Submetering 208V with 240V utility meter

[luckylerado]

I am setting up a temp power for a job trailer. Very low demand and very short term. I am required to meter my usage and pay accordingly. I have grabbed a 208V single phase branch circuit.

My question is if I install a typical residential meter enclosure and use a typical 120/240V meter that a utility would install will it work?

60 amp. Single phase.

 

[iwire]

No it would not work.

You need a five jaw meter with a neutral connection.

I believe this has to do with the phase angle between hots not being 180 degrees.

 

[GoldDigger]

It would be an approximation. The readings would be correct to the extent that there were only line to line loads.
Any balanced or unbalanced line to neutral loads would be metered as. if they were 104V loads with a low power factor.
The 120/240 residential meter does not have any connection to the neutral and assumes that the line to neutral voltage is half the line to line voltage and in phase with it. This is what iwire said, just in more detail.

 

[meternerd]

Yup, you need a Form 12S 120V meter to account for the different phase angle. The 12S (network) meter has a fifth jaw because it uses neutral for each 120V leg. A standard 4 jaw socket must have a "fifth jaw kit" installed for the meter to work. Available at most electrical supply houses.

 

[winnie]

My understanding matches GoldDigger's. This meter _approximates_ line-neutral loads as having line current * 1/2 line-line voltage. For single phase services, this is a pretty good approximation, for two legs of 3 phases, then the approximation is far wrong. _However_ if you have no line-neutral loads (only 208V loading) then the meter should be accurate.

-Jon