Pond pump lighting circuit

[Elecgb]

Hello,

I would like to connect the outdoor pond pump onto the lighting circuit via a rcd.

Pump uses no more than 30w so intend to use a 1 amp fuse. Is it o.k to do this. Was thinking of using this rcd which looks like it comes with 13amp fuse which i will replace with the 1 amp fuse.

http://www.screwfix.com/p/volex-13a-rcd-fcu/83049

Would this rcd be o.k

Comment welcome.

 

[bernardgreen]

It is not a good idea to connect a pond pump to a lighting circuit. Being outside and "wet" the chances of a fault are high. You do not want to lose your lights when the pond pump decides to go faulty.

Losing power to a few sockets is bad but being in the dark is worse when trying to find the fault.

 

[Elecgb]

I thought the 1amp fuse would blow before the 6amp rcd for the lights

 

[Mrdjc]

RCD and fuse ratings are different

 

[mikeyd]

What is the reason behind connecting it to your lighting circuit? Easy access to that circuit or something else?

You haven't got a 6 Amp RCD on your light circuit. You might have a 6A RCBO, or more likely a 6A MCB (which may, or may not be protected by an RCD further upstream). But what you do have will determine if the fused RCD outlet is needed.
Having said that, pond pumps don't really have a place on an internal light circuit.

 

[Elecgb]

Sorry, ment to say 6amp mcb on lighting circuit.

Just thought that better to have electric supplied via lighting circuit rather than a long extention lead plugging the pump into the mains supply from a kitchen socket which looks an eye sore. The pump will have it's own rcd supplied via lighting circuit so I think this would trigger before the 6amp lighting mcb.

Would this be o.k

 

[Aragorn84]

If the lighting circuit is also protected by an RCD, you may well find that should a fault occur, both devices would trip anyway, plunging your house into darkness, which is clearly unsafe.

Surely its just as easy to take a feed from a more suitable circuit, than to be hacking around in a roof space to tap into the lighting feed?

 

[ericmark]

The RCD FCU you have selected is OK but I would consider using a 10ma for a pond although they are expensive.

To run pond lights and pump off the same supply I don't see as a problem but one would not run it from house lighting supply.

The problem with domestic outdoor is the Part P requirements.
You have two options.
1) Use a scheme registered electrician.

2) Go through the steps required to DIY which are:-
a) Design the system and submit the design to the LABC. (Paying fee)
b) Install the system
c) Test and inspect the system filling in the minor works or installation certificate as you go.
d) Submit the certificates to the LABC who may want to re-test parts to confirm readings submitted.
e) Get the completion certificate from the LABC.

To use second option will require you to buy or hire test equipment likely costing £75 just to hire. Also you may need to prove to the LABC you are competent which could mean they will ask to see a C&G2392 or similar qualification.

Although in theroy you can DIY in practice it is only to allow an electrician who is not a member of a scheme to do the work and where unqualified people try to use the system often the charges to get the work inspected and tested plus the LABC fees mean it's far more expensive than just getting an electrician to do the work for you.

As to fuse v MCB the time taken to open a MCB is very different to that taken to blow a fuse and so it is common that a B32 MCB will open with a short circuit before or as well as a 13A fuse blowing where the loop impedance is below 1.44 ohms.

314.1 Every installation shall be divided into circuits, as necessary, to:
(i) avoid hazards and minimize inconvenience in the event of a fault
(ii) facilitate safe inspection, testing and maintenance (see also Section 537)
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation
(v) mitigate the effects of electromagnetic interferences (EMI)
(vi) prevent the indirect energizing of a circuit intended to be isolated.

Would clearly not be complied with if you power non lighting circuits from the lighting supply.

 

[Elecgb]

Thanks for the replies.

Can I do all the electrical work and have a qualified electrician come and check the wiring and connect the circuit to live. It seems from what I have read that this is not allowed. Correct me if wrong.

 

[flameport]

Can I do all the electrical work and have a qualified electrician come and check the wiring and connect the circuit to live

No, you can't.

Work such as this is notifiable, which means either you notify and do the work yourself, or the electrician does the work and then notifies. There is no way for an electrician to notify work which you have done.

Even if is wasn't notifiable work, expecting an electrician to arrive and connect up some unknown wiring simply won't happen, as it would have to be inspected and tested first. Inspecting being rather difficult where cables have been concealed in walls, floors, buried in the garden etc.

There is also the very real possibility of the electrician not liking what you have installed, resulting in you paying someone to tell you that what you have installed is unsuitable / incorrect / unsafe / all of those.

On larger projects, it is often possible to arrange with an electrician for you to do some of the work, such as digging a trench down the garden. However you would have to agree everything with the electrician before anything was done.
For a small job of connecting a pump, that approach won't be worthwhile for anyone.

 

[Elecgb]

That answers my questions. Thanks for the replies.