[Jribbens]

In our lab there was an old air compressor that died years ago. We had an electrician hard wire it in to a what appears to be furnace electrical switch. The switch was activated and deactivated from a light switch on the wall. The trouble is now we wanted to wire it into a outlet box to plug in the new compressor, but the wires all seem to be live one white witch bypasses the furnace switch thing(we assumed it was ground. And two red. The mutimeter reads a charge for all lines including white. I wired it as if white was ground and was able to plug in a light successfully but the compressor made the switch box hum and the compressor sounded muffled. Thought I mixed up the positive line and negative and switched it but still failed. Please help

[drtom4444]

You need to trace the wires back to the breaker box and disconnect two of the wires from the breaker and put in a new breaker with one hot instead of three. It sounds like you have a three-phase line and you want a single-phase receptacle. Wire the white to neutral where you see all of the other white wires in the box attached. Mark one of the red wires with green tape, if possible on both ends and attach it in the box to ground. The other red wire goes to the new breaker. On the receptacle you will attach the red hot wire to the brass screw the white wire to the silver screw and the red ground wire to the green screw. When attaching these wires in the breaker box use an insulated screwdriver where the shaft is insulated with a plastic sleeve and good insulated needle-nose pliers. Use your ohm meter to check which red wire is which. With the power off to the lines after wiring both the white and the red into the box you will read zero ohms between the red and white at the receptacle and those go to ground and neutral. The other red wire is hot. It would be best to leave the red you are using for a hot wire off until you wire the receptacle and wait to hook it up last to the new breaker. Good luck. DrTom4444