Why does my 120 volt outlet only measure 74 volts?

Answer 1

Answer for USA, Canada and countries running a 60 Hertz supply service.

The voltages 115 to 120 volts are a nominal figure in the same voltage range. It is brought about by the power company, as they have a responsibility to keep voltages within a certain 10% range. The load will only notice a difference of 1% on the load current. e.g. Wattage load of 2400. Amps = watts/volts. 2400/120V = 20 amps. 2400/115V = 20.8 amps. On a constant resistance as the voltage goes lower, the current goes higher and vice versa as the voltage goes higher, the current goes lower. Usually in the daytime when use is in heavy demand, the voltages will be a the lower end of the scale where as in the night time, when demand is lower, the voltage level will be at the top end of the scale

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Transmission losses between the transformer and the point where you are measuring.

Answer 2

This would be abnormal. My first guess would be measurement error - how are you measuring this? Is your volt meter accurate (for sure)? Is it meant to be used at 120 volts?

If you're sure it is actually 56 volts, then has this always been this way? Is it a new outlet? If it is, is something getting hot (undersized the conductor, really really long feed?), is the sparking in the breaker cabinet? Is the breaker getting hot?

I assume this is a single phase (normal house wiring), not some sort of 3 phase ungrounded delta type connection? If it is ungrounded, this could be normal if you are measuring to ground, since it is essentially "floating" under normal conditions (ie a phase to ground measurement is meaningless on an ungrounded system).

Answer 3

In most cases when this happens it is the testing meter that is At Fault. Make sure that you zero the meter out if it is an analogy type meter. Check the batteries in the unit. Check the voltage on other circuits or a neighbours outlet and see if the reading is the same. If other circuits or the neighbours read 120 volts, the meter is correct and you have a problem in your house. Two thing should be done, first call an electrician to check the problem out. If the electrician confirms the problem get him to call the utility company and he can explain the situation to them. If you call the utility company and complain you will get questions from them that you will not be able to answer.

Answer 4

It's faulty and needs repairing.