1mm attached to a 20A circuit

[vitoboy]

Hi all
EICR today on a ground floor flat .. 1 issue ..
At the consumer unit there was a 1mm core with its yellow (sleeved brown) in a 20A radial circuit mcb ( socket circuit ) and the blue in with its neutral.
When I disconnected it I found it was attached elsewhere to this circuit .. not in a socket we could find ..so presumably in a hidden jb above the ceiling.
So it seems its not carrying load as its not in an accessory and one end is now made safe in a jb by the consumer unit.
Now I know its not protected by the mcb .. but it's not carrying any load ..
Is this deemed safe .. what would you code it.
Many thanks

Vito

 

[westward10]

Your second and third paragraphs make no sense. You presume a hidden joint box yet one end is made safe art a joint box by the DB?

 

[Rockingit]

slightly confused by your post - are you saying that both the L & CPC (sleeved brown) are terminated to the MCB?

Regardless, it’s no longer permissible to use the G/Y for anything other than CPC even with over sleeves so that is an instant consideration irrespective of anything else.

 

[timhoward]

At the consumer unit there was a 1mm core with its yellow (sleeved brown) in a 20A radial circuit mcb ( socket circuit ) and the blue in with its neutral.

I couldn't follow the question earlier but I just read this again after my beer and noticed the words above. Implication is an extra set of conductors.

Are you saying there's a radial circuit connected to the 20 amp MCB.
AND additionally there is this extra 1mm cable tucked into the MCB and the N bar?

Then you disconnected the 1mm cable at the CU and put it in a joint box?
But you don't know where the other end of the 1mm is connected to?

If that is all correct, pertinent questions are
-what size are the other conductors in the MCB that you left there.
-have you discovered any purpose at all for this circuit? (EDIT Just seen you said socket circuit)
-is it 3 core cable in old colours (red, yellow, blue)?

Tell us a bit more

 

[nicebutdim]

I suspect we'll never know.

 

[westward10]

Welcome to our world, can you do EICRs, yes, er no.

 

[vitoboy]

I couldn't follow the question earlier but I just read this again after my beer and noticed the words above. Implication is an extra set of conductors.

Are you saying there's a radial circuit connected to the 20 amp MCB.
AND additionally there is this extra 1mm cable tucked into the MCB and the N bar?

Then you disconnected the 1mm cable at the CU and put it in a joint box?
But you don't know where the other end of the 1mm is connected to?

If that is all correct, pertinent questions are
-what size are the other conductors in the MCB that you left there.
-have you discovered any purpose at all for this circuit? (EDIT Just seen you said socket circuit)
-is it 3 core cable in old colours (red, yellow, blue)?

Tell us a bit more

Hi Tim
Yes .. an additional 1mm 3 core cable (old colours) was connected in a 20A mcb with a socket radial circuit... the blue was connected in the neutral bar with that circuits neutral.
The original radial socket circuit was wired in 2.5 t&e.
I disconnected the 3core from the dB..( it was to small to be on a 20A mcb ) ..but following disconnecting it I found it still became live when the original redial circuit was switched on.

Somewhere I can't see .. it is connected to the 20A radial circuit.. presumably in a joint box above the ceiling.

The 1mm 3 core does not appear to be under load ( it's not present in any sockets) it seems to just go from a joint box back to the dB.

So it's not in danger from overload .. as there is no,load on it .. but as a 1mm its not protected by the 20A mcb.

How would you code this.?.. thoughts?

 

[westward10]

So you have a 2.5 and 1.0 on a single mcb?
You disconnect the 1.0 but when you switch it back on it becomes live?

 

[timhoward]

Thinking about why 3 core might have been involved, e.g. smoke alarms, light switching, bathroom fan, or heating wiring / wall stat

Here is a total stab in the dark. Maybe a boiler was upgraded, a wall thermostat was no longer required and removed, and someone wanted somewhere to shove the wires, and they knew enough to know that the old boiler was on a fused spur on that circuit and to them it seemed the logical place to put them.
Is there an airing cupboard with a wiring centre in it?

 

[vitoboy]

Thinking about why 3 core might have been involved, e.g. smoke alarms, light switching, bathroom fan, or heating wiring / wall stat

Here is a total stab in the dark. Maybe a boiler was upgraded, a wall thermostat was no longer required and removed, and someone wanted somewhere to shove the wires, and they knew enough to know that the old boiler was on a fused spur on that circuit and to them it seemed the logical place to put them.
Is there an airing cupboard with a wiring centre in it?

Yes .. my thoughts exactly..there has been a new boiler and heating system fitted ..but previously there was no heating system and just a immersion for hot water .
Maybe in the distant past (1960s building) there was a back boiler and this a stat wire .. but no trace of any of this within existing fittings now .. maybe a wiring center buried in the fabric of the building somewhere.. but no trace of this we could fine .. we were there for 6 hours for this eicr .. electrician and mate .. we gave it a good going over.
The building is a 1960s ex council built looks like concrete slab ground floor with timber upstairs .. we are working on the ground floor only as its a 2 bed flat with another 2 bed flat upstairs... both are now privately owned.
So this is why I'm asking your opinions.. its potentially major work to find where this 1mm is joined to this 20A radial circuit.. is it a c2 .. or a c3 .??
I do a lot of EICRs.. we don't rush them .. but this is a new one for me.

 

[vitoboy]

Yes .. my thoughts exactly..there has been a new boiler and heating system fitted ..but previously there was no heating system and just a immersion for hot water .
Maybe in the distant past (1960s building) there was a back boiler and this a stat wire .. but no trace of any of this within existing fittings now .. maybe a wiring center buried in the fabric of the building somewhere.. but no trace of this we could fine .. we were there for 6 hours for this eicr .. electrician and mate .. we gave it a good going over.
The building is a 1960s ex council built looks like concrete slab ground floor with timber upstairs .. we are working on the ground floor only as its a 2 bed flat with another 2 bed flat upstairs... both are now privately owned.
So this is why I'm asking your opinions.. its potentially major work to find where this 1mm is joined to this 20A radial circuit.. is it a c2 .. or a c3 .??
I do a lot of EICRs.. we don't rush them .. but this is a new one for me.

Ps ..Smokes wired from the lighting circuit

 

[HappyHippyDad]

Unsatisfactory report due to FI required.
I couldn't really understand most of the OP's posts though, so could well be a C2.
Could be anything actually due to lack of coherent info.

 

[timhoward]

To be fair to the OP this is a rather unusual situation.

My opinion based on what we know-
FI? Well the only thing we don't know is where it connects, and OP has done his best to determine there are no accessories downstream of the joint.
C1? No one is one single action away from danger
C2? As it's left the cable can't be used by an ordinary person, so hard to say that it's potentially dangerous.
C3? We'd definitely recommend improvement. Ideally if redecoration ever permits it the joint would be found and dealt with.

I think I'd C3 it.
(I might stick an FCU with 5A fuse on the end of it with a 5A Max label, then I'd feel that I'd done all I can to prevent anyone overloading the cable in future. )

 

[pc1966]

C3 would seem most appropriate (as 1mm can clear 20A MCB adiabatic under fault conditions), but it is clearly an odd situation to be still live from the far end without any obvious connection point.

 

[vitoboy]

To be fair to the OP this is a rather unusual situation.

My opinion based on what we know-
FI? Well the only thing we don't know is where it connects, and OP has done his best to determine there are no accessories downstream of the joint.
C1? No one is one single action away from danger
C2? As it's left the cable can't be used by an ordinary person, so hard to say that it's potentially dangerous.
C3? We'd definitely recommend improvement. Ideally if redecoration ever permits it the joint would be found and dealt with.

I think I'd C3 it.
(I might stick an FCU with 5A fuse on the end of it with a 5A Max label, then I'd feel that I'd done all I can to prevent anyone overloading the cable in future. )

Thank you Tim.. this was my feeling.