Disturbing news from my HVAC guy

[Joseph Tribuzio]

An HVAC tech was at my mothers home doing a routine maintenance when his elbow brushed against the ac line. He received a shock and started to investigate. He found the outer casing of the AC was reading 105 VOLTS????

after removing everything giving a load he still could not find out why? but he replaces a single pole lennox a the shut off with a double pole. That seemed to mostly fix the problem. There is still some minor voltage , i think he said 15volts. We dont know why the breaker did not trip. Obviously one of the legs is making contact with something it shouldnt.

Has anyone encountered a similar situation? This guy and another veteran of HVAC were baffled.

[Doug Edwards, CMI]

Does this compressor have a heater?

[Bruce A. King]

Probably leakage from a conductor in the compressor to the case along with poor bonding of the case to ground. I would also verify proper connections in the panel for this circuits equipment ground.

[Joseph Tribuzio]

Originally Posted by dedwards

Does this compressor have a heater?

nope, just a outdoor ac unit.

[Joseph Tribuzio]

Originally Posted by bking

Probably leakage from a conductor in the compressor to the case along with poor bonding of the case to ground. I would also verify proper connections in the panel for this circuits equipment ground.

The panel is a Wadsworth, I haven't been there to look it over but im still puzzled why it would not trip?

[Andrew T. Shick]

Originally Posted by jtribuzio

The panel is a Wadsworth, I haven't been there to look it over but im still puzzled why it would not trip?

Plastic condensor pad?

[Bruce A. King]

Originally Posted by jtribuzio

The panel is a Wadsworth, I haven't been there to look it over but im still puzzled why it would not trip?

Voltage caused by leakage can have very little current capability available but it sounds like a bad breaker trip level could be present also..

Ever notice how a 14/3 or 12/3 cable will have 30-40 volts on the red wire when it is not connected to anything? This is "crosstalk" or simply leakage along the length of the cable from the black wire induced into the red wire. If you put even a very small load on that stray voltage it will disappear.

[Joseph Tribuzio]

Andrew, YEAH it is on a plastic pad.
Bruce, I'm going to take a closer look at that breaker and the grounding/bonding.
The crosstalk sounds like a factor too.

[Wayne B. Wilson]

Check the ground rod also

[Ronald l. Cook]

Check to see if the capaciter is not starting to short out.