's the way i was headed also.

BUT ....there is precious few inches (and that's being generous) to attach clamps. I was hoping to have one jumper around the meter and then "tap" that using a polaris or bugs ...but I don't know if it's legal?
 
taps

taps

as long as the run to the pipe is sized per the added service conductors and you tap and not splice, I see no problem.
Form experience I'd probably use split bolts, but the right polaris would work.
 
augie47 said:
as long as the run to the pipe is sized per the added service conductors and you tap and not splice, I see no problem.
Form experience I'd probably use split bolts, but the right polaris would work.

It's just a basic panel swap...200A FPE to 200A QO ...ONE unit ONLY.

The thought behing the polaris is room ...I literally have to remove a bathroom sink to get to the meter:mad:

I cannot even say with 100% certainty that the grounding is an issue - but I'd rather give the customer a higher price based on the "what if's?" and accept less (if grounding is ok) at the end (to be fair).
One thing I hate is to have to bump the price up because "we didn't know."


IF by some odd chance I need to add ground rods....would these be at #6 ???? I have #6 in my head...can't seem find the reference...
 
Any chance you have an exterior connection point for the water line if it is also 10' or more in direct contact with the soil? You'd still have to jumper that water meter, but you don't need the 5' stuff if you are connecting to your water pipe electrode on the exterior of the building. 250.52
 
Status
Not open for further replies.
Top