Spur off a spur for a shower pump?

[stevejoyce]

Is it possible to spur off a spur to install a shower pump (3amp)

What I mean exactly is: the wiring centre for my Central Heating controls are in my bathroom, in the airing cupboard. Is it possible, to take a spur off the L, N and Earth from it, into a fused connection unit which I could put right next to/above it, and then run the shower pump from this?

I did believe you could not spur off of a spur, but have read and heard that you can AS LONG as you fuse it? so could i fuse it at 3 amps, and replace the current 3 amp fuse for the wiring centre with a 6 amp fuse??

any advice would be great...

 

[Spark123]

No, you should not increase the size of the fuse in the existing fused spur for the central heating as that has been sized to accomodate the wiring in the central heating. You can place a 13A fused spur before the central heating fused spur and run another fused spur from it.
Is the shower pump going to be in the bathroom? Is it on an RCD protected circuit?

 

[stevejoyce]

pump would be in bathroom - next to hot water cylinder, so close to spur.

hmm, not sure, didn't think about a RCD.

do you mean take a spur off the wiring centre and rate it at 13amp? why 13amp though, the shower pump only requires 3amp?

 

[Spark123]

Nope, I mean have the cable from the supply to a 13A Fused spur unit and use that to feed a 3A fused spur for the boiler and a 3A fused spur for the pump, so you have 3 fused spur units in total.
If the pump is going to be in the bathroom then it will probably be notifiable under part P too

[code:1]
Supply---------[13A]------------[3A]---------Central Heating
|
|
|
[3A]
|
|
Pump
[/code:1]

 

[stevejoyce]

so i wouldn't need to do anything to the conumser unit, except for isloating the power to the spur (s) whilst altering them.

i'll have to think about this and the best way to do it.

notifieable? do you mean i'd ned to write to them before i start the work?

one last question: why a 13amp fuse, why not 6 amp (as: 2 x 3amp)?

 

[GaryMo]

Because you can't get a 6A BS1362 cartridge fuse.
There's nothing at all wrong with a 13A FCU supplying 2 x 3A FCU as posted above.

There's a little more to it that writing to building control. There's also the small matter of how much it will cost you - in the region of £200 for your trouble!
You need to speak to your local LABC as they're all different for some reason

However, there's a good chance that the internal area of your airing cupboard doesn't fall within the zones set out by BS7671:2001 so there may be no need for notification.

 

[stevejoyce]

LABC ? : local authority building control??

sound like it couls be a long process......

 

[Spark123]

If it is notifiable then either you need to notify your local authority building control and pay their fee before you start or have a sparky do the work for you who is a member of a competent person scheme and can notify the LABC themselves via their scheme. For a small job like this the sparky route will probably be cheaper.

I said 13A as that is a common size, it is there mainly to protect the cable supplying it from being overloaded should someone decide to install a heater from each of the downstream fused spurs in the future.
Instead of a spur from a spur you will have a radial circuit with two fused spurs on if you see what I mean.
Also, I can't think I have ever seen a 6A plugtop fuse, 3A, 5A and 13A are the most common but there are some more less common sizes.

 

[GaryMo]

LABC ? : local authority building control??

sound like it couls be a long process......

Yep.

 

[stevejoyce]

thanks for you help everybody.

i suppose a sparky can self certificate/sign-off the work without the need to contact the LABC and therefore no waiting around time.

will have to think about this now tonight.