Power Strip Failure

[fifty60]

I have an old power strip that, when plugged into a 120V 15A outlet, is showing 39V between the neutral and ground.

What could have failed inside of this to cause that? The neutral must have somehow become separated from ground right? Is this common on older power strips?

 

[ron]

The voltage is showing impedance back to the source for the neutral.

What is the N-G voltage at the receptacle direct?

 

[iwire]

What is the N-G voltage at the receptacle direct?

I agree that would be my first check.

 

[ron]

This is an interesting article about the issue

http://ecmweb.com/power-quality/clearing-neutral-ground-voltage-confusion

 

[Jraef]

In my experience with this on "surge protected" power strips, as many of them are now, is that they had an MOV between N and Ground, and it has vaporized inside of the power strip. Should be obvious when you open it up. If not totally vaporized, the other telltale is that the MOVs are usually blue, yellow or red, but turn brown or black after failing (doing their job).

 

[fifty60]

The MOV is going to pass current from positive or negative voltage peaks over a certain threshold. I understand that it is connected between the neutral to ground, so that if any transient voltage spikes happen between line and neutral then the neutral will be shorted to ground at the varistor. So if this opens up, how would that cause what I am seeing?

Is the failure mode to short the neutral and ground together? How does that cause voltage to show up between neutral and ground? Why doesn't it just short and trip the breaker? Does it completely change the path that the ground takes back to the source by parallelling it with the neutral? That doesn't make sense...Its obviously creating impedance somehow between ground and the source ground...

 

[fifty60]

So it is actually not a surge protector, but a standard power strip. The receptacle it was plugged into checks out fine. Any other suggestions on what to look for?

 

[cowboyjwc]

For the amount of time you've spent trying to figure out what's wrong with it, you could have just replaced it and moved on.

 

[mike_kilroy]

Inductors in Series with hot and nuetral input and output.

Movs from hot to grd and hot to nuetral.

Hot to nuetral Mov semi shorted leaking 36v.

Clip out all movs and throw away. Case closed.

 

[gadfly56]

For the amount of time you've spent trying to figure out what's wrong with it, you could have just replaced it and moved on.

At some point, it's not about fixing, it's about the "why" it needs to be fixed. I get drawn into the same type of thing, unless "Elementary" or "Mythbusters" is on.