Current on panel cover

[John Gromkoski]

Did an inspection that had a sub panel at each of two levels. Without "ticking" the panel first (testing with my non contact tester) I started to remove the screws. I stopped my self and decided to "tick" the panel and discovered it had current running through it. I turned off the breaker for the panel at the main distribution panel and re-ticked the panel. No current. I proceeded to remove the cover. The only issue I could find inside the panel was that the panel was bonded to the grounding bar, and a double tapped breaker. I inspected the second sub panel at the floor below and discovered the identical situation - live current at the panel cover and panel bonded to the grounding bar. Why did my tester sense the current? Below is a photo of one of the sub panels, the bond to the ground bar. Also, check out the last picture. Why is that connection removed and bent back? I don't ever recall seeing that.

[Michael Larson]

Why is that connection removed and bent back?

Because grounds and neutrals are must separated on remote distribution panels and that strap would tie the isolated neutral bus to ground.

[John Gromkoski]

Originally Posted by mlarson

Because grounds and neutrals are must separated on remote distribution panels and that strap would tie the isolated neutral bus to ground.

Okay. I get that.

Any idea why there was current at the panel?

[Jeffrey R. Pope]

It's unlikely that the panel was actually energized. Your "tracer" is simply indicating that voltage is "nearby." A volt meter would confirm this.

[John Gromkoski]

Originally Posted by jpope

It's unlikely that the panel was actually energized. Your "tracer" is simply indicating that voltage is "nearby." A volt meter would confirm this.

Doesn't happen on any other panel I check. I check all panel covers and have never come across this.

[Robert Meier]

Originally Posted by jpope

It's unlikely that the panel was actually energized. Your "tracer" is simply indicating that voltage is "nearby." A volt meter would confirm this.

I would agree with Jeff, but it seems odd that it didn't happen elsewhere. Only a test with a different type of tester (non-induction) would confirm this.

[KEVIN WOOD]

Sometimes no matter how hard you try you can not find the source. The only way to find it is to remove all breakers and test for reverse wiring.
Not that I am saying you should.
Refer to "Certified Electrician"

[John Gromkoski]

Originally Posted by kwood

Sometimes no matter how hard you try you can not find the source. The only way to find it is to remove all breakers and test for reverse wiring.
Not that I am saying you should.
Refer to "Certified Electrician"

Reverse wiring? I'm not sure what you mean.

[Jeffrey R. Pope]

Originally Posted by jgromkoski

Doesn't happen on any other panel I check. I check all panel covers and have never come across this.

When you place your tracer on NM cable, it will indicate voltage, correct? The fact is, the sheathing is not energized, but the inductive-tracer warns that voltage is present or in close proximity.

You will find through experience that many panels and panel covers will give this same indication with an inductive tracer - sometimes with no real explanation. For safety sake, you should also carry a "contact" type tester (non-inductive) to confirm or verify the presence of actual voltage.

[Jeff Tatlock]

Originally Posted by jpope

It's unlikely that the panel was actually energized. Your "tracer" is simply indicating that voltage is "nearby." A volt meter would confirm this.

The 'ticker' checks for voltage (potential energy of an electric field); not current. As Jeff states, you can (and should) use a DMM to see if voltage is actually on the panel itself (measured between panel and known good ground). For example, you can tick an insulated wire with that carries 120V and have it beep, but the insulation is usually safe to touch, unless its broken down, that's where the DMM comes in...the ticker is just a first pass test.

[John Gromkoski]

Originally Posted by jtatlock

The 'ticker' checks for voltage (potential energy of an electric field); not current. As Jeff states, you can (and should) use a DMM to see if voltage is actually on the panel itself (measured between panel and known good ground). For example, you can tick an insulated wire with that carries 120V and have it beep, but the insulation is usually safe to touch, unless its broken down, that's where the DMM comes in...the ticker is just a first pass test.

I don't disagree with you guys that maybe a secondary voltage test should be made, but my understanding of this type of non-contact tester is that it will not detect voltage through a metallic cable or panel box unless there is voltage present. If I put the tester on an AC or MC cable it will not ring although there is live voltage present inside. This is what is getting me about these panels. I have tested lots of panels with this tester and never get a positive reading.

[Michael Larson]

Not all voltage sniffers are created equal.

Using a meter will tell you if there is any voltage available on the panel.

Using a wiggy will tell you if there is any significant current on the panel.

[ldapkus]

Originally Posted by jgromkoski

Reverse wiring? I'm not sure what you mean.

I don't think the CMI knows what he means either.

[Frank P. Newman]

I don't know about your tester but mine has a sensitivity adjustment that sometimes gets changed while in my tool bag. When at higher settings it will indicate voltage (not necessarily current) anywhere in the vacinity of an energized part.

[Paul W. Abernathy]

John,

It is very hard to speculate without being there and seeing clearly what is going on. Typically, the voltage detector ( actually a magnetic field detector ) will go off on some devices that induce a magnetic field onto the metal enclosure. The only real way to determine this is to test with a true voltage meter. It is not typical to get what you are getting on a good quality detector.....many times you will have one that detects static but wont actually sound off until it detected a substantial magnetic field.

The concern is I don't want you to dismiss it as nothing because to be honest with you we can't say it is nothing at this point without more testing. It is very possible that where they bent back the connector bar that leads to the grounded ( neutral ) buss is indeed bend back but is in contact with any of the grounding (bare) conductors which could potentially cause a similar issue.....

I have to admit my eyes are not what they used to be in looking in that panel but this would be a good case of having a spare ticker of a different brand just to be sure. But without getting into it and testing it myself I don't want to discount it and send that message to inspectors to ignore their testing equipment as that could be fatal.

My advice ( since we really don't know without a voltage meter ) if you have any additional issues in the panel or with the electrical to defer it for review by a licensed electrical contractor for two reasons. 1.) they will defer the responsibility for checking into it and testing it and 2.) you do not discount it only to find out it is a problem under close review by the electrician and then look bad in the eyes of the client.

Again, not all testers are equal as I believe someone said and we are not saying your tester is bad. What we are saying is anytime something can't be explained you have every right to call it out . I personally would not want to advise you to ignore it because lets say it is a problem with the equipment someone needs to resolve to why. If it happens in all the panels in this dwelling and you test it on another dwelling and it does not go off.....Defer the condition and let the electrical contractor resolve to conclude it is harmless.