240v meter for 120v RV power post

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Bhakta

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Alachua County, FL
During my lay-off period, I decided to finally hook up my RV outside my home. One of the kids will stay in it while we are not traveling. I want to monitor the power use.

I have run the required 120v 30a circuit from my panel to the RV power post.

Now, all I have is an old Schlumberger 240v watt hour meter.
I terminated the ungrounded line and load to the proper jaw terminals. The neutral bypasses the meter. (This leaves an entire leg's jaws unused). I pushed the meter into the jaws and energized the RV circuit. Everything in the RV operates as normal, but the meter disc/dials do not spin. I hesitate to "experiment" anymore.

I guess I am too embarrassed to face my peers with the question:
How do I properly monitor the 120v RV circuit with a 240v meter? I know there is a way... Can I simply splice the line side and load side, so that each "leg" would run parallel through the meter?

This was not covered in my JATC curriculum.

Anyhow, the meter's specs:
Schlumberger
240v 3w
CL200
Type J5S 30TA
23988020 (model#?)
FM@S 60Hz

Thank you for your time.
 
There are a couple of these installed on our system now. I actually hate this connection because it requires us to remove the link in the back of the meter and wire it to the neutral. The meter you have is more than likely a form 2S meter. What you truly need is a form1S.
That being said, in order for the meter disk to spin, it needs exactly what any device needs, supply and return. You have the supply, just no return as far as the meter is concerned. You can make the disk spin by simply running a neutral wire to the unused jaws.

In order to ACCURATELY meter this load, you must remove the test link on the back of the meter and ground the meter with the little screw.

Here is a couple of diagrams that will show you how to do this. I have a suggestion, remove the 30 amp breaker and install a 15 amp breaker until you have connected the meter and tested it. Even better would be a small current limiting fuse wired in line until you are done. Connecting the ground to the wrong side of the test link will draw an arc.

You will be connecting neutral to one side of a transformer is essentially what you will have to do. Connecting the ground to the energized side of the transformer will have the expected results.


http://www.uomschool.org/Meter_Book... Drawings/2S - 120 2W Single Phase - alt1.pdf


http://lib.store.yahoo.net/lib/eofcorp-store/240V.pdf
 
Hv&Lv said:
There are a couple of these installed on our system now. I actually hate this connection because it requires us to remove the link in the back of the meter and wire it to the neutral. The meter you have is more than likely a form 2S meter. What you truly need is a form1S.
That being said, in order for the meter disk to spin, it needs exactly what any device needs, supply and return. You have the supply, just no return as far as the meter is concerned. You can make the disk spin by simply running a neutral wire to the unused jaws.

In order to ACCURATELY meter this load, you must remove the test link on the back of the meter and ground the meter with the little screw.

Here is a couple of diagrams that will show you how to do this. I have a suggestion, remove the 30 amp breaker and install a 15 amp breaker until you have connected the meter and tested it. Even better would be a small current limiting fuse wired in line until you are done. Connecting the ground to the wrong side of the test link will draw an arc.

You will be connecting neutral to one side of a transformer is essentially what you will have to do. Connecting the ground to the energized side of the transformer will have the expected results.


http://www.uomschool.org/Meter_Book... Drawings/2S - 120 2W Single Phase - alt1.pdf


http://lib.store.yahoo.net/lib/eofcorp-store/240V.pdf
Click to expand...

I forgot to add, I assumed it was a form 2S (FM2S) because the @ is above the 2 :D
 
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