2.5mm lsf radial from 20a DP switch

[Bigcheese0]

Hi

Im Looking for some advice on compliance as its a bit of a gray area

Kitchen currently has 13a FCU fed from ring main and 2.5mm lsf to single gang skt for washing machine.

Want to change this to

20a DP switch and spur off the single gang socket for washing machine and fit second single gang skt for dishwasher.

Reason for not fitting new FCU and separate supply is its a brand new house and would have to destroy tiles.

I realise the current capacity of the 2.5 is round 20a but the washing machine and dishwasher are no where near pulling that even with both heaters on at same time and taking diversity in to account would imagine it is unlikely to ever have both machines on the heating phase at the same time.

Would this be acceptable ?

 

[Julie.]

Hi

Im Looking for some advice on compliance as its a bit of a gray area

Kitchen currently has 13a FCU fed from ring main and 2.5mm lsf to single gang skt for washing machine.

Want to change this to

20a DP switch and spur off the single gang socket for washing machine and fit second single gang skt for dishwasher.

Reason for not fitting new FCU and separate supply is its a brand new house and would have to destroy tiles.

I realise the current capacity of the 2.5 is round 20a but the washing machine and dishwasher are no where near pulling that even with both heaters on at same time and taking diversity in to account would imagine it is unlikely to ever have both machines on the heating phase at the same time.

Would this be acceptable ?

No, and it isn't a grey area.

Only if the ring is supplied by a 20A mcb/rcbo would it be actually safe, but even so that would still be non-compliant.

Why fit the 20A switch?

If you left the fcu in situ feeding both socket outlets that would be acceptable, although limited to 13A of course.

If you removed the fcu and used a double socket on the spur to supply both loads that would be compliant

 

[Bigcheese0]

Hi

So what your saying is I can run two appliances from a radial 2.5 fed from the fcu 13a fuse to a 2 gang skt.

This is what I mean grey area

The reason for the 20a dp switch is to allow for isolation of the circuit at worktop height.

Both appliances are protected by a 13a fuse on the plug top and the ring main is protected by a 32a rcbo.

So removing the fcu and fitting an un switched connection unit would be fine? And fitting a 2G skt when the skt is rated at 20a, meaning I have no means of isolation.

Yes ideally I would love to run a 4mm back to the board and have 20a rcbo for designated appliance circuit but its not possible at this time and would be a nightmare to do.

So trying to find an acceptable solution without destroying the place

Thanks

 

[Lucien Nunes]

If you want a solution that is universally recognised as compliant, your unfused spur from a 32A RFC must only feed one point. Pragmatically, when the load is two specific installed appliances, it makes no difference to the spur cable or the point loading on the RFC whether they are fed by one double or two single sockets, but the latter is not amongst the compliant configurations of an RFC. However, deliberately using a (compliant) unfused spur with one double socket to feed two high-load appliances is a questionable design choice, regardless of whether the wiring configuration itself is permissible.

The other bottleneck is that 20A switch. Granted, the intended maximum load on a BS1363 double is 20A, but usage at 26A is possible resulting in overload of the switch. Therefore a 32A / 40A / 45A switch would be the choice.

Fusing the spur down with a 13A FCU would be unacceptable in my view and much inferior to the unfused spur. In reality the unfused spur will work just fine and nothing will overheat, whereas the FCU would likely be subjected to periods of low to moderate overload long enough to heat its fuse and contacts beyond their expected working temps. (My washing machine and dishwasher certainly heat at the same time on occasions and hit the 20A.) Although in this case the wiring configuration would appear compliant, the design would surely count as as inadequate hence non-compliant.

 

[timhoward]

Can you get a 2nd cable from worktop height to down below?
If you want to do minimal damage the least invasive and better design might be to stick a dual surface mount 2 gang pattress over the current hole at worktop height and have two 32A DP switches, both part of the RFC.
It would only need a couple of holes with a tile drill to hold it. It still won't look brilliant though as it would be surface mounted.

I'd favour doing some very careful tile surgery with diamond multitool blade and getting another back box in.

 

[Bigcheese0]

Mmm eh would be preferable

I really don't want to supply 2 appliances from a single 13a fcu nor do I want to to blank of the fcu for the w/m.

Removed the kick plate and had a quick look and it appears I can possibly fish a 2.5 down from a 2 gang above where the dishwasher will be.

So 2.5 down to single gang switched skt for D/W but can't get fcu in, so no isolation at worktop acceptable?

Thanks

 

[timhoward]

Is there an adjacent cupboard - switched socket in that and neat hole for plug?

 

[Bigcheese0]

Yes but it's the 600 sink cub so don't think you can have a skt in it? But just to make things worse I'm in Scotland and I believe Scottish building regs require you to have an accessible means of isolation?

 

[telectrix]

socket/s below sinks are fine. a water leak can happen anywhere and wet accessories. water has a tendency to runn across a ceiling several feet, and then soak down the wall to any socket/switch that's in it's path.

 

[littlespark]

In an adjacent cupboard is still accessible.

It’s better than having to move the appliance to get to the plug.

if you need “eyes on” advice, there’s a few member across Scotland if you could give a rough area.

 

[Bigcheese0]

Says up here it's a no go with socket in sink cub, cause nicola says remember I'm in a budding communist country.

Anyway I can't remember but is a 3/4/6 gang mk grid switch frame the same size as a 2 gang skt? as I think I could do away with the skt at worktop height and change it to a single mk grid skt with a mk 20dp dishwasher module switch?

 

[littlespark]

I am “up here” and it’s never been a problem.

MK grid will fit a 3 or 4 switch grid into a 2 gang box…

 

[Bigcheese0]

Well was reading building regs last night and it says you can't? But don't get me wrong I agree with you but hay ho scot build regs got to love em.

I think my idea of putting in a grid swith single skt with single module fcu and single module dishwasher switch would be the way to go and would keep Mrs happy as she would still have a skt at that part of the kitchen

 

[brianmoooore]

Socket in cupboard under sink is absolutely fine.

 

[telectrix]

local to me there's a housing estate built 70's. wylex CU with 3036's, all mounted below kitchen sinks.,

 

[Bigcheese0]

Yes back in the day it was fine but I ain't been on the tools in a long time and not domestically.

So if its acceptable for an EICR to have a socket under the sink can it be fed directly from the ring via 2.5mm radial?

 

[brianmoooore]

Yes back in the day it was fine but I ain't been on the tools in a long time and not domestically.

So if its acceptable for an EICR to have a socket under the sink can it be fed directly from the ring via 2.5mm radial?

Yes, as long as it's a single or double socket, but if it's a double, the question arises as to whether it's acceptable to plug in two appliances with a combined intermittent draw that might exceed 20A.

 

[brianmoooore]

If an occasion occurs where the current draw is likely to exceed 20 A, I extend the RFC into the cupboard into a dual surface box and fit two single sockets side by side

 

[Bigcheese0]

Switched Single socket under sink fed by 2.5mm lsf spured from double socket above w/t.

Would this be OK for an EICR

 

[Strima]

Switched Single socket under sink fed by 2.5mm lsf spured from double socket above w/t.

Would this be OK for an EICR

Is it fed from a ring or radial? What rating is the circuit protective device?