16A Spur for Immersion Heater - Additional Fused Spurs

I am thinking of making use of the 16A tripped supply in my airing cupboard for a shower pump. The only thing is a previous owner of the house has been there before me and taken two fused spurs off the back of the immersion fused outlet supplying the central heating boiler & circulation pump/timer.

Assuming the Immersion heater is 3kw. The Shower Pump is no more than 200w. The Central Heating Pump is say <100 watts. The boiler is say <100w. At 3400W (14A) am I pushing the limit of the 16A breaker in the Consumer Unit?

Each of the spurs of the back of the Immersion outlet will be a switched/fused outlet with the shower pump going through a 30mA RCD switched/fused outlet.

Is what I'm doing considered best practise under the circumstances?

Any advice/opinion would be gratefully received.

Water heating vessels over 15 litres need their own fixed supply. There should be no spurs off a circuit supplying such an appliance.

However, looking at the ratings of the appliances on the spurs, theres nothing technically wrong with it as it is. Just dont make it any worse.

Also, there should be one point of isolation for the whole heating system and all electrically attached components. Why they used two fused spurs is beyond me (I dont think this would work either).

Find another circuit to spur off. You may use the lighting circuit, but you must use an RCD fused spur (unless theres an RCD at source)

Steve said:

Also, there should be one point of isolation for the whole heating system and all electrically attached components. Why they used two fused spurs is beyond me (I dont think this would work either).

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Sounds like an old gravity primary system where the pump (rads) is isolated during the summer months

Steve, Thanks for the reply. I may have been misleading you with my description.

On the immersion fused switch a second fused swith has been added to supply a distribution box that distributes supply to the central heating control box/boiler/pump. Therefore the 2.5mm T&E 16A supply intended only for the immersion heater now branches to two fused switches. What I'd like to do is add a third for the shower pump.

As you point out, what I am concerned about is what you can or cannot do with this circuit "there should be no spurs off a circuit supplying such an appliance"

Using the lighting circuit concerns me as I'd like to avoid dimming lights when the shower pump operates.

Hope this helps describe my plans/question.

Cheers
Graham

Your lights wont dim. This only happens with large loads, and will happen regardless of which circuit its on. And CFLs dont dim when voltage drops. Hurray for CFLs.

[quote="Sounds like an old gravity primary system where the pump (rads) is isolated during the summer months [/quote]

Yes, its an old gravity system, but the central heating system runs in the summer heating the water only.

Sorry if my original description was mis-leading.

Steve said:

Your lights wont dim. This only happens with large loads, and will happen regardless of which circuit its on. And CFLs dont dim when voltage drops. Hurray for CFLs.

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Pleased to hear the lights won't dim - this was my main concern - well that and whether you can wire such an appliance onto a lighting ring.

So, if I break into the lighting ring, conveniently situated in the loft where the pumps going to go, use a switched/fused/rcd outlet, all will be fine as far as good wiring practice?