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Home Q & A Board Science-Related Homework Help Physics
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RJ RJ
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Posts: 62
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11 years ago
There is three phase wiring running into a panel and I need to determine whether or not it is pulling 208 or 240 volts.  The three wire colors are black, red, and "blue" (taped).
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wrote...
#1
11 years ago
I recommend using a volt meter.
wrote...
#2
11 years ago
Well, should you not measure 208V from each wire to ground (or neutral), if it is present? Should you not also see 240V between any 2 of the 3 phase wires?
I don't get what you mean by Blue (taped). Does this mean it is not connected?
Or are you asking is the panel single or 3 phase? If that's it, I guess it would be 240V single phase, if the blue goes nowhere.
wrote...
#3
11 years ago
holy god in heaven! don't follow that second answer!  in the US three phase power systems are generally 208V from phase to phase and 120V from phase to neutral or ground.  single phase services such as the ones used in residential feeds are 120V phase to ground or neutral and 240V phase to phase.  it has to do with how many coils are used and how they are wired.
wrote...
#4
11 years ago
The first rule in electricity is SAFETY.  I would strongly recommend using a volt meter.

Black, red, blue are the proper colors for 240 volts.

208 volts usually has a "High Leg" and the higher voltage wire should be marked (taped) with orange.

480 volts 3 phase is brown, orange, yellow (think big BOY)
240 volts single phase should be marked (taped) black and red.

Once again, I would use a volt meter to make sure.
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