Replacing plastic outside light with Metal type

[MarkButNoSpark]

Hi I was looking to change a broken outside light which is of plastic construction with a new Stainless Steel one, my house is only 5 years old so all the wiring is new.

But the instructions on the new light state, and I quote;- Do not wire this lantern into the lighting circuit - use a switched fuse spur.

The current light is just on the outside wall a very a walls thickness away and is fully earthed as is the internal switch which is used to isolate it, but it runs off the lighting circuit.

Do I just have to change the internal wall switch to a fused switch or is it more complicated that this.

 

[ban-all-sheds]

What sort of light? What wattage?

 

[bernardgreen]

Since outdoor lamps can develop earth leakage if ( when ) rain water or hose water gets into the lamp it is advisable to have double pole ( Live and Neutral ) switches to fully isolate the lamp. This prevents the RCD for the circuit tripping on the earth leakage in the lamp. Leakage Neutral to Earth will trip an RCD.

Loss of power ( RCD tripped by lamp ) is less hazardous than loss of the lighting in the house.

 

[MarkButNoSpark]

It has PIR and Max watt is 35amp.

But sounds as though I would need to run a spur from a socket rather than the existing lighting circuit, unless you can put an RCD off the lighting circuit in place/along side of the isolation switch, but never seen anything like this before, well not with a built in switch.

So is it possible to add one between the switch and the light. ???

 

[EFLImpudence]

There is no reason to state a lamp cannot be run off the lighting circuit unless it would use more than the 6A which lighting circuits usually are.
35 Watts is 0.15 Amps (one seventh of an Amp).

So just replace the existing light.

Your modern house will likely have an RCD on all circuits but -
because people have explained the benefit of and reason for a DP switch where earth leakage is likely to affect an RCD does not mean that you would have to fit an RCD if there isn't one.

May change soon with new unnecessary just for the sake of it regulations.

 

[MarkButNoSpark]

I knew my consumer unit had an rcd, but checking again, paying more attention, it has two, if the electrician had lab led them both up I would have a better idea which circuits they cover.

I will test them out on Saturday, so thank you guys, and EFLImpudence for making me check again...

 

[winston1]

Hi I was looking to change a broken outside light which is of plastic construction with a new Stainless Steel one, my house is only 5 years old so all the wiring is new.

But the instructions on the new light state, and I quote;- Do not wire this lantern into the lighting circuit - use a switched fuse spur.

The current light is just on the outside wall a very a walls thickness away and is fully earthed as is the internal switch which is used to isolate it, but it runs off the lighting circuit.

Do I just have to change the internal wall switch to a fused switch or is it more complicated that this.

A typical example of manufacturers instructions being wrong. There is no requirement to follow manufacturers instructions particularly if they are wrong.

 

[sparkwright]

A light that can't be installed on a lighting circuit.

Whatever next?

Have you got the make and model of this light out of interest?

 

[eveares]

You could also replace the light switch for a double pole switch (20A isolator) if the neutral to the light is also at the switch.

 

[MarkButNoSpark]

The light is a Biard Le Mans Round IP44 Double Up Down Outdoor Wall Light with with PIR Motion Sensor - Black Finish - GU10 Garden Lamp Waterproof Lamp, CE, RoHS & LVD certified.

I had a quick look at the switch connections the other day and three cables terminate in there so 3xN, 3xL, 3xE, so will look at a double pole switch.

 

[DaveHerns]

Can't you change the internal switch to a fused FCU with RCD built in? You may need a deeper back box. I've had a 150watt PIR security light running off my garage lighting circuit for 20 years and it's never tripped the RCD so it's up to you really.

 

[ban-all-sheds]

But the instructions on the new light state, and I quote;- Do not wire this lantern into the lighting circuit - use a switched fuse spur.

If you can easily find an email address, drop them a line and ask them to explain why they say that, and let us know.

 

[ban-all-sheds]

In the days of 500W halogen floods, when a couple of those could swallow up most of a lighting circuit's capacity, or just one could push one over the edge if it was already supplying a lot of indoor incandescent lights, it made sense to advise using a socket circuit.

But not nowadays with CFL or LED lights orders of magnitude less.

 

[MarkButNoSpark]

Can't you change the internal switch to a fused FCU with RCD built in? You may need a deeper back box. I've had a 150watt PIR security light running off my garage lighting circuit for 20 years and it's never tripped the RCD so it's up to you really.

Yes I had considered this, not an attractive piece of kit but an option, if I can get a deeper box in, did you also keep an isolation switch in place as seems normal for outside lights or did you use a Fused RCD.

 

[winston1]

Can't you change the internal switch to a fused FCU with RCD built in? You may need a deeper back box. I've had a 150watt PIR security light running off my garage lighting circuit for 20 years and it's never tripped the RCD so it's up to you really.

The circuit is already RCD protected, there is no point in another.
FCUs are not used or required on lighting circuits which are protected by a 6amp MCB. A 3amp cartridge fuse will have no discrimination against a 6 amp MCB.

Just replace the outside light with the new and make sure all the waterproofing is sound. You could change the switch to a double pole type but really not necessary if the waterproofing is sound.