Dead Short

[Sharpend]

Glad to hear it.

Well done.

 

[ProDave]

Thanks for letting us know, and glad it wasn't your work at fault.

 

[Doc Hudson]

hello.

thoughts please....

today we have 2nd fixed a lighting circuit. all ok until we connected the 4 way switches... and suddenly 230V goes down earth...

any way one of the 3 cores has a dead short on it about 0.45ohms. me thinks a screw.

property has been plastered and painting and they don't want any more mess.

now.... i have explained we need to replace the cable or find exactly where the fault is and join extend ect.

but if i disconnect the earth from both ends and put them in a block. this then means that cable will have no earth.

but at every point there is a contuinous path to earth from switches and fittings.

so there for what would you do.... ????

i know the best thing would be to replace the cable but you know how it is

umm not really down right dangerous..... if i leave a note at each switch and in the CU.

what else can i do if the client doesn't want their wall ripped to peieces

Hello all found the fault today.. Builder has build a stud wall and put a a bit of wood on the cable catching it. I have a pic.

It was a short of 0.08 at one end and 0.49 the other. There for I knew what end to start with. But hey all sorted now. I wasn't ever going to leave it.

Thank you for the feedback, I will however just point out that from the above three posts you made, it does give the impression of either a bit of fibbing or blatant wind-up in part of your content. e.g. "if i leave a note at each switch and in the CU. what else can i do if the client doesn't want their wall ripped to peieces" -VS- "But hey all sorted now. I wasn't ever going to leave it." I would remind all members that you will get the best out of the forum if you are open and honest when posting questions and giving detail.

Doc H.

 

[SPECIAL LOCATION]

Hello all found the fault today.. Builder has build a stud wall and put a a bit of wood on the cable catching it. I have a pic.

It was a short of 0.08 at one end and 0.49 the other. There for I knew what end to start with. But hey all sorted now. I wasn't ever going to leave it.

Good of you to tell us what you found....

Just for the benefit of less competent bod's (Students) who may be reading this thread......

Assuming leads have been correctly zero'ed.....

rough distances can be calculated using the R1+R2 resistance tables on page 182 of the on site guide.......

0.08ohms would be 2.2m if 1.0mm cable or 2.6m if 1.5mm cable...

0.49ohms would be 13.5m if 1.0mm cable or 16.2m if 1.5mm cable...

So allowing for tolerances due to the durability of the connection between test meter and conductors...

And the unknown resistance of the actual faulty part that is bridging the cable....

You can get a rough idea where the damage is...

 

[Apache]

Glad this got sorted.

I was expecting a thread about vertically challenged sparks.............

 

[M107]

Well done on getting it sorted

 

[mikep]

If you have installed it right then it's not your fault so find it and make it safe.

I had a roofer using a nail gun banging in 96mm nails to secure a 20mm batten to 18mm ply, 58mm protruding into my cable, made him pay for the tracing and repair.