Supply for utility room from upstairs ringmain + a further question

Hi All,

1) I was repositioning a surface mounted twin socket used for washing machine in the utility room (a separate but adjacent room from the kitchen) to a more convenient position on the opposite wall. It has an older type (white) 2.5mm T&E cable. I am chasing the wall to bury the cable under a plastic conduit and intend to fit a new double flush mounted 13a socket. I switched off the downstairs ring main socket supply (32amp CB) at the CU. Just for safety I checked that the power was off with a multimeter but noticed it was still live (reading 243volts). I traced the cable into the loft (its a chalet bungalow, first floor added circa 1977) and found it was spurred from a cable using a junction box (no FCU in the line) presumably from upstairs ringmain, as once this was switched off (also 32amp CB) at the CU the circuit was dead. So the supply for this spur is from upstairs. My question is: a) I know this is not the best scenario, but can I leave this connection as it is or do I have to remove the cable? The work looks 'professionally' done and neat. The socket is intended to supply power to a new fridge/freezer and a washing machine. I intend to label the CU/new socket to state the source of power supply. b) Is this legal?

2) Secondly, in the utility room there was a wall flush mounted old type of broken single 3-pin brown socket (1950s?) which was blanked off (not in use) coming off the downstairs ring main. I am hoping to re-activate this socket by changing it to a modern double socket. But the cable appears to be 1.5mm (older grey cable) which I suspect is the original cable used in this 1950s built house. The cable comes from what looks like an original older junction box and there is also another similar cable coming out supplying a single socket in the study. The incoming supply from the ring main into this junction box is a thicker type of 2.5mm size cable. I feel I need to change the cable from the junction box to the new socket in the utility room for 2.5mm T&E. This is for use on a tumble drier or washing machine. Is this acceptable? Can I have 1 new cable and 1 older cable coming out of the junction box? Altogether I need a total of 3 sockets (including item 1 above) in the utility room to supply a washing machine, new tumble drier and new fridge/freezer. There will not be any new circuits added in this exercise - just updating existing ones.

For info, Consumer Unit has separate circuits for Kitchen hob/oven 32a each, Upstairs sockets, Downstairs sockets 32a each, lighting upstairs, downstairs 6a each, garage 16a, immersion 16a and shower 40amp. Consumer Unit fitted circa 1998.

Any advice offered for the above questions will be much appreciated. Thanks.

Firstly your questions would be best answered by using the correct forum section, which would be Electrics UK.

When undertaking electrical work in a domestic dwelling, legally you need to comply to part p of the building regulations. This would simply mean that things most be done safely and reasonable precautions are taken.
But there is also BS7671 to consider which gives guidance on what is required to comply to certain electrical situations.

Question 1)
You can take an unfused spur of a ring final circuit, but BS7671 appendix 15, does not recommend that a 1.5mm t&e unfused spur is used, a spur of 2.5mm is required, but if the spur was fused at the intersection of the ring final then 1.5mm t&e can be used. But you will require to run 2.5mm from the intersection of the ring to the fused connection unit.
BS7671 will only allow for one single or double socket is taken from an unfused spur of a ring final, you cannot run multiple spurred sockets of a unfused spur, you can of a fused spur though.
Also routing of cables within walls and floors must follow the requirements of using the permitted safe zones or the use of mechanical protected containment of mechanically protected or earth-sheathed cables.

Although taking a socket from the upstairs ring to a downstairs socket, is not ideal, it is not a no no. I would recommend that this is detailed at the consumer unit though and any documentations used under minor works/certification.

As you are relocating a socket and burying cables in walls, the new work and the sockets must have RCD protection (30mA), if it does not already exist.

Question 2)
The above applies, with regards to cable sizes, cable routing/design, spurs and RCD protection.

In my opinion it is not good practice, to have two high output appliances on a double gang socket, they do get hot and are known to overheat and melt.
So I would recommend that single gangs sockets are used on high output appliances, such a washing and drying equipment.

Thanks PrenticeBoyo, appreciate your prompt response.

Apologies for submitting this query to the wrong forum and thanks for redirecting to the Electrics UK forum. A genuine mistake from me!

So this is how I am going to proceed:

Q. 1) There is already RCD protection. As the existing wiring of the double socket already comprises a 2.5mm cable and the supply is taken from upstairs ring main via junction box I will leave the circuit as is. Will label the CU. The only difference being that I will route the same cabling from the ceiling directly and vertically down into the chased wall/conduit (ensuring zonal compliance) to the socket to be used only for a tumble dryer.

Q. 2) Replace the existing old 1.5mm cable with a 2.5mm spurred from the existing junction box via a switched fused connection unit to a double socket for supplying power to a fridge/freezer and washing machine. Therefore it will be: 2.5 mm cable from Junct box > Switched FCU > wall socket. Would it be too much of a load for the 2 appliances on this circuit? The fridge freezer has a A++ rating. This would total 10.5amps to 13 amps on that circuit. Would this be too iffy? FCU protected by 13a fuse.

Thanks once again for your input.

If your installing a fused connection unit, they have a maximum rating 13A. Therefore you will be restricted to a 13A demand on the circuit.
It would be highly likely that on some cycles that W/M is demanding close to 13A. From a fridge freezer I would expect much less, but adding both loads together I would expect it to exceed 13A. So yes Iffy, and would reconsider.

Hi PrenticeBoyo,

Thanks for that. Would it then be OK not to install a FCU as the spur is directly from the ring main via a junction box? I had note that a FCU is not essential in this instance.

Thanks

I would extend the upstairs ring to provide adaquate sockets and power for each appiance.

DS

nunesal said:

Hi PrenticeBoyo,

Thanks for that. Would it then be OK not to install a FCU as the spur is directly from the ring main via a junction box? I had note that a FCU is not essential in this instance.

Thanks

Click to expand...

You can exclude the FCU, providing it is a spur form the ring final and not a spurred spur. 2.5mm t&e will be adequate. But as DS has posted above, extending the ring is better practice, if practicable.

PrenticeBoyofDerry said:

extending the ring is better practice, if practicable.

Click to expand...

Why? What difference does it make - to one socket (single or double)?

deadshort said:

I would extend the upstairs ring to provide adaquate sockets and power for each appiance.

Click to expand...

Each appliance only needs one socket.

EFLImpudence said:

Why? What difference does it make - to one socket (single or double)?


Each appliance only needs one socket.

Click to expand...

It leaves provisions for expansion.

It's the TD and WM double socket, 26a debate ……………………..i was thinking about

DS

Hello DS,

I note your valid concerns. Neither of the two socket will be used individually for W/M and T/D. I have noted elsewhere the 26a situation mentioned as this may be a genuine problem.

In my situation, The T/Dryer will have a separate socket supplied from the downstairs ring (See Q 2 of my query) where I intend to replace the existing 1.5mm cable and single brown socket (old one possibly 1950s) with a 2.5mm cable and a double socket. As PrenticeBoyo has suggested this will be OK as it is not a spur and no FCU. Zonal rules being obeyed.

As for the W/M, the existing socket, to which power is being supplied from the upstairs ring, (see Q 1 on my original query) it is being repositioned and buried in the wall (same cable but different socket, as the original was surface mounted) but here again the supply is from a junction box tapped into the ring but not re-spurred. (I was surprised to discover that the supply was taken from upstairs ring)

Therefore, both the sockets will be directly supplied (and easily accessible in the loft) from each of the 2 rings (one upstairs and the other from downstairs) and will not have a FCU to either of them as this would limit the sockets to 13 amps output each. I need a double socket on one of the supplies to accommodate a fridge/freezer. Do you agree this arrangement is satisfactory?

I note the suggestion from others above, that extending the circuit would be beneficial - good idea too. But the utility room to which these works are being done is very small in size and will just about accommodate the 3 appliances, ie W/M, T/D and F/Freezer and I will have the 2 sockets needed for the purpose.

nunesal said:

I note the suggestion from others above, that extending the circuit would be beneficial - good idea too.

Click to expand...

so your not going to do it that way crack on !

DS

Yes, because I am only repositioning an existing socket with its original cable onto the other side of the wall. The second socket's cable is being renewed from 1.5mm to 2.5mm and the existing old brown 1950s socket renewed.

nunesal said:

Yes, because I am only repositioning an existing socket with its original cable onto the other side of the wall. The second socket's cable is being renewed from 1.5mm to 2.5mm and the existing old brown 1950s socket renewed.

Click to expand...

Is there not another unfused spur wired in 1.5mm to a socket in the 'study' ? This would be non compliant, as you are changing a single socket to a double and are retaining the socket in the study. All fed from a JB which is spurred from ring final.


Kind regards,

DS