How To Track A Short Circuit In A Lighting Circuit

[iangorrie]

I am a DIY amateur electrician who has a problem with my kitchen lights. The fuse continually pops about 5 minutes after switching on the kitchen lights (a chandelier and 2 wall lights). The bulbs are low energy so total load is <100w and the problem occurs even when all of the bulbs are removed. I thought that the delay in blowing the fuse pointed towards a loose wire so I have taken all 3 lights off the wall/ceiling but all the connections appear sound. I did the same with the switch and eventually lifted the floorboards assuming the problem must be the junction box. Again all connections appear sound. I repaired the fuse and switched on while all of the connections were exposed and 5 minutes later when the fuse popped again there was no heat evident at any of the end points of the circuit. I am running out of ideas and any help to pinpoint the short would be much appreciated. If it helps, I have a multimeter that I only use as a voltmeter i.e. I need clear instructions if the answer involves using the resistance meter.

 

[AP Electrical]

Think you're probably best contacting your local spark to take a look, testing is something best left to professional with correct testing equip, chances are they will locate fault by the time you've got to grips with your multimeter, not being disrespectful just my honest opinion.

 

[iangorrie]

Thanks for your reply however I am going to persevere to fix the fault on my own. My next plan of attack will be to isolate the lights themselves as they are all antique (as is the house and the wiring!) and there is every possibility that the internal wiring (not easy to get a look at) could be faulty. Any other ideas on how to progress this without engaging an electrician would be welcome.

 

[kenny7askew]

think you need to carry out insulation tests but without the correct test equipment you ars going to struggle

 

[ezzzekiel]

split the circuit in the middle and test both halfs one will be clear the other show a fault, continue process till exact location found.

 

[iangorrie]

When you say test - what do you mean? I only have my multimeter and can't perform insulation tests with it.

 

[1shortcircuit]

When you say test - what do you mean? I only have my multimeter and can't perform insulation tests with it.

If your meter does not have an Insulation Resistance function then you will not be able to carry out that test. There is a way around it but to be honest it could be very long winded and dangerous if done by someone who may not be competent.

If the cable is as old as you say then it could mean the entire property requires a full or partial rewire. You need the correct equipment to do the necesary tests which MUST be carried out in a specific order as each test relies on the results of the previous test:thumbsup

 

[Specialist]

Short: He does'nt know how to use the Resistance function on the Meter mate, never mind Insulation testing.

 

[wallyanker]

When he says multimeter, I think he means £5 one for electronics.

iangorrie, to do an Insulation Resistance test, you need a proper test meter

 

[1shortcircuit]

Short: He does'nt know how to use the Resistance function on the Meter mate, never mind Insulation testing.

When he says multimeter, I think he means £5 one for electronics.

iangorrie, to do an Insulation Resistance test, you need a proper test meter

Sorry my Wife was nattering in my ear and I kinda lost concentration which is why I just edited my post to read

If your meter does not have an Insulation Resistance function then you will not be able to carry out that test. There is a way around it but to be honest it could be very long winded and dangerous if done by someone who may not be competent.

If the cable is as old as you say then it could mean the entire property requires a full or partial rewire. You need the correct equipment to do the necesary tests which MUST be carried out in a specific order as each test relies on the results of the previous test:thumbsup

After posting I saw your replies lol

:thumbsup

 

[AP Electrical]

iangorrie, have you done any decorating lately - christmas lights nailed to wall, hanging pictures and the like etc ?

 

[1shortcircuit]

What is the colour of the outer sheath of the cable used in your installation?

Please can I mention, I seriously believe that the problem you have should be left to an electrician or competent person with the appropriate test equipment. Fault finding CAN be long winded at the best of times.

If it's the popping of the fuse you're concerned about then just stick a small nail in place of the 5 amp fuse wire, that'll keep it going a while longer


*** Use information posted on a public forum by a complete stranger with no knowledge of their true ability entirely at your own risk - Electricity can cause fires, fatal injury and even death ***

 

[AP Electrical]

What is the colour of the outer sheath of the cable used in your installation?

Please can I mention, I seriously believe that the problem you have should be left to an electrician or competent person with the appropriate test equipment. Fault finding CAN be long winded at the best of times.

If it's the popping of the fuse you're concerned about then just stick a small nail in place of the 5 amp fuse wire, that'll keep it going a while longer


*** Use information posted on a public forum by a complete stranger with no knowledge of their true ability entirely at your own risk - Electricity can cause fires, fatal injury and even death ***

Is he putting that in place with a neon screwdriver (kitchen fitters installation tester ?)

 

[Specialist]

If it's the popping of the fuse you're concerned about then just stick a small nail in place of the 5 amp fuse wire, that'll keep it going a while longer
***

Now, Now 1SC we'll have no more of your Cowboy practices if you don't mind :shocked::tounge_smile:

 

[iangorrie]

With no easy way coming forward to isolate the problem, I took the simple route and rewired the 3 lights. Seems to have solved the problem and probably the safest option given the circumstances although I've now got a wall to patch up.
Thanks to those who tried to help.