Melted Wirenuts

Specific Inspection Topics Electrical Inspections
#1

I inspected a house over 9 months ago and now some wirenuts melted on the water heater and burnt up the board. A licensed electrician has told my client that a power surge caused the wirenuts to melt. I think it is do to loose wirenuts but the breaker should have tripped or the water heater is shorted out but the breaker did not trip. It was a 40 amp breaker on #8 wiring.
What do you guys think?
And an article about what might went wrong, would be nice.

The electrician never even looked at it, but talked to my client several times on the phone saying I was wrong.

#2

On a message board, I’m thinking I wouldn’t be able to hazard a guess any better that what the electrician did over the phone.

Both scenarios sound plausible.

Did you see it?

#3

James, circuit breaker would unlikely trip in this situation if it was due to a loose connection. The loose connection generates heat at the bad connection, not at the breaker so it would not trip. There is explanation number one against power surge.

There will be a rise in amperage draw through the breaker due to the energy loss (making heat), but this is hardly measurable for the breaker.

If in fact you did have a power surge, the fact that only the wire nuts got hot means that there was still a loose connection there!

Voltage surges do not last long enough to melt things, rather they explode things!

So without seeing it, I would tend to support your stance on this issue.

The fact that the electrician did not even evaluate (look at) the situation says enough about the accuracy of his reporting.

#4

What David said !:mrgreen: I’m not sure how to define “power surge” anyway even though it is commonly used to try and explain away many things that may have been poor workmanship.

#5

Yes, had a thin arc mark through the wirenut all the way around.

#6

A power surge would be when the voltage exceeds the prescribed level. Normally these are short duration events.

Power sags would be when the voltage is lower than prescribed. These can occur when large loads like compressors or motors start up.

#7

I understand, but I also know that many people use the catch-all “power surge” to describe many different type of electrical events - often used to try and pass off a problem as an “act of God”. Other than as a result of a nearby lightning strike, true power surges are really pretty rare in the residential setting.