immersion heater and shower pump off single circuit

[currykid]

Hello,

I need a bit of advice please.

I have a 3kW immersion heater on my hot water cylinder, which is on a dedicated 16A circuit.

I want to put a shower pump in the airing cupboard and am looking to use the immersion heater supply to power it.

I know that I can't run the immersion heater and the pump at the same time as the immersion heater will pull 13A and the pump 5A.

Option 1 is to disconnect the immersion heater altogether. We have been in the house for 8 years and have never used it...

Option 2. A DPDT switch could be used to send power to one or the other, but never both. But I can't find like an MK one, mounted on a UK wall plate. Has anyone come across a DPDT switch as a single mains wall switch ?

Option 3. The other idea I had was to use a non-standard mains socket, such as this: http://www.mkelectric.com/en-my/Pro...socketoutlets/Nonstandard/Pages/K1257WHI.aspx

As the immersion is 13A and the pump 5A I don't see why I can't just use a fused plug on each. By using a non-standard plug and socket it protects against someone using an extension lead to power both at the same time.

Thanks in advance for your help !

Cheers
Chris

 

[PrinceofDarkness]

Chris, there's been a great deal of misunderstanding in the industry over this dedicated immersion circuit business. The original intent of the Regs back in the 70's/80's was that an immersion heater should not be connected to a socket circuit (which was quite common practice in the 60's).

It certainly wasn't the intention that immersion radial circuits should be exclusive to that heater alone. The IEE tried to make that quite clear almost thirty years ago.

What you have there, is an ordinary 16A radial circuit - so you should use it to its full. I doubt very much that that 5A pump actually takes 5 Amps when running (for a very short period at a time). I suspect that the 5A is the recommended fuse size.

It's quite commonplace for a 16A supply to an airing cupboard to feed both the immersion and a 3A FCU for the central heating.

Your shower pump will quite happily share the little-used immersion circuit with no need for special measures.


Lucia.

 

[currykid]

Thats great.
Thanks Lucia.

 

[kai]

I am surprised that the recommendations were not changed to permit immersions on upstairs ring final circuits, and shared immersion circuits on a 13+3amp = 16amp basis.

Upstairs rings tend to have light loadings anyway, i.e. a few bedside lamps, a couple of TV sets, and a few mobile phone chargers etc.

Immersions nowadays are only acting as backup to a gas central heating system, so tend to be very lightly used these days.