Neutral to earth fault

[m4tty]

Hi,

Been to test a house today before changing the board over next few weeks. Found a few faults

Upstairs lighting 0.25 ohms continuity between neutral and Earth

Downstairs lighting. 0.18 M ohm l&n to earth. 0.21 Mohms live to earth and 0.15 Mohms neutral to earth.

Left it there as had really bad headache.

Question is any tips on fault finding other than breaking the circuit down and testing each run? Can't think straight at moment so any advice appreciated.

Thanks

 

[fletchflash]

is that with all conductors removed from the DB? tested with lamps in?

sounds like it could be same fault- maybe picking up through lamps and possible borrowed neutral? what readings do you get between the up and down circuits, neutral in particular?

If each circuit does have seperate faults then the best way is to break down, eliminating clear wiring as you go. That way you can be sure of clear sections, otherwise you'll pick up other paths and end up going round in circles!

best to split at a pendant in middle of circuit, disconnect at DB. when its clear aT DB reconnect clear wiring at pendants/JB's etc, put blocks on end of any dissconnected faulty wiring then power up and see what comes live.

 

[Andy™]

0.25 sounds more like a dead short somewhere. either at an accessory or a nail through a cable

other LOW IR is probably dampness somewhere or a damaged cable

either will give you problems

 

[Revved Up Sparky]

I would double check that there are no PIR sensors, dimmer switches, smoke/ heat alarms, discharge light fittings, neon indicators, TV amplifiers or other electronic devices still connected to those circuits.

 

[Evans Electric]

As Revved Up says , any fluorescents there or 2Ds ?

 

[sellers]

for your upstairs fault, get a long lead, connect it to the neutral of the faulty circuit then go round and measure the resistance at the earths, lowest restance should be where your fault is or as near as.

For the low IR its a matter of splitting up the circuit, I'd try switching all the switches first to eliminate switch wires