Patching in 10mm² cable

[Softus]

Situation:

Triton 10.5kW shower supplied by 10mm² T&E cable, in a rented property.


Observations:

1) The CU appears to be a Wylex unit, converted from rewireable carriers to MCBs. Don't know when. The carrier for the MCB supplying the shower (dedicated) is not pushed right in, and one of the legs is bent.

2) The insulation on the phase conductor, very close to its connection fromthe MCB at the CU, has clearly melted at some time in the past.

3) There is clear evidence of corrosion at the screw down terminal on the MCB carrier.


Questions:

1) As a competent and cautious plumber, am I legally permitted to remedy this problem?

2) Is it better to wrap adequate insulation around the melted section, or to replace the damaged section of the phase conductor with a short section of new cable?

3) If the latter, then is this the right thing to be using (although the rating seems to be for a maximum of 6mm² cable).

I'd be grateful to hear from any experienced electrician.

 

[Pensdown]

1.Unless the worlds gone completely bonkers – Yes

2.You need to cut back the burnt section of cable as the copper will have become annealed and will never tighten in the terminal. If the problem was due to the bad MCB connection it may have damaged the CU connection terminal. You could try cleaning the terminal but if the MCB plug-in connections are soft and look like one of your pipe joints then it’s curtains for the CU.

3.Your right, the yellow crimps are for 6mm cable. Try to find some slack on the cable and pull it into the CU as joining 10mm means choc block or as far as I know un-insulated crimps (special tool) and heat shrink

Have fun
Andy

 

[Adam_151]

1) The CU appears to be a Wylex unit, converted from rewireable carriers to MCBs. Don't know when. The carrier for the MCB supplying the shower (dedicated) is not pushed right in, and one of the legs is bent.

What size is the main switch?, if its 60A then the unit will not be designed to take circuits over 30/32A amp, and its designed not to accept bigger, however, brute force and ignorance will result in an incompatable protective device sat kinda awkwardly twisted to the side... (and so not only do you have the original problem of it not being designed for the current, its probably a bad connection becuase its twisted...)

2) The insulation on the phase conductor, very close to its connection fromthe MCB at the CU, has clearly melted at some time in the past.

Probably due to heat from either the issue above, or an loose screw terminal


Considering the probable inadequacy of the CU to support the shower and the damage it appears to have sustained on that fuseway, the best course of action most likely involves a separate shower CU henley blocked onto the tails http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331829&ts=77810&id=42858



Questions:

1) As a competent and cautious plumber, am I legally permitted to remedy this problem?

I dunno, I epect the answer depends on what exactly you do in the way of fixing it, but anything is better than leaving it how it is

2) Is it better to wrap adequate insulation around the melted section, or to replace the damaged section of the phase conductor with a short section of new cable?

Depends how bad it is, if the insulation is just a tad soft then yes, but if the copper has (as I expect) started to change colour and stuff, better cut it back

3) If the latter, then is this the right thing to be using (although the rating seems to be for a maximum of 6mm² cable).

No, that as you say if for a max of 6mm, you need a 10mm crimp and they only come un-insulated, so you'll need a different crimping tool and will need to heatshrink the joint

I'd be grateful to hear from any experienced electrician.

Well I can't claim to be one of those yet, but I hope my post is useful

 

[Softus]

Thanks to you both for two marvelously clear and informative replies.

I'll check the rating of the CU, and I can see myself engaging an electrician if a separate CU is needed.