Recently I was checking out an electrical failure at a friend's house and put a meter on the output of each of the breakers to see if failure had occurred in one, even tho they were not tripped. I was amazed to see that one of the two sides of the power read over 123 volts to neutral and the other read just at 120 volts.- American "110/220" house power. Appliances must work within a 110-125 range measured to ground but I expected the legs to be almost identical. I admit I haven't measured a bunch of them, so I ask here. [I contacted TXU Electric, but under deregulated power in Texas, they won't answer it referring it over to Oncor, the spun off power delivery company.]
2007-12-13 03:17:47 · 4 answers · asked by Mike1942f 7 in Science & Mathematics ➔ Engineering
All good answers, that is roughly what I thought, but curious, thanks.
2007-12-13 06:52:07 · update #1
The difference you measure is minor and I cannot think offhand any application that would be affected anyway. Most appliances use either one leg and neutral or both legs (240v) so a difference would be unnoticed.
There are regulatory tolerances the supply company should adhere to. Of course they wont tell you it because they don't want to be held to them. There are also a bunch of opt outs anyway.
2007-12-13 04:11:10 · answer #1 · answered by Poor one 6 · 2⤊ 0⤋
A load that is balanced between the two legs will have no current in the neutral and there will not be a voltage difference. A high impedance fault in one leg would also cause a differential voltage. Anything causing a significant voltage drop in the neutral could cause the voltage difference.
Check for current in the neutral and check to see if there is a bad connection on the neutral wires as well.
2007-12-13 12:52:57 · answer #2 · answered by tigerbaby99 3 · 1⤊ 1⤋
I do not see a problem with this - both phases are in spec.
Its probably due to heavier load on one phase than the other, but 3 volts is less than a 3% difference. Most appliances see only one phase or the other. For those that operate at 240 volts, they would likely not see the difference in voltage between the phases - they usually run phase to phase.
2007-12-13 11:24:27 · answer #3 · answered by Chuck 6 · 2⤊ 0⤋
nothing wrong with that..5% differential is standard i believe...also check the 220v coming into the house at the breaker..sometimes if one side of the 110 to ground might be drawing more amps than the other side which will vary the voltage..if an appliance or lamp is starting to go bad it could affect the voltage source...but i dont see any problems with your power...also check the breaker connections to make sure they are tight...
2007-12-13 11:30:00 · answer #4 · answered by ? 6 · 2⤊ 0⤋