Closet electricians – how can this happen? (1 Viewer)

[Dorwyn]

I've just noticed signs of arcing – black marks around the EARTH connection of the power lead plug that fits into the van at the van end. I've never had the van mains circuit blow, but I have in the past used some double dodgy power pylon connectors on continental sites. (I well remember one at the City site in Avignon). And until recently I always first checked the polarity before use. For the earth to be blackened, a current must a passed through it at some stage, and some RCD somewhere should have tripped. Shouldn't it? It's very unsettling.

 

[Odd job]

How black is it? A picture may help!

 

[Dorwyn]

No fear, it's raining out there! It's just a little ghosting, not excessive, and just around the white plastic end of the plug by the earth, not on the metal. I do not think it's serious, it's just unsettling. I think in future I will go back to checking the polarity first. On reflection, I did come across one on a site near Madrid, that showed an earth polarity issue. But I never used it.

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[hilldweller]

Can the earth arc ?

The earth is the long pin so that it makes first and breaks last, no path for an arc.

 

[maxi77]

possibly just corrosion, copper can go black when it oxidises

 

[The Nomad]

How can reverse polarity cause arcing?
That doesn't make sense...especially as you say the carbon blackening is around the Earth prong.

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[funflair]

Not on the metal?

Martin

 

[Dorwyn]

Can the earth arc ?

The earth is the long pin so that it makes first and breaks last, no path for an arc.

That's the sort of thing that confuses me, there should be no current on the earth. I could imagine something on the face of the plug if it was plugged in while wet.

Not on the metal?

Martin

No, the metal looks OK.

 

[tonyidle]

It's copper oxide staining or similar. There are no circumstances where the earth could carry current. Any arcing under such near impossible circumstances would occur at the tip of the pin as it was withdrawn. Have you checked for lightning bolt holes in the roof?

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[PeteH]

Check the Plugs on the ends of the Leads, IF the cable has been strained, say, by someone tripping over it, the cable can, especially if the Cable clamp is not fully tight, become partially detached, under those conditions, the resistance becomes high(er) and burning (arcing) could then take place. I had a similar thing happen with a Brand new lead some years back, welded it`self into a socket on a CC site took a (very) large screwdriver to remove AFTER the warden switched off the Outlet!.



The Result!. The cable had apparently never been properly attached when made up!

EDIT:- Recently I had a damaged cable which I shortened to 10M. when I made the "new" end up and tested it I discovered I had reverse polarity!. Checking the other end, I discovered that the Cable, Purchased some 20+years ago, had ORIGINALLY been made up wired Blue LIVE, Brown Neutral!. It worked OK obviously, but just shows how little you can rely on others doing the Job properly!.

 

[jdk62]

Check the Plugs on the ends of the Leads, IF the cable has been strained, say, by someone tripping over it, the cable can, especially if the Cable clamp is not fully tight, become partially detached, under those conditions, the resistance becomes high(er) and burning (arcing) could then take place. I had a similar thing happen with a Brand new lead some years back, welded it`self into a socket on a CC site took a (very) large screwdriver to remove AFTER the warden switched off the Outlet!.

View attachment 177863

The Result!. The cable had apparently never been properly attached when made up!

I have 3 mains leads and I take apart the plugs/sockets and check all connections twice a year. Bit needy but better safe than sorry. I was surprised when I would find a loose connection but then found out why it was happening- The Beauty Terrorist when disconnecting from the power pole was pulling the cable not gripping the plug!!!! Grrr.

She was suitably admonished, spanked and a good night was had by all.....

 

[fleurette]

Just wondering if at some time the plug has been wet and caused tracking across the plug from Live to Earth as you say that its on the plastic part?

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[Badknee]

I would check tightness of contacts first.

 

[jdk62]

I would check tightness of contacts first.

A maxim for life.....