You just never know!!!!!

[ADS]

Went fault finding today on a RFC.

Apparently, the MCB has been tripping intermittently.

It's a split load (single RCCB) - lights and a socket radial (one double) on the RCD side..............RFC, Shower, boiler on the other side.

That should have made me suspicious straight away.

Anyway, isolated whole board and completely removed the two legs of the ring from the CU.

Simple things first - end to end continuity...........there was continuity, but measurements were in the Kohms range - not good.

IR tested.....L-CPC, L-N, N-CPC..... all bad - 0.02 Mohms or there abouts.......N-CPC being the worst.

To cut a long story short, I removed socket fronts, continuity to find which socket fed which etc. and IR tested each section of cable.

Discovered there is at least one JB hidden somewhere and that there was a spur feeding two double sockets.

Also discovered there was a bad section of cable between two sockets.

Thought best solution would be to remove bad cable from circuit and form two 20A radials.

It was getting a bit dull now, so I re-energised the board so I could use the lights.

I formed the two radials and replaced the socket covers and headed back to the CU for the tests.

IR test radial one -

>299 Mohms N-CPC, L-CPC, L-N

IR test radial two -

N-CPC >299

L-CPC.............meter starts beeping and registering 230V between Line and CPC??????

I couldn't believe it, so I double checked with my Martindale.....it was true.

I'd just replated all the sockets with 230V on the 'Line' conductor.....felt a bit ill.

Knowing the voltage had to come from somewhere, I started opening the MCBs..........turns out to be the shower??

I asked the customer and he insists that the 6mm feeding the shower is one continuous run from board to shower(via isolator), but I wonder!!

I wanted to post this as a little reminder that you just never know when or how something might be 'live'.

I also wondered if anyone had any ideas..........I'm back there tomorrow to carry on.

I guess we don't have to wonder why the original spark put the sockets on the non-RCD side of the board. X(

 

[hifly]

I would do a bit of dead circuit tracing with a tonner i use (got from a nice bt engineer)

 

[Robin Spark]

If i understand this correct in that when you close the shower mcb then you get 230v on socket radial?

Erm wonder if there is a shower pump feed taken from shower switch then at a later date that feed has been taken back to RFC.

I'd probably do visual on shower and switch, continuity and IR check between line conductors of shower and RFC to start, maybe quick look up the loft for dodgy junction boxes near the bathroom.

Apart from that not sure what else to suggest.

 

[Nicky Tesla]

Has someone been lazy and tapped into the ring to supply the shower at the shower end and to a jb nearer to the CU fuse board end?

Crazy i know just a guess.

 

[ADS]

Ha Ha - Canoeboy, you're still on my ignore list ..........someone's going to have to quote you.

 

[Robin Spark]

Has someone been lazy and tapped into the ring to supply the shower at the shower end and to a jb nearer to the CU fuse board end? Crazy i know just a guess.

You mean that visually there is 6mm cable at either end on show but really its 6mm-2.5mm-6mm. Bit naughty, but there was an electrician in wolverhampton that did things like that until he got put behind bars!

 

[ADS]

One thing I forgot to mention is that I also tested continuity between the two neutrals (shower and sockets) before I left - there was none (open circuit)..........so it's just the 'Lines'????

What I'm wondering is, if this hasn't been done deliberately, what's the chances of both cables being damaged, only the line conductors, and in exactly the same place as to cause a short.

If not accidental, why would anyone connect the Line conductor of a 6mm shower circuit to a RFC?

 

[Robin Spark]

One thing I forgot to mention is that I also tested continuity between the two neutrals (shower and sockets) before I left - there was none (open circuit)..........so it's just the 'Lines'????What I'm wondering is, if this hasn't been done deliberately, what's the chances of both cables being damaged, only the line conductors, and in exactly the same place as to cause a short.

If not accidental, why would anyone connect the Line conductor of a 6mm shower circuit to a RFC?

1. Rip off cowboy, pretending to install 6mm cable but instead of lifting all of the boards and doing the job correctly he has only used a few metres of 6mm

 

[batty]

I would suggest a rewire.

 

[ProDave]

Should have used a NEON screwdriver to fit those socket fronts, then you would have noticed they were live :coat

Now I'm going to regret asking this. What's an RFC?

 

[Badger]

Should have used a NEON screwdriver to fit those socket fronts, then you would have noticed they were live :coat
Now I'm going to regret asking this. What's an RFC?

ill help you out me laddy :slap :slap

ring final circuit

:worship:worship:worship

 

[Technician]

Could have been a Rugby Football Club...but that is one scrum to avoid in this case.

 

[ProDave]

ill help you out me laddy :slap :slapring final circuit

:worship:worship:worship

Yes I knew I would regret asking. I feel like my avatar now

 

[a1]

Yes I knew I would regret asking. I feel like my avatar now

:slap

 

[Evans Electric]

I thought he was working in a Rugby Football Club also.

How can one tell if the reference is to a Ring Final Circuit or a Radial Final Circuit . These things seem to creep up on me , last year I was wondering what a MET was and now I have to remember that the Neutral is now Live and they are both called Lines while the Earth wire changes name about 3 times a year .

The best one they ever came up with was to alter the voltage ranges from Low, Medium and High .

Now up to 1000V is Low , :C wonder how much that part had to drink when he thought that one up .??

 

[ADS]

'Twas a ring final.....not a rugby club ha ha.

Good point Evans - about it standing for either ring or radial.

Problem solved, anyway.

Found that 2.5mm and 6mm did run together up a wall.

Someone fitted a built in wall cabinet and drilled & screwed right between the two of them - nicked the 'line' conductor on the 6mm and grazed across all the conductors on the 2.5 - metal rawlbolt meant that it was impossible to isloate one without isolating the other.....great!!

 

[Badger]

I thought he was working in a Rugby Football Club also. How can one tell if the reference is to a Ring Final Circuit or a Radial Final Circuit . These things seem to creep up on me , last year I was wondering what a MET was and now I have to remember that the Neutral is now Live and they are both called Lines while the Earth wire changes name about 3 times a year .

The best one they ever came up with was to alter the voltage ranges from Low, Medium and High .

Now up to 1000V is Low , :C wonder how much that part had to drink when he thought that one up .??

main earthing terminal ; ) :slap