immersion heater wall switch

anna42hmr

I am arranging for the electric switches /sockets in my property to be changed, however looking at the range i am going for, i am trying to establish what ones i need to order for my immersion heater. (they will be fitted by a friend of family who is an electrician but i am ordering the switches, spurs etc ready for him to fit). Unfortunately he is away for a few weeks on holiday so can't contact him until he comes to fit them, the current wall switch is switch with a neon and a built in fuse.

The range that i am intending to order from does several versions, one with a neon and fused (13amp) and also does two other options, 20A double pole switches (non fused) and 45A Double pole switches.

As the existing one is fused does it mean therefore i would need to order the fused one or would i be able to use one of the other two either?

southcoastrgi

Immersion heater shouldn't be connected to a fused spur, however it should be on its own circuit back to the consumer unit

Myser

Is the immersion heater only for occasional use?

Is so, consider an automatic immersion heater boost timer switch as it is easy to leave the switch on and rack up a bill.

Something like these:

http://www.screwfix.com/p/horstmann-e30-boost-timeswitch/93158

http://www.timeguard.com/products/time/immersion-and-general-purpose-timeswitches/tgbt4-electronic-boost-timer

If you just want a standard immersion heater switch, then go for something like this with a neon:

http://www.screwfix.com/p/crabtree-20a-1g-immersion-heater-switch-neon-white/4343j

As southcoastrgi said, the immersion heater should be on its own circuit and not a spur.

Ectophile

Immersion heaters are often connected to 13A fused connection units (FCUs). Unfortunately, these frequently overheat, especially if they are inside the airing cupboard.

If the immersion heater is on its own circuit, with an appropriate fuse/breaker at the consumer unit, then there's really no need for the extra 13A fuse anyway.

A 20A double pole switch should work fine. A 45A one is a bit of an overkill.

Heedtheadvice

I agree with Ecto....
Not only will 20A double pole switch be adequate (allow at least 4A per kW) the 40A may well have connections terminal size s too big for the cable in use.
A neon indicator is preferred as (as has been posted) all too easy to leave switched on and even with a thermostat can run away with costs especially if lagging is poor. The timers are a good idea (not my preference though) but rarely fitted and may not match your socket/switch choice of style.

I would add it is worth going for a good make rather than a budget range of sockets/switches as they are far better usually and are not as prone to breaking upon installation so may well not cost much more in the long run.

anna42hmr

Thank you everyone for the replies and suggestions, I will look into them further.

The switch range is made by deta and from info have found they seem to me a good manufaturer

brightontraveller

Is there any particular reason your just replacing sockets , switches etc not cable , Cu etc if its “gold plating” the installation to be honest its complete waist of time, If not then best let you electrician purchase the materials they will know the correct ones to buy if they will take load, fit in back boxes, correct for location etc

southcoastrgi

Ectophile wrote: »

Immersion heaters are often connected to 13A fused connection units (FCUs). Unfortunately, these frequently overheat, especially if they are inside the airing cupboard.

Yes they are & that's not correct, the household supply is normally between 230v-240v & most immersion heaters are rated at 3kw therefore at 230v the amperage is 13.05 & over the highest fuse rating for a normal fused spur

Risteard

southcoastrgi wrote: »

the household supply is normally between 230v-240v

The nominal supply is U of 400V and Uo of 230V AC rms +10%/-6%

tonyh66

Risteard wrote: »

The nominal supply is U of 400V and Uo of 230V AC rms +10%/-6%

well that makes sense then. I hope my supply never reaches 400V, keep it simple, its not an electrical engineering forum. What Southcoastrgi said was not wrong.

Risteard

tonyh66 wrote: »

What Southcoastrgi said was not wrong.

Actually it was. The supply frequently exceeds 240V and frequently dips below 230V. The single phase supply can legitimately vary between 216.2V and 253V.