Why is Half of the Power Out to my House?

When customers call to report an outage, one of the first things we ask is if they’ve checked their breakers. Many would-be outages are merely tripped breakers. If a customer hasn’t checked their breakers (or generator, or security system) and calls afterhours, a $250 charge may be assessed if the cause of the outage is customer equipment.

Sometimes however, power will be out to one part of the house and not the other without any breakers having tripped at all. Even stranger will be flickering lights, appliances or equipment that don’t seem to operate properly, or don’t operate at all.

While in a very old home this sort of problem could be caused by ancient wiring, rodent colonies, and/or ghosts, in homes with relatively up-to-code, modern wiring, the problem might be outside.

At most homes and businesses in Jefferson County, three wires run from PUD transformers to the meter at the home. Two of the wires are “hot.” They supply the electricity from the transformer to the meter. Each carry 120V, and when combined by a double pole breaker, they can supply 240V to appliances like driers or electric ovens. The third wire is the “neutral” carrying power back from the house to the transformer.

Due to repeated expansion from heating when in use, and cooling and shrinking when not, over time the hot wires can sometimes work themselves loose of the connection that holds them in place. Or, if they get too hot, due to overloading or power surges, the metal wire itself might burn, melt, or otherwise degrade. At the transformer, connections can also be corroded by the saltwater that naturally makes up some of our coastal air.

So, if power suddenly goes out to part of the home, but no breakers trip, it could be that one of the two hot wires has become loose (causing flickering) or disconnected (no power). This can happen at the transformer, in the meter base, or at the connection to the main breaker in the panel.

Similarly, the jaws or sockets that hold an electrical meter in place and transmit power through it, can wear and weaken over time. As they heat and cool, the grip of the jaw loosens. If it loosens enough, it allows for minute arcing between the jaw and the meter, leading to melting or burning of the metal socket. Eventually this can lead to loss, or partial loss, of power.

If you’re experiencing loss of power to part of the house, and your breakers remain untripped, give the PUD a call during working hours. We can schedule a crew member to inspect our equipment and repair any issues they find. It’s a good idea to alert a licensed electrician at the same time, especially if we have to turn off power for repairs to be done inside.



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