5th Jaw meter socket to submeter 208V loads

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Bert Sutcliffe

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Location
New Hampshire
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Electrician
I have been reading old threads trying to understand a POCO request for a fifth jaw socket here in NH. I installed two single phase 208V EV chargers at a hotel and ran 2 hots and a ground through a standard 4 jaw meter socket at the request of the POCO so they can submeter the charger use. The feeders terminate in a small outdoor panel and there is a separate breaker for each charger.

After I finished, they requested a fifth jaw for their meter. I explained there was no neutral and their response was to hook the jaw to the case of the meter - there would be no current flowing through the jaw - they just need a ground reference. I am understandably hesitant to hook anything up to the grounded conductor.

Does anyone know first if it would code compliant to tie the jaw to the case (and the EGC) and secondly if it is even necessary? I could get back into the EMT run and pull a neutral if it is necessary but I don't know how I would size it.
 
Bert Sutcliffe said:
I have been reading old threads trying to understand a POCO request for a fifth jaw socket here in NH. I installed two single phase 208V EV chargers at a hotel and ran 2 hots and a ground through a standard 4 jaw meter socket at the request of the POCO so they can submeter the charger use. The feeders terminate in a small outdoor panel and there is a separate breaker for each charger.

After I finished, they requested a fifth jaw for their meter. I explained there was no neutral and their response was to hook the jaw to the case of the meter - there would be no current flowing through the jaw - they just need a ground reference. I am understandably hesitant to hook anything up to the grounded conductor.

Does anyone know first if it would code compliant to tie the jaw to the case (and the EGC) and secondly if it is even necessary? I could get back into the EMT run and pull a neutral if it is necessary but I don't know how I would size it.
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It’s required to meter that load properly.
We require it also
Those two hots are 120° apart rather than 180° apart as they are in a 2S metering set up.
12S is what is required
 
The "ground"(your word) you ran thru the meter base to your panel would be a neutral and in most cases routed thru a grounding lug in the meter socket.
Is that not the case in your install ?
 
I figured I would post an answer to my own question in case someone runs into this problem in the future.

According to Honeywell technical support, the manufacturer of the meter to be set, a 2S meter will accurately read 208V (line to line) loads without a fifth jaw. The fifth jaw comes into play only on 120V loads and the current on the neutral (and fifth jaw) could be as high as the overcurrent device (100A in my case). They were concerned the accuracy would be compromised if any 120V loads were added in the future.

To confirm, I installed my own 12S meter, ran the chargers for a couple of weeks, and compared it to the digital readout on the charging stations. After 814 KWH, the readings were within 1%.
 
Bert Sutcliffe said:
I figured I would post an answer to my own question in case someone runs into this problem in the future.

According to Honeywell technical support, the manufacturer of the meter to be set, a 2S meter will accurately read 208V (line to line) loads without a fifth jaw. The fifth jaw comes into play only on 120V loads and the current on the neutral (and fifth jaw) could be as high as the overcurrent device (100A in my case). They were concerned the accuracy would be compromised if any 120V loads were added in the future.

To confirm, I installed my own 12S meter, ran the chargers for a couple of weeks, and compared it to the digital readout on the charging stations. After 814 KWH, the readings were within 1%.
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I disagree with part of that..
No offense meant, I just think you didn’t talk to the right people at Honeywell..

Topic: 2S in a Network (12S) service | Upper Midwest Metering Association

ummaonline.org ummaonline.org

Harris Institute of Technical Training - Open Forum - 2s Meter in a 120/208V service (12s application)

metergod.com metergod.com
 
electrofelon said:
So just to clarify Hv, what do you disagree with? The Honeywell person said the fifth jaw wasn't needed for line to line loads.
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The current on the neutral and fifth jaw. The fifth jaw will never see full neutral current.
 
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