Shower pump and extractor fan in loft space

[mike42]

Hi All

pump is 40w and fan is 24w. Fan switches on with lights (4 spots) and off after a time. I plan to take a feed from existing 5a lighting circuit that isn't heavily loaded.

Pump manufacturer instructions say it needs to be on a fused spur. Fan says it needs to be behind a triple switch.

My question is, is there a standard/normal way to wire this (and which is it?) ? I mean I think I can see one or two ways of wiring this so it complies: e.g.:

1/ Put everything including lights behind a double pole fcu . Then no fan switch required.
2/ Do them as two seperate spurs with both triple isolator for fan and single pole fcu for pump.

Are either of those two the "right" way to do it or is there a more "normal" way?

 

[EFLImpudence]

There is no electrical reason for either a further fuse, in addition to the circuit 5A, nor a switch.

Therefore you can fit them wherever you want if you choose to follow the instructions.

 

[winston1]

There is no electrical reason for either a further fuse, in addition to the circuit 5A, nor a switch.

Therefore you can fit them wherever you want if you choose to follow the instructions.

Which you don't have to. The instructions are for guidance only.

 

[flameport]

Either option could be done.
It is desirable to have an isolation switch for the fan and pump for the inevitable day when one or both fail.
The fan will need to be 3 pole (line, switched line, neutral). 2 pole for the pump.
Extra fuses not required.

 

[333rocky333]

Which you don't have to. The instructions are for guidance only.

says who

 

[EFLImpudence]

says who

Anyone who can tell that they are unnecessary -

and 7671 now which says they merely should be taken into account.

 

[333rocky333]

Anyone who can tell that they are unnecessary -

and 7671 now which says they merely should be taken into account.

18th yes, which comes in force january, I dont have the latest 17th but i do believe the original 17th said they "Shall" be followed.
Though i admit there not always right.

 

[DetlefSchmitz]

Actually 'manufacturer's instructions' appears dozens of times and is followed by 'shall be followed', 'should be taken into account' or other, depending on the context. It is not a clear cut question.

 

[EFLImpudence]

18th yes, which comes in force january, I dont have the latest 17th but i do believe the original 17th said they "Shall" be followed.

510.3 17th

 

[333rocky333]

510.3 17th

Maybe you meant 510.2
That refers to "Equipment" not necessarily "Electrical equipment" as does 134.1.1

The early 17th 134.1.1 said,
"Electrical equipment shall be installed in accordance with the instructions provided by the manufacturer of the equipment"

This is now in the 18th 134.1.1 as,
The installation of electrical equipment shall take account of manufacturers' instructions.

I am sure Winston 1 will clear this up

 

[mike42]

Thanks for the answers and interesting follow up discussion on the regs.

I'm now minded to do away with the extra fuse and have both fan and pump protected by a single triple pole switch.

Still a little tiny bit of a niggle with the pump instructions saying it should be protected by a 3amp fuse(d spur) and the fact that the existing circuit has a higher rated 5a mcb (soon to be replaced with a 6a rcbo).

 

[333rocky333]

The difference between 3 and 5 is negligible, the instructions are more aimed at preventing people putting it on Higher rated circuits like 15, 20 amp etc, the isolation part of the instructions is to me more important. Most stipulate Double pole at least which is generally achieved by fitting Switched FCU'S or Fan isolaters.

 

[winston1]

Thanks for the answers and interesting follow up discussion on the regs.


Still a little tiny bit of a niggle with the pump instructions saying it should be protected by a 3amp fuse(d spur) and the fact that the existing circuit has a higher rated 5a mcb (soon to be replaced with a 6a rcbo).

The fuse is not to protect the fan which should be internally protected. It is to protect the cable w hitch is well over 5 a.

 

[333rocky333]

If the pumps in the loft put the switched fcu next to it in the loft with a 3 amp fuse in, if it bothers you, plus its there to isolate if you need to work on it

 

[mike42]

After your helpful comments it doesn't bother me any more! Thanks so much.