60-120V on Drain Line

[Little Bill]

I was listening to a radio program that an electrician hosts and takes calls & emails and answers them on air. He was talking about a call he went to this week, the call was from the fire dept. They had gotten a call from a HO that her sink was on fire. When they get there they only see smoke coming out of it, so they cut the power and poured baking soda down the drain in case it is a chemical fire. She told them she washes her hair in the sink and it felt like her face was burning. They couldn't find the source of the smoke and decided to call the electrician. When he gets there he looks under the sink to make sure there are no exposed wires, there was no wiring under the sink. so he then cuts the power back on to check the sink. He said her drain (obviously metal) was broken and an attempt to repair it had been made by the HO by wrapping tape around it. He checked from ground to the drain where it connects to the sink and got a reading of 60+V. He then went under the area (basement or crawl IDK) and checked the pipe that the drain connects to and measured 120V there.hmy: He said he though he was only getting the 60V reading because of the broken pipe and it wasn't making a good connection. But when water was running it made a better connection and as he put it, "was boiling the water". He wasn't very descriptive of the problem or fix but did say it was a nicked wire probably touching the pipe. I'm guessing the water pipe wasn't bonded or at least lost the bond to the drain. He also didn't say whether the house had an EGC or not. What are you guys thoughts on this?

 

[Dennis Alwon]

I understand how the pipe can be hot but not sure I see how you can boil water in the pipe unless it is grounded somewhere and the CB is not tripping. Maybe someone will enlighten us.

 

[Little Bill]

I understand how the pipe can be hot but not sure I see how you can boil water in the pipe unless it is grounded somewhere and the CB is not tripping. Maybe someone will enlighten us.

I wish the guy would have explained a little further. It sounded like he ran some water to check it out before repairing it.

 

[augie47]

I'd like to see their power bill
I have seen electrical enclosures fill with water which boils and makes steam without tripping a breaker.
We don't tend to bond drain lines so I can see a scenario where a hot wire could come in contact with a ,metallic drain line which only had the earth as a return and you would read voltage to a true ground (or neutral) and over time the line would warm the water.

 

[captainwireman]

Hmm, possibly an energized mettalic pipe that goes to a non conductive style (clay, plastic?) drain pipe. When water(conductor) is run or the piping is wet, there is enough conductance to complete the circut but the resistance is high enough to not cause the fault current to trip the breaker. This would cause the heat. Interesting.