Single fushed socket to double?

[Delicatedave]

I want to fit a water heater under the sink 240v

My kitchen is rather limited for sockets but the washing machine next to the sink has a single fused socket.

Can I just replace the single socket for a double? Wouldn't this just be the same as putting an extension lead in and using that?

[ProDave]

In principle yes, but I would want to know where the present socket is fed from first. e.g it may come from a 20A DP switch above the worktop so running the WM and a water heater would overload that.

[Jeremy Harris]

48 minutes ago, Delicatedave said:

I want to fit a water heater under the sink 240v

My kitchen is rather limited for sockets but the washing machine next to the sink has a single fused socket.

Can I just replace the single socket for a double? Wouldn't this just be the same as putting an extension lead in and using that?

 

 

Yes, most probably.  Depends on how that socket is wired and the way other outlets are wired on that circuit though, as it's not unknown for DIY changes to have been made that aren't safe. 

 

If there's only one cable in the back of the outlet, then that indicates that it's most probably a spur off the ring.  There's no problem with changing this to a twin gang outlet, just a matter of isolating the supply, checking the wires are truly dead and changing the outlet over.  Only thing to watch is that the supply to that spur is really coming directly from the ring.  If not, then further investigation needs to be done.

 

If it's wired as a part of the ring final, then there's no problem at all, either.  You can often check this by looking to see the number of cables coming in to the rear of the outlet, if there's two, then that's a good indication that it might be part of the ring, although this isn't foolproof, if there's been some amateur electrical work done.  Easy enough for an electrician, or someone competent with the right test gear and knowledge, to check whether or not two wires feeding an outlet are part of a ring or not, though.

 

The reason for checking that two cables coming in are really a ring is because it's possible that someone has fed another spur from an existing spur.  This could then result in the cable current rating being exceeded if the mid-point single is changed for a double.   It's something I've seen done, most commonly in kitchens where additional spurs have been added for washing machines, tumble driers, etc.  Two 13 A outlets are usually[^1] OK on a single 2.5mm² T&E cable, as it will be typically rated at 27 A in many situations.  More than two outlets from a single 2.5mm² spur could potentially exceed the cable rating with high current appliances, and even two outlets may exceed the cable rating if it's buried in the wall.

 

^[1]  Assumes that the cable is clipped direct. 

[Ferdinand]

Products like this from Wickes save you making the bigger hole

 

https://www.wickes.co.uk/Wickes-Converter-Kits---White-Single-to-Double-Socket/p/710075

 

(Information not Recommendation]

 

F

Edited February 23, 2020 by Ferdinand

[ProDave]

2 minutes ago, Ferdinand said:

Products like this from Wickes save you making the bigger hole

 

https://www.wickes.co.uk/Wickes-Converter-Kits---White-Single-to-Double-Socket/p/710075

 

(Information not Recommendation]

 

F

But that won't stop you overloading a cable or switch so is no substitute for checking what you have first.

[Onoff]

Be careful. My mate had a conservatory with just a single gang socket as a spur off a ring. His plan was to run new sockets around and make this new loop part of the ring.

 

He then called me to come and make all the faceplates off. By now it was fully decorated.

 

He'd forgotten to take a return leg up into the loft.

 

After telling him how to do it properly I had the arse so just changed the single gang socket for a dual box and put a 13A fcu up front protecting the 10, 12 whatever doubles he's put in. 

 

His wife complained recently the 13A fuse blew one time! ?

Edited February 23, 2020 by Onoff

[Jeremy Harris]

The kitchen in our old house had two singles and a double daisy chained from one spur off the ring when we bought it.  Luckily, the last single in the chain was just the igniter for the gas cooker and the one before that was just the cooker hood, but the double at the start of the spur had the dishwasher and washing machine plugged in.  Can't understand why whoever did it just wired these as a long daisy chained spur, as it was dead easy to just break the ring and add them to it, needed about two feet of cable and didn't even mean chasing up the wall, as there was a buried bit of rectangular trucking behind the tiles that led down below the worktop (not ideal, as it wasn't deep enough, but there was only about 150mm of it).

[Delicatedave]

I've added and changed sockets before in others houses. I've just never swapped a single socket for double that has fused isolation. The wiring should be ok but I'll double check where in fact this is coming. It's only temp as we want hot water for the sink. The whole kitchen will be ripped out this year, once the roof, the drainage, the insulation is done ?

[ProDave]

26 minutes ago, Delicatedave said:

I've added and changed sockets before in others houses. I've just never swapped a single socket for double that has fused isolation. The wiring should be ok but I'll double check where in fact this is coming. It's only temp as we want hot water for the sink. The whole kitchen will be ripped out this year, once the roof, the drainage, the insulation is done ?

When you say it has "fused isolation" do you mean it is fed from a switched, Fused, Connection, Unit?

 

If so what you propose will be safe, but don't be surprised if the fuse blows when you have the washing machine and water heater on at the same time.

[Onoff]

Has it got a fused connection unit above the worktop, maybe on the kitchen ring, switching the single socket below?

[Delicatedave]

41 minutes ago, ProDave said:

When you say it has "fused isolation" do you mean it is fed from a switched, Fused, Connection, Unit?

 

If so what you propose will be safe, but don't be surprised if the fuse blows when you have the washing machine and water heater on at the same time.

Ok, here's what I mean, bottom is the single socket which we use for the washing machine above it is the fused isolation switch.

[Onoff]

Belt and braces. If the fcu is on the ring replace with a 20A DP switch...then put another next to it both in a dual box. No real worries about that single 13A fuse popping. You could do the drops in 1.5 or 2.5.

 

Gives isolation to each appliance. No need for a fuse anywhere but in the plug. No need for the sockets to be switched. You can get 20A DP switches marked "Water Heater" and "Washing Machine"

 

 

 

[Onoff]

I've an original 2G socket here on a spur off the ring. Runs the dishwasher and washing machine. 

 

Gets a bit warm if SWMBO attempts to use it for the washing machine AND hot tub despite me keep telling her! 

[Jeremy Harris]

12 minutes ago, Onoff said:

I've an original 2G socket here on a spur off the ring. Runs the dishwasher and washing machine. 

 

Gets a bit warm if SWMBO attempts to use it for the washing machine AND hot tub despite me keep telling her! 

 

 

My experience is that it's always the plug that gets warm, rarely ever the cable.  Cable ratings are pretty conservative, and it needs a high load for a long time to get the cable a bit too hot, not something that's likely to happen with the short load duration from something like a washing machine or dishwasher.  The weakest point is usually the fuse in the plug getting hot under high load, which then overheats the line pin, which in turn overheats the contacts in the outlet, causing them to reduce the spring contact force on the pin, adding to the problem.