Metering a 120/208v 3 wire service

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dwall said:
How accurate is a 240v 3wire Meter on a 120/208v service
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From what I have seen, utilities use the same meter for 120/208 3W as they do for 120/240 3W. They measure the current in each leg and the voltage line-line.
 
jim dungar said:
From what I have seen, utilities use the same meter for 120/208 3W as they do for 120/240 3W. They measure the current in each leg and the voltage line-line.
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I knew that they used 'non-blondel' compliant meters for 120/240 service, but it is strange that they would do this for 120/208 service, given how much such a meter would underbill.

-Jon
 
However, to answer the original question:

Common 120/240V meters work as Jim described, and assume that the line-line voltage is in phase with the line-neutral voltage, and that the line-line voltage is evenly divided between the two line-neutral voltages. This assumption is not theoretically correct, but is apparently close enough for billing purposes on 120/240V services.

If you assume a _perfect_ version of such a meter, then on a 120/208 service, all _line-line_ loads would be billed accurately, but line-neutral loads would be significantly underbilled.

I belive that line-neutral loads would be metered at 75% of true value.

-Jon
 
In today's world of electronic meters, most all of us utilities use a meter that can register either 120/208 or 120/240 single phase with no problem.
 
and with most of the POCO's specs on 208v 1? networks they useally ask for 5 th jaw on the metering unit [ most will be at 9'o clock location some used 6 oClock location ]

unless you got one of dangbat fanged AMR which it will automatically read the voltage and set it propely.

Merci,Marc
 
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