Live to neutral fault finding

[flyingsparks]

How would you suggest is the best way to find a live - neutral fault on a lighting circuit. Basically thre is about 8 fluorescents on the circuit, not RCD protected. Fuse is blowing fairly often, perhaps once every other day at present. I haven't tested anything yet, but suspect a l-n fault on a choke. ( the lights are quite old) obviously meggering is going to be a dead short anyway, so what would you do? Perhaps a resistance test on the chokes and see if one is lower than others? (Others disconnected of course.)

 

[ricicle]

In my experience a faulty choke will be down to earth. You will need to methodically test each light. If they are all of similar age then it could be time for new lights or ballasts anyway.
You could compare resistance with a known good ballast but the reading will be very low anyway as the reactance is inductively created.

 

[333rocky333]

providing there not h/f fittings, disconnect the circuit neutral and meggar circuit live to earth, as ricicle says there aint a neutral to a choke so they normally short to earth or if the windings short they usually blow the lamp electrode to bits

if there really old there ballasts and did have a neutral but usually the lamp wont work after they fail

could it be the start load of the fittings tripping the mcb

 

[flyingsparks]

Yes true, like I say I haven't checked readings yet, but if it is live to earth fault then easy enough to find. Don't think it's the start loading at 8x70w is 2.3A x 1.8 is 4.2A,. And it's a bs3036 5am fuse.

Will check readings next time I go to this site. Thanks anyway

 

[333rocky333]

My mistake you did say fuse

 

[RF Lighting]

Fit a 1 amp in line fuse in each fitting. It's cheap to do and only takes 5 mins per fitting. You'll soon find out if any of the fittings are faulty.

 

[Lectrician]

You can normally spot a failed or failing ballast by smell and sight.

A while ago, we had some lights in a corridoor blowing the fuse most days, took a little while to suss out.

The factory had been altered around, and a disused two way switch ended up in the kitchen area, behind a fridge.

Every time the fridge door was shut (or slammed really), the switch took a bashing. Eventually, there was very little left, and every time the door was slammed, the fuse would blow! The corridoor was not in sight of the kitchen area due to wall alterations, so no one but two and two together. How they didn't hear the pop was beyond me! Loud factory I guess.

 

[Spark123]

Yep, you can normally smell (and taste) a ballast when it is burning out!

 

[flyingsparks]

Thanks for all the useful good information. Will let you know when I go to site what I find, may get a picture for you too if its worth photographing!