Cooker cable

Hi guys, 

Recently refurbished living room needed a socket grind the tv to plug in. I installed a new socket house in the wall and went up in the loft to drill a hole on the wood beam and send a 20A power cable down to the new socket. The other end needed to be terminated into an existing power cable in the loft. I found the cooker thick cable so I cut it and terminated these with a junction box. The oven cable is 32A the spur of the new socket is 20A. There is no other devices on this line. The cooker cable comes straight from the fuse box into the cooker in the kitchen. Did I make a stupid thing with terminating the cooker cable into a smaller cable towards a tv socket? Please help me. It’s been working fine over 6 months. Just recently thought it through maybe I didn’t do it right so I should redo it. I would appreciate any thoughts and comments. 

Hi guys, 

Recently refurbished living room needed a new socket behind the tv. I installed a new socket house in the wall and went up in the loft to drill a hole on the wood beam and sent a 20A power cable down to the new socket. The other end needed to be terminated into an existing power cable in the loft. I found the cooker thick cable so I cut it and terminated these with a junction box. The oven cable is 32A the cable of the new socket is 20A. The cooker cable comes straight from the fuse box into the cooker in the kitchen. Did I make a stupid thing with terminating the cooker cable into a smaller cable towards the tv socket? Please help me. It’s been working fine over 6 months. Just recently thought it through maybe I didn’t do it right so I should redo it. It is an 8 years old new built property. I am not an electrician. I would appreciate any thoughts and comments. 

What size is this "20A cable" you talk about? by that I mean what is the cross sectional area of the cable and what type of cable?

I think, as you would expect, that connecting a socket to a heavily loaded circuit with the wrong size cable and no testing is not going to get you a major round of approval.

It would work and might not overload but it is not a well designed solution.

Cooker circuits, depending on the cooking equipment connected could be carrying a large current and adding more load to the circuit makes it more likely the circuit breaker will trip.  

If the cooker circuit is 32A and the cable you have installed is designed to carry less than this load then the cable could be overloaded and cause a fire.

The practical observed dangers would depend on the loads connected but it is not a circuit that could be designed safely in accordance with the wiring regulations.

Another thing to clarify, is this an "cooker" cable (oven and hob) or just an "oven" cable?  That will make a huge difference to the load on it already.

Is this a bungalow? I can’t see how a cooker cable would be in the loft? So if a cooker cable was in the loft did you not think to find an existing socket power cable in the loft and join to that or was your decision on a first come first joined basis? 

This is where limited knowledge is dangerous. You should have sought advice prior to carrying out the work. 

I'm getting a feeling of deja vu  here 

What do you mean Evans? 

This is only the cooker circuit. The hob is gas. 

It is a coach house type flat. Cars under and no one above. There was no socket cable running around that area only lights. I did not want to mix up lights with tv socket. I thought a very thick cable can be more safer to terminate another one in. Would it be more safe if I replace the socket cable the same thickness as the cooker cable? So there would be no differences between. The socket would get the same thickness 32A. Any thoughts?  

What sort of junction box have you used? What current is it rated at?

Not an ideal set up you have created and there's a risk of overheating in your junction box if your terminations aren't tight, you have created a weak point in the circuit which will increase the risk of fire.

In principle you may not have done anything "wrong" but still waiting to find out what this "20 amp" cable is that you have used.

As long as the junction box is rated for both the cable size and current then that is not an issue (the average round 32A junction box will almost certainly NOT be rated for the cooker sized cable) And as long as the junction box remains accessible if it has screw terminals.

A spur to a single socket is allowed from a 32A circuit, even connected directly to the origin in the consumer unit.

There is also the question of rcd protection. You have buried a new cable in the wall, so it will need rcd protection. Depending how old the property is, the existing cooker feed may or may not have an rcd.

I used a Prysmian 2.5mm cable from B&Q and used an accessible junction box with screws inside. I think it is 35A rated. I can change this to a 60A junction box? Should I install a fuse on the socket spur? 

ProDave said:

In principle you may not have done anything "wrong" but still waiting to find out what this "20 amp" cable is that you have used.

As long as the junction box is rated for both the cable size and current then that is not an issue (the average round 32A junction box will almost certainly NOT be rated for the cooker sized cable) And as long as the junction box remains accessible if it has screw terminals.

A spur to a single socket is allowed from a 32A circuit, even connected directly to the origin in the consumer unit.

There is also the question of rcd protection. You have buried a new cable in the wall, so it will need rcd protection. Depending how old the property is, the existing cooker feed may or may not have an rcd.

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It is Prysmiam 2.5mm cable from B&Q. Just went to buy an ES A-box IP54/65 rated up to 41A. I am going to install it tomorrow. Anything else you guys think I should make to secure this spur and the whole circuit please tell me. The property is 7 years old I am sure the cooker circuit has a protection. 

I would use a junction box like this https://www.tlc-direct.co.uk/Products/AAJB60.html

At least you know it is rated by the manufacurer for the cable size.

Most 32A junction boxes are only rated for three 2.5mm cables.

Ati said:

ProDave said:

I would use a junction box like this https://www.tlc-direct.co.uk/Products/AAJB60.html

At least you know it is rated by the manufacurer for the cable size.

Most 32A junction boxes are only rated for three 2.5mm cables.

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Thank you Dave. I really appreciate your help. I’ve fitted the new junction box this morning. It should be all right. The cooker circuit has an RCD 80A protection plus an MCB B32. The fuse box is Wylex. The cocker cable is 6mm and my spur is 2mm towards the TV. Now I used the IP54/64 junction box 41A  and rated up to 6mm cables. Hope it is not going to ruin my home. Thanks again everyone for your help. 

It sounds like you now have a safe design. The arrangement is unconventional but compliant.

So long as you have connected the cables correctly and securely then this design is safe.  Testing of the RCD to ensure it works and the cable to ensure it is correctly connected and undamaged would be ideal, but this is much better than your original arrangement.

Duplicate question in different forums merged.

DOC H