5th jaw

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My feeling is... Something to measure against, as opposed to in relationship to. Multi wire loads are combinations - not 'each' phase, 5th's and 7th's don't go though the meter.

edit: one too many 'o's in the word 'to'.
 
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The 5 th jaw is very typical when you run off the 3 ph network to single phase metering [ this is common with 120/208 volts system ]

one good example you will find this with 5th jaw is apartment complex where they have multi metering devices if the power supply 3 phase incomming and single phase outgoing so they used the 5 th jaw to read the line to netrual voltage on both coils


http://www.themeterguy.com/Theory/meter_connections.htm


this link will show the metering connections there i hope it will help to expain more clear on this one

Merci , Marc
 
Pierre C Belarge said:
It also keeps the meter from being turned upside down and having the customer stealing electricity.:D
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I believe that you have the correct answer. The old 4 wire meters could be turned upside down and they would run back wards.
 
The fith leg is for a single phase 120/208 service or it can be used to control hot water heater on a 240 volt resedential service.
 
newt said:
The fith leg is for a single phase 120/208 service or it can be used to control hot water heater on a 240 volt resedential service.
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I have a 5 jaw meter on my own home and it has none of the conditions you describe.
 
The 5th terminal is used in some meters to provide 120 volt power to the balance elements internal to the meter.

5thterminals-base.jpg
 
I work as a meter tech for a utility and the only time we use a 5th leg is for the120/208 service if you did not ground 5th leg you would have 104v on each coil in the meter not 120v loosing revenue. The other style meter in our area is for the night rate meter,at 11:30 the 5th leg is energized so it will heat your water on the cheaper rate. Is your meter a form 2, 240 or a form 12 which has a 120v coil?
 
newt said:
Is your meter a form 2, 240 or a form 12 which has a 120v coil?
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Good question, where would we find this information? Is it visible on the front of the meter.
 
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