I recently had a 12v socket external fitted. I'd been noticing that it "hummed" when I used it to charge phone etc. It took a few days and I realised that the external light would come on whenever I had something plugged into said socket.

my question is why? I've contacted the company that did the work and I suggested that there was a wiring problem.  The response was standard, nothing we've done, But I'm begging to differ on that. 

Anyway, I've rung ahead to a town I hope to hit next week, the rv repair place there have been great and said they can fix the problem.

But I would really like a heads up of what has happened here re the way it's been wired. Also, does it have to be done by an electrician or is it something rv repairers  just do? 

Thanks,

MJ

MaryJane wrote:

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I recently had a 12v socket external fitted. I'd been noticing that it "hummed" when I used it to charge phone etc. It took a few days and I realised that the external light would come on whenever I had something plugged into said socket.

my question is why? I've contacted the company that did the work and I suggested that there was a wiring problem.  The response was standard, nothing we've done, But I'm begging to differ on that. 

Anyway, I've rung ahead to a town I hope to hit next week, the rv repair place there have been great and said they can fix the problem.

But I would really like a heads up of what has happened here re the way it's been wired. Also, does it have to be done by an electrician or is it something rv repairers  just do? 

Thanks,

MJ

 

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HI Mary Jane 

Definately sounds like a wiring stuff up 

That hum could be a bit of a worry 

I woudf afford using the socket if possible until it is fixed

No you should not need a licensed electrician 

ANY reasonably competent AUTO electrician should be able to find & fix the problem.

PeterQ

Phil C wrote:

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MJ

Have you tried a different appliance in the socket? The fault may be the appliance or its plug and not the new wiring.

Suggest you try another appliance to see what happens.

Safe travels

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 Thanks both for replies. I tried 3 different appliances Phil, one made

 exterior light go really bright, the other produced flashing disco light, and the third the light was on dim.

so I just won't use it til I've had it looked at.

cheers

MaryJane wrote:

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Phil C wrote:

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MJ

Have you tried a different appliance in the socket? The fault may be the appliance or its plug and not the new wiring.

Suggest you try another appliance to see what happens.

Safe travels

---

 Thanks both for replies. I tried 3 different appliances Phil, one made

 exterior light go really bright, the other produced flashing disco light, and the third the light was on dim.

so I just won't use it til I've had it looked at.

cheers

---

HI Mary jane

That indicates the light & the plugsocket are connected in series OR as Exa has said  an neg return is faulyt or missing

Sounds like very poor workmanship in either case!!

Suggest you get the ones who do repair it to give you the details of what they find

Then throw that into the face of the first mob who appear to not be interested in their stuff up !

PeterQ

oldtrack123 wrote:

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MaryJane wrote:

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Phil C wrote:

---

MJ

Have you tried a different appliance in the socket? The fault may be the appliance or its plug and not the new wiring.

Suggest you try another appliance to see what happens.

Safe travels

---

 Thanks both for replies. I tried 3 different appliances Phil, one made

 exterior light go really bright, the other produced flashing disco light, and the third the light was on dim.

so I just won't use it til I've had it looked at.

cheers

---

 

HI Mary jane

That indicates the light & the plugsocket are connected in series OR as Exa has said  an neg return is faulyt or missing

Sounds like very poor workmanship in either case!!

Suggest you get the ones who do repair it to give you the details of what they find

Then throw that into the face of the first mob who appear to not be interested in their stuff up !

PeterQ

---

 I have to agree with PeterQ, the workmanship sounds very ordinary.

Could this be the actual wiring mistake? Perhaps the electrician picked up the negative return on the wrong side of the external lamp (the lamp's low resistance may have confused him).

        light
        switch
                   exterior
 B+ o--|--/ ---|---- light -----|
       |       |               _|_
       |       |                =
       |--o o--| 

        external
         socket

It would be interesting to see how the external appliances behave when the switch is closed, or when the lamp is removed.

dorian wrote:

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Could this be the actual wiring mistake? Perhaps the electrician picked up the negative return on the wrong side of the external lamp (the lamp's low resistance may have confused him).

        light
        switch
                   exterior
 B+ o--|--/ ---|---- light -----|
       |       |               _|_
       |       |                =
       |--o o--| 

        external
         socket

It would be interesting to see how the external appliances behave when the switch is closed, or when the lamp is removed.

-- Edited by dorian on Friday 31st of October 2014 06:23:56 AM

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 Hi Dorian

Would they use a chassis return or two wires? Its a very odd fault by the sound of it. Would love to get my multimeter in there 

Take care

Phil C wrote:

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Would they use a chassis return or two wires? Its a very odd fault by the sound of it. Would love to get my multimeter in there 

Take care

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 HI Phil

The usual practice with vans is to use a two wire system for the VAN wiring , BUT who knows what this mob might have done

Dorian's is also a definate  possabilty

The plug will work if the switch is OFF & the light wll glow ,but  if the switch is "on" the light will work full bright but the Plug socket will beuseless

But one thing is certain, the current is flowing through the plug & light in series.

The idiot obviously did not bother to check his work !! 

PeterQ

I'm not familiar with van wiring, but the only other possibility that comes to mind is this one:

        light
        switch
                   exterior
 |-----|--/ ---|---- light -----o B+
_|_    |       |
 =     |       |
       |--o o--| 

        external
         socket

ISTM that it would be easier to tap into existing wiring than to install separate cable runs. Perhaps that was the installer's reasoning.

I'm thinking that another test would be to measure the voltage between the socket terminals while turning the light switch on and off.

thanks again for all the replies. I totally dont/can't get electrics but you have given me good insight... And I'll be sending the bill to the company that did the work