I am making repairs to my house wiring. The house is 46 years and is in San Diego. Many of the junction boxes have two blue wires and a white running through metal conduit. I am use to black, white, bare, red and geen colors so am confused what the blue ones are for. With only a white and two blues I am not sure how to distinguish their purpose. Thanks for any insight and help.

You will need to test the blue and white wires to determine their purpose. Seems that whoever pulled wire back then did not follow the traditional color code.

You need to use a voltage tester to test across each blue to the white, also test across a blue, once you find which one is hot, to the conduit, which is probably being used as an equipment ground, which was and still is allowed.

Assuming the white is neutral, you should see 120 volts across a blue and the white. You should see zero or almost zero across the white and the conduit.

Thanks tkrussell. It appears the Blue wires are; one a hot and the other for a switch outlet. I was confused because the second blue began at the 1st junction box and continued to two other rooms and a hall each with a switched outlet. Since I am rewiring and each room will have a separate circuit it won't be a problem. I was trying to draw out the circuit. I guess blue was the color of the day.

Be careful breaker size, 15 amp-#14ga wire, 20 amp-#12ga wire, copper.