Untraceable/unknown circuits

[Octopus]

If you can't 'trace' them then you shouldn't be doing an EICR.. or changing a CU for that matter. It's not a codeable thing. If you don't know where a circuit goes or what it is for, how is this a C3? How does it not comply with the current regs??

What rubbish, I couldn't disagree with you more - C3 requires investigation.

There are tens of thousands of houses around with untracable circuits in them. On an EICR its a C3, on a board change you can either leave the cable "safely" within the board or connect it to e MCB with the same rating as the old board and the MCB switched off.

Did one myself about 6 months back, EIC stated unknown as circuit description and as the owner was a retired engineer we discussed the options - we agreed to connect the cable to the MCB and leave it switched off. 2 months later got an email saying he had found what the circuit did and I duely went round and tested said circuit.

Maybe I've got the wrong end of the stick, BUT a RCD board with 1 unknown circuit in it is far, far safer than a BS3036 board with no RCD's

 

[ajl_02]

Exactly!!! The old board with no rcd protection had been used with no problem for about 30 years. The board now has rcd protection on all circuits so its gota be a lot safer than it was!!

 

[plugsandsparks]

What rubbish, I couldn't disagree with you more - C3 requires investigation.

There are tens of thousands of houses around with untracable circuits in them. On an EICR its a C3, on a board change you can either leave the cable "safely" within the board or connect it to e MCB with the same rating as the old board and the MCB switched off.

Did one myself about 6 months back, EIC stated unknown as circuit description and as the owner was a retired engineer we discussed the options - we agreed to connect the cable to the MCB and leave it switched off. 2 months later got an email saying he had found what the circuit did and I duely went round and tested said circuit.

Maybe I've got the wrong end of the stick, BUT a RCD board with 1 unknown circuit in it is far, far safer than a BS3036 board with no RCD's

Agree, when you are doing Comm and industrial i have had many issues tracing ccts, even with the help of the site based electricians, they dont know either. Its the nature of the beast.
As for the OP, nearly all old houses had an immersion heater cct but often these are redundant with combis, that may be one of them ....

 

[infinity]

^^^ Agree with Murdoch, in older installs especially comm industrial you will usually always have at least one circuit you spend over 30mins looking for until you have to move on. I'd be very surprised if you have been carrying out EICR's and always found every single circuit on older installs?

C3 - further investigation

 

[Steve_P]

These aren't a cooker and heating circuit with a 100mA time delay RCD main switch are they?

 

[kingeri]

All I meant was not knowing what a cable does isn't in itself a C3. What reg no. would you quote?

 

[High Tower]

Murdoch, thank you!!!,

Gentlemen it's not a ideal world, never will be!, there will always be unknown circuits!

I do the same as Murdoch says, I change the board and put cables in place but do not connect.

And I second that a rcd and a mcb will always be a drastic improvement on 3036's.

 

[HandySparks]

All I meant was not knowing what a cable does isn't in itself a C3. What reg no. would you quote?

At the least, 514.1.1 and 514.1.2 regarding labelling of switchgear and wiring will apply. 514.1.2 says: "So far as is reasonably practicable, wiring shall be so arranged or marked that it can be identified for inspection, testing, repair or alteration of the installation."

If you can't work out what it does, it's clearly missing labels, diagrams or schedules.

 

[Jerry H]

Upon testing an installation after a fuse board change there are 2 x circuits which ate untraceable. I have left them connected but was just wondering if these circuits would be noted down in the departures from bs7671 box on the install cert??

Have just finished a CU change on a 1960's house. There were several 'unidentifiable' circuits but we made an effort to trace them. One was an old electric clock point plastered into the wall by the fire place, another was an old electric bathroom heater and a third was some sort of weird gizmo in the loft that was supposed to stop the water pipes firing up. If you can't find them, don't connect them. They'll soon let you know when things don't work

 

[richy3333]

If you can't 'trace' them then you shouldn't be doing an EICR.. or changing a CU for that matter. It's not a codeable thing. If you don't know where a circuit goes or what it is for, how is this a C3? How does it not comply with the current regs??

Labelling?

 

[marcusone]

If I can't trace a circuit within a reasonable time I explain to client that I can continue hunting it down at x pounds per hour or leave it disconnected until they find something not working. They always opt for disconnection as the cheaper practical option. Best endeavours gentlemen.

 

[baldelectrician]

Had one today

Found 2 circuits out of 11 redundant, spent a good 45 mins checking all stuff was working (inc client moving wardrobes to get into little used sockets etc).

In the end all circuits worked and tested OK, the 2 redundant ones were disconnected and terminated inside the consumer unit incase something turned up.

In the end the client was happy- the CU was changed 8 years ago and these 2 circuits were reconnected without testing

 

[oldtimer]

Had one today

Found 2 circuits out of 11 redundant, spent a good 45 mins checking all stuff was working (inc client moving wardrobes to get into little used sockets etc).

In the end all circuits worked and tested OK, the 2 redundant ones were disconnected and terminated inside the consumer unit incase something turned up.

In the end the client was happy- the CU was changed 8 years ago and these 2 circuits were reconnected without testing

Had the exact same and did the exact same terminated cables into connector strip labelled them job done even highlighted it on the EIC plus I could sleep at night know I did no harm and if the customer phones me in 3 months time and say I knocked those built in wardrobes down and found a twin socket behind them then its a 5 minute job to connect it up but I would not like the H&S people knocking on my door to say my customer died knocking his built in wardrobes down as he touched a cable that he found coiled up behind them.

I have said this before on this forum so I will repeat myself again and will take the flack I find this type of post as a no brainer but the fact the OP has left them connected makes me wonder what type of people we are producing so the lesson is here if you cannot confirm then leave it disconnected I wont mention common sense because there does not appear to be any kicking around on this forum

 

[amlu]

had 2 6mm cables on last CU upgrade. one for cooker, yeah no problem, another one showing 30ohms insulation resistance.
after couple hours of bashing floors found it feeding a socket on another side of property, then 1.5 cable spurred of it into a junction box, for boiler and fridge supply. sic!

 

[PEG]

Surely an unidentified circuit reconnected to a new CU is crying out for one of those new stickers the CU manufacturers send out with every new CU? You know,the one with the big question-mark on it :tt1:

 

[moose]

LMAO and you have to follow the manufacturers by the BGB so one for the ? and oooops its not my fault that wall was live it was the manufacturer, Not sure it will hold any ground in the courts, but have you all noticed these cables are always clear nothing connected and its always there.....

 

[thekingiam]

can't believe you have connected what sounds like a disconnected circuit!
go back please and disconect it, if everything still works leave it disconnected.

 

[Brendan976]

Borrow a tone generator,disconnect from consumer unit, connect generator to the now disconnected ends, turn on to constant tone, now trace where the cables go the louder the tone means the closer you are.
Ben

 

[PEG]

Borrow a tone generator,disconnect from consumer unit, connect generator to the now disconnected ends, turn on to constant tone, now trace where the cables go the louder the tone means the closer you are.
Ben

That's the spirit,Ben,proper use of correct gear but it appears the suggestions of oiling the bolt have arrived a while after the horse left...

 

[Brendan976]

You never know it may help someone else who comes across a similar situation in the future. Or the original op gets a repeat bit of work at the same premises.

Ben