Supply for utility room from upstairs ringmain + a further question

[PrenticeBoyofDerry]

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.

I believe the OP has stated in first post, that the original socket is broken and being replaced for DG one.

But a point that has yet to be established, is the accessibility of the junction boxes as a MF joint maybe required.

 

[deadshort]

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?

DS

 

[nunesal]

Hello PrenticeBoyo and DS,

Please bear with me and no offence intended in ay manner as I am seeking your valued advice.

You are right Prentice, the broken 1950s single socket is being replaced for a double. I can confirm that access is not a problem via a hatch as the JBs are in the loft above the utility room (ground floor utility, no storey above and it is a pitched roof) for MF (?) joint.

DS: What you are stating is that I cannot fit a double socket but only a single one despite replacing the 1.5mm cable for a 2.5mm cable?
So, how about me replacing the 2.5mm cable anyway (access no problem) to a single socket (instead of double) then spur a connection off it to another single socket via a switched FCU for supplying power to the fridge? Is that acceptable? You are right in that there is an offtake to the study from the junction box from where the supply was for the old single socket (the one I am replacing). The line to the study is 1.5mm similar to the one I intend replacing to supply the utility socket.

Thanks

Nunesal

 

[EFLImpudence]

I am not sure where the confusion has arisen but -
this is the informative diagram in the regulations.
It is not exhaustive and does not preclude other compliant arrangements.

Note the top left:

 

[deadshort]

EFLimpudence has provided all the info you require

DS

 

[PrenticeBoyofDerry]

I think the confusion is that the OP, is intending to take two unfused spur legs, directly from the same junction box from the origins of the ring, to supply one single socket outlet on one leg and a DG socket outlet on the other.

I personally do not see an issue with this electrically, providing the JB is rated correctly.

 

[PrenticeBoyofDerry]

for MF (?) joint.

MF means "maintenance free" Cable joints/junctions, in areas that are not accessible, require to by manufactured in this method.

 

[nunesal]

I think the confusion is that the OP, is intending to take two unfused spur legs, directly from the same junction box from the origins of ring, to supply one single socket outlet on one leg and a DG socket outlet on the other.

Spot on PrenticeBoyo. The set up is already in place except that I was intending to replace the 1.5mm of one leg with 2.5mm (for safety) + DG socket for the utility room and leave the other one as is.

I personally do not see an issue with this electrically, providing the JB is rated correctly.

I will check the existing socket (orginal installation brown in colour) to see if it is of correct rating. If not I will change it for a modern one.

Referring to EFLImpudence's circuit arrangement diagram, the top left is what I have except that mine has 1.5mm cable. The diagram shows a single socket. As an alternative, I could use the same arrangement with 2.5mm cable and take a spur using a FCU (switched if needed) from the single socket to another socket for the fridge. Or can a double socket be used in place of single as shown in the diagram? Personally, I feel the PrenticeBoyo's agreement (above) would be easier to accomplish. Agree?

Thanks

 

[PrenticeBoyofDerry]

I will check the existing socket (original installation brown in colour) to see if it is of correct rating. If not I will change it for a modern one.

It is the junction box that needs to be looked at, you have already stated that this socket is damaged and must be replaced.

The diagram shows a single socket. As an alternative, I could use the same arrangement with 2.5mm cable and take a spur using a FCU (switched if needed) from the single socket to another socket for the fridge.

The diagram does not show an unfused spur to a socket, then a FCU downstream of that to a second socket. That set up does not meet the guidance of appendix 15.
The FCU should be at the origins of the ring, not downstream of an unfused spurred socket.

Or can a double socket be used in place of single as shown in the diagram?

A double socket can be used, but as we have already mentioned previously, it is unwise for two high output appliances to be plugged into a dg socket.

 

[nunesal]

Hi PrenticeBoyo,

It is the junction box that needs to be looked at, you have already stated that this socket is damaged and must be replaced.

Agreed, my mistake/typo. I meant to say JB - to repeat, it is the Junction Box I need to look at.

I think the confusion is that the OP, is intending to take two unfused spur legs, directly from the same junction box from the origins of the ring, to supply one single socket outlet on one leg and a DG socket outlet on the other.

I personally do not see an issue with this electrically, providing the JB is rated correctly.

Referring to your above comment, if I use a DG socket outlet on the other leg (with a new 2.5mm cable) and with the original JB from the ring being correctly rated, I would still be restricted to one 'heavy' appliance (either W/M or T/Dryer) and no addition of a fridge/freezer to the JB outlet with either one of the 2 appliance combination. I'll have to go back to the drawing board and rethink the design unless there is another option. Extending the circuit as suggested previously would be the way forward, but access is very very restricted.

Incidentally, on checking the RCD rating, I notice I have a GE V/304-0291 660475 which is a 100mA unit. I recall in 1998 our sparky changed a new RCD during a house extension because it tripped whenever a light bulb blew or if there was thunder/lightning. The house earthing point was also too close to a electricity overhead cable pole located in our garden (1 foot away from the pole). He said it was too sensitive and replaced with this present one. Not sure if original was a 30mA, but I doubt it. In your earlier message you mentioned a 30mA RCD was needed. I know the regs have changed since 1998, so is this 100mA a no no? I will have to get a sparky in to replace if this unit is out of compliance.

Thanks for your help.

 

[PrenticeBoyofDerry]

I assume your earthing arrangement is via an earth rod/electrode?
They do require to be protected by at least 100mA. But now or since 2008, it is requirement that any newly installed sockets require 30mA and and in most occasions any newly buried cable.

We have already discussed having washing machine and fridge freezer on a 13A supply, it would be acceptable to have W/M and F/F on a double socket.


With regards to the Junction box and the two spurs, you could if you wished, break into the ring again. I am unsure of the proximity of the DG and SG socket to each other, but as you had suggest running them both from the same unfused spur then adding a FCU. I cannot be that difficult to extend the RFC??

 

[deadshort]

Saint PBD !

DS

 

[PrenticeBoyofDerry]

 

[deadshort]

Shaken, but never stirred !

DS

 

[nunesal]

Thanks for your help and patience PrenticeBoyo (Saint). Much appreciated.

The earthing method is via an earth rod. As I am burying the same existing cable in an condiut from the currently surface mounted method and adding a new socket I will arrange for a sparky to undertake the renewal of RCD to a 30mA version.