Immersion Heater Electric Circuit

[jaydebruyne]

My boss has sent me on a job today to fit a fused spur for an immersion.

I said it needs its own circuit.

He said no it doesn't as its only 3Kw.

Is this true?

I'm sure the regs are that if a water heater is in a tank of more than 15 litres it needs a separate circuit.

 

[quality]

Its nothing to do with the amount of water its the wattage rating of the fixed equipment. Without repeating the regs it does need its own circuit. If your fitting new instalations you should know this

 

[jaydebruyne]

Its nothing to do with the amount of water its the wattage rating of the fixed equipment. Without repeating the regs it does need its own circuit. If your fitting new instalations you should know this

The building regs states capacity with regards to electrical requirements. And I do know but I just wanted to confirm as he made me question. But thanks anyway

 

[quality]

What regs refer to quantity of water regarding an electrical circuit, I may be missing something

 

[jaydebruyne]

What regs refer to quantity of water regarding an electrical circuit, I may be missing something

The IET on-site guide... Page 177:

"Water heaters fitted to storage vessels in excess of 15 litres capacity should be supplied by their own separate circuit."

 

[stevetheplumber]

obviously allows smalll point of use to be on the ring which makes sense

 

[plumben]

Is/was this job to just rewire a new fused spur outlet onto existing wires and new flex to immersion or wire in a new fuse spur off the back of a socket?

 

[jaydebruyne]

Is/was this job to just rewire a new fused spur outlet onto existing wires and new flex to immersion or wire in a new fuse spur off the back of a socket?

The immersion was wired into a fused switch which also fed the boiler so you couldn't isolate them independently. The job was to run a switched fused spur from this switch to feed the immersion.

 

[cr0ft]

It's fairly common to use a dedicated immersion heater circuit to power a pump in an airing cupboard or something similar such as a boiler. 2.5mm cable should cope with both loads nicely depending on how it's been run.

Running immersion heaters and other permanently connected appliances from a ring mains is bad practise but what you are suggesting sounds fine if the existing fused spur is on a dedicated radial circuit wired in 2.5mm twin and earth.

If it's on a ring mains I wouldn't do it at all, especially with a boiler already permanently connected too.