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Bulb Trips The Circuit


gravino

Question

This one has us confused....

 

Light circuit includes a switch to turn on/off a porch light.  All testing of the circuit (by our electrician) indicates it's a good circuit... but put a bulb in and the circuit trips.  Of course we've tried different bulbs and fittings but a little stumped...   I did ask if there is a possibility of using a bulb that draws less power i.e. LED, would that work?  Any tips would be of course, gratefully received.

 

Graham 

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I am absolutely wowed by the responses here, I just logged on to see if there was a reply and there are loads - BIG thanks to you all.....

 

We've replaced an old consumer unit with a new double one and when on the old unit this fault was not apparent and using the light didn't trip anything.  Using the light now trips the main RCD.   Yes, testing the circuit proves ok, adding a fitting and socket causes the trip.   I'll get the electrician to read these responses (including the ones that recommend someone else...!!), I also wondered if it was a 'load' thing and if a low 'load drawing' bulb would maybe help..  Please don't have a pop at me, I'm just the client with daft ideas to 'help' who's hoping for a fix... :)

 

I'll get more info as this thing progresses......

 

Btw...

 

Trailer Boy - Electrician. - Electrician has mentioned this could be the case, just not found it yet

Badger... Meters are being used (though I'm not the one that's using it - probably for the best!) - I will keep your offer in mind

IzzyS - I looked for a Forum to see if I could help i.e. getting other input can sometimes help the 'penny drop' and help find another route to a solution, I assure you - it's not me fiddling with the cabled here ;) 

ProDave - Expecations can vary I expect.. I'd like a working light but am realistic that it can take time to find a fault, that's why I am happy to work with the Electrician to help solve the issue in any way I can

Murdoch - Us = Me (Graham) and the Electrician (Frank)

Manator - So using Compost to help bed the bulb into the socket is not recommended then? 

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Let's be clear here....

A circuit that tests ok will NOT trip a RCD or MCB

So,,, if it passes the insulation resistance tests then there's still a possibility of a borrowed neutral

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So your "electrician" changed your consumer unit for a "new double one" which I assume means it has two RCD's?

 

And ever since the change, using this light has caused the "main" rcd to trip (quite which one you mean by the main rcd when there are two I am not sure)

 

This sounds like a classic case of borrowed neutral, a fault that would not have bothered the old fuse box but should have been found and corrected when the "electrician" changed the consumer unit.

 

Give him a chance to prove himself competent and call him back (show him this thread?) if not you need someone who is competent.

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Yep

As almost everyone else has said.....borrowed neutral

OR since you have had a new board fitted....one side of cct is frommRCD other side isnt ( still a borrowed shared neutral)

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or when he said 'main RCD' he means there is only 1 protecting everything...

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Wonder how long Frank has been a spark?

What does the certificate say? Has he notified it yet?

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depends if the porch is upstairs or not?

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Might not be a porch.....might be a merc

Just saying

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Cant believe no-ones mentioned borrowed neutral yet, or implied that the original spark may not be worth his salt :innocent

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Cant believe no-ones mentioned borrowed neutral yet, or implied that the original spark may not be worth his salt :innocent

Yeah, I thought that a bit strange as well

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Might not be a porch.....might be a merc

Just saying

 

or it might he a horse. then agian, that could be Rodney?

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Borrowed neutral tripping RCD me thinks?

 

:innocent

 

If so...

 

as has been said..

 

get a "proper" electrician to sort it out.

 

 

Unlikely unless there have been some recent modifications we have not been told about.

 

More likely an actual fault that the incompetent first electrician failed to find.

 

I still stand by post#6

 

Whenever anyone comes to a forum asking for advice there is very often been some alteration or changes that are not always fully disclosed in the opening post..

 

Bog standard IR testing will not show up a borrowed neutral...

As the "fault" path is not from either live or neutral to earth...

 

And if he's just done a global IR test across Live and Neutral combined to earth then no way he's going to spot it...

 

Sounds like a 5ww short course Board change to me?

 

:popcorn

 

 

p.s.

Borrowed neutral are not always between lighting circuits...

 

I've seen plenty of lights getting their neutral from a socket circuit..

(especially in bodger conservatory extension....

Live from the light switch.. neutral back to the nearest socket!!!!!   :shakehead )

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I was starting to consider that someone had picked up a neutral from a socket below the switch ;)

Or maybe.... A double switch using the earth as a SW L and picking up a neutral from the socket circuit in the bedrooms..... :o

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I still stand by post#6

 

Whenever anyone comes to a forum asking for advice there is very often been some alteration or changes that are not always fully disclosed in the opening post..

 

 

Yes in this case the alteration was the fitting of the new consumer unit.  How anyone can think that is not relevant and therefore omit to mention it in the OP I just don't know.

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porch is bottom of the stairs then.

I got up one morning and there was a Boeing 747 parked up,outside our bedroom door......we live a mile from the runway.

Wife's fault.....

She had left the Landing Light on all night

Sorry Rev

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I am absolutely wowed by the responses here, I just logged on to see if there was a reply and there are loads - BIG thanks to you all.....

 

We've replaced an old consumer unit with a new double one and when on the old unit this fault was not apparent and using the light didn't trip anything.  Using the light now trips the main RCD.   Yes, testing the circuit proves ok, adding a fitting and socket causes the trip.   I'll get the electrician to read these responses (including the ones that recommend someone else...!!), I also wondered if it was a 'load' thing and if a low 'load drawing' bulb would maybe help..  Please don't have a pop at me, I'm just the client with daft ideas to 'help' who's hoping for a fix... :)

 

I'll get more info as this thing progresses......

 

Btw...

 

Trailer Boy - Electrician. - Electrician has mentioned this could be the case, just not found it yet

Badger... Meters are being used (though I'm not the one that's using it - probably for the best!) - I will keep your offer in mind

IzzyS - I looked for a Forum to see if I could help i.e. getting other input can sometimes help the 'penny drop' and help find another route to a solution, I assure you - it's not me fiddling with the cabled here ;) 

ProDave - Expecations can vary I expect.. I'd like a working light but am realistic that it can take time to find a fault, that's why I am happy to work with the Electrician to help solve the issue in any way I can

Murdoch - Us = Me (Graham) and the Electrician (Frank)

Manator - So using Compost to help bed the bulb into the socket is not recommended then? 

 

 

This sentence suggests to me that the spark is non existent. What decent spark would allow a customer to help them change a CU?

 

Madness

 

 

We are not being told the whole story me thinks!

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If someone says "We've put in a new kitchen"  doesn't mean that they helped to actually fit the kitchen.

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If someone says "We've put in a new kitchen"  doesn't mean that they helped to actually fit the kitchen.

It depends if you take the English language at face value or trust it's adaptation to every day speech.

In true English the phrase "We have put in a new kitchen" does imply that they have assisted in the construction. However these days it is not uncommon for people to say things like "we have had a new extension built" or "we have had a new bathroom fitted" and there are no assumptions on the listener that they have done so themselves.

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What trips? Is it a MCB or RCD?

If it still trips after your electrician had tested it then I don't think much of their testing methods.

However I have had a lamp that had a short cct between the fillament and the BC cap

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try with another lamp. if it still trips, call another electrician who actually know hows to test, the one you have doesnt

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Yes what's needed here is a different electrician.

 

If it's tripping then it can't be "a good circuit" so you need a better electrician who understands fault finding.

 

Make sure he tests it with a lamp in the fitting and the switch turned on.

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Has there been any recent "unadmitted fiddling" ithnthemcct?

Is,it a new cct?

If either of the above are true then it could be a crossed neutral onnthe RCD side of the board, wrong connections in fiiting using say that nice soil coloured wire as earth and the bright funky green yellow one as a live

Loads of possibilities really

First step....try another lamp

Secondvstep....try another "electrician"

Just saying

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Borrowed neutral tripping RCD me thinks?

 

:innocent

 

If so...

 

as has been said..

 

get a "proper" electrician to sort it out.

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