Discuss SELV garden spike lights in the Lighting Forum area at ElectriciansForums.net

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Steve T

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Hi,
Years ago we had a sparky install some 240v garden lighting but to one of the points in the garden that we wanted lighting in he only installed a buried SWA cable and terminated it in a jb because at the time we needed some other work doing in that area before lighting could go in. Anyway we've finally got round to wanting to install lighting, and my plan is to use spike lights. The area they are going in is a flowerbed so some digging could feasibly happen in the future. So I thought it would be best to use SELV spike lights, but I couldn't really find any (other than amazon specials) with a gu5.3 base so I was thinking of buying normal gu10 ones from the likes of screwfix and using a gu10 to gu5.3 adapter and running them at 12v. I'd rather not use any integrated led ones as I've heard they are very susceptible to failure and filling up with water, so would rather use ones that where I can just replace the lamp if it goes. Also the top of the range stuff (collingwood etc) is a bit expensive for me for the specs I want. Hope that sounds sensible.
So my questions are;

1) What is the best way to protect the cable from the lights from damage? At most the cable would have to run about 1m in the flowerbed before it gets to a fence it could be clipped along. I'm thinking I could use kopex as some protection and then bury it as deep as the SWA (50cm)? It could of course just go on the surface so anyone digging would see it but that would look unsightly. Are there any better ways of protecting it?

2) This is probably a silly question but am I right in thinking that if I go down the route of converting 240v gu10 lights to selv lights I should NOT connect the cpc?

Thanks for any replies!
 
Answer to question 2 first. Don’t convert the lights. They are designed For the voltage they are intended.

what is the reason you want selv. Nothing wrong with 240/230V in garden. I am presuming the garden is RCD protected.

answer to first question is if it’s RCD protected then just run surface , maybe cover cable with flex conduit to give a little light mechanical protection. You can get flex cond in black, green, white.
 
You can get flex cond in black, green, white.

is that striped, or random?
 
Answer to question 2 first. Don’t convert the lights. They are designed For the voltage they are intended.

what is the reason you want selv. Nothing wrong with 240/230V in garden. I am presuming the garden is RCD protected.

answer to first question is if it’s RCD protected then just run surface , maybe cover cable with flex conduit to give a little light mechanical protection. You can get flex cond in black, green, white.
I actually got the idea of converting 240v lights to selv lights from one of David savery's videos. Reason I wanted to go for selv is because I can't see how I can adequately protect a 240v flex in a place where damage is possible. At least with selv if any damage occurs it won't be dangerous and won't trip anything, the lights and perhaps driver will just stop working. It is all rcd protected.
 
If it’s rcd protected then no selv necessary. I’d never put outside power on the same rcd as any household protected rcd. Separate RCD every time.

id be interested to see that video.
 
If it’s rcd protected then no selv necessary. I’d never put outside power on the same rcd as any household protected rcd. Separate RCD every time.

id be interested to see that video.
This is the videos I was referring to:


Unfortunately I've got a wylex 16th edition split board and all the outdoor lighting is taken from a spur off the downstairs ring final circuit. I know it's less than ideal and would much rather it was on a separate rcbo but my sparky said it was not possible to fit a new wylex rcbo into my board as it has a fixed busbar so the new and old devices are incompatible.
 
I don't think that this is necessarily such a bad idea. 230V garden lighting is notorious for developing faults, and it's not always possible to have a dedicated RCBO for the circuit.

There are a couple of other things you need to consider though. At 12V, the current will be much higher than at 230V. Can the fittings take the higher load? Also, will permitted voltage drop be exceeded?
 
Have you got an idea of the number of lights, power for each, and the sort of distances involved?

12V SELV is a good idea but the voltage drop is 20 times more serious than at 240V!
 
I will be using 2 or 3 spike lights, with probably 350lm gu5.3 led lamps which are around 5.5w each but depending on what it looks like I may go for brighter lamps at around 8.5w each. The maximum distance of cable that seems to be supplied with these spike lights is 5m but I can't find any cable sizes. I would have thought it would not be less than 0.75mm2. If I place an adaptable box for the driver strategically there would only need to be a maximum of around 2m of cable from the fitting to the driver so the voltage drop would not be an issue over this sort of length according to a online volt drop calculator. If I convert a gu10 fitting to selv the fittings are rated for 50w gu10 lamps but I think that's more to do with the heat produced from a lamp? So for a 50w gu10 at 240v the current is 0.2A but for a 8.5w 12v lamp the current is 0.7A. Does anyone happen to know what the current rating for a gu10 holder is? Or even better are there any decent gu5.3 spike lights? I could only find stuff on amazon which is of potentially dubious quality.
 
Use Collingwood spike lights.

The best imo and SELV so no RCD tripping to worry about. You’ll pay a bit more though.
 
Use Collingwood spike lights.

The best imo and SELV so no RCD tripping to worry about. You’ll pay a bit more though.
Thanks, I was aware of the collingwood range but as you say the price is certainly up there. Also, call me old fashioned but I don't personally like integrated led units, had too many (fairly expensive) ones fail,
 
These holders are 2A rated:

Subject to max temperature limit, of course!

Generally if you are looking for outdoor rated cable like SWA / tuff sheath / H07RN-F the smallest you usually get is 1.5mm which is about 25 mOhm/m for DC. If you are looking at 3 * 0.7A = 2.1A then 19m until you reach 1V drop.

The "tuff sheath" from Doncaster Cables is easier to use than NYY-J as it is stranded cores, otherwise both are like SWA but without the steel armour and pretty tough. At mains voltages they should not be buried directly in the ground in the UK as our wiring regs require SWA for that role (with its earthed armour) or the use of suitable cable duct for added protection.

H07RN-F is flexible rubber, quite hardy but not suitable for burial in the ground. With some duct or similar it would be a good choice as easy to work with.

These sort of cables can usually be bought by the meter from electrical wholesale outlets or from various web sites like Superlec Direct, CEF, etc.
 
Thanks, I was aware of the collingwood range but as you say the price is certainly up there. Also, call me old fashioned but I don't personally like integrated led units, had too many (fairly expensive) ones fail,

I’ve just looked through my records and I’ve fitted around 200 over the past 6 years and no failures. I’ve had to replace 3 drivers in that time. You get a 7 year extended warranty too. Well worth 50 or 60 quid a pop imo.
 
These holders are 2A rated:

Subject to max temperature limit, of course!

Generally if you are looking for outdoor rated cable like SWA / tuff sheath / H07RN-F the smallest you usually get is 1.5mm which is about 25 mOhm/m for DC. If you are looking at 3 * 0.7A = 2.1A then 19m until you reach 1V drop.

The "tuff sheath" from Doncaster Cables is easier to use than NYY-J as it is stranded cores, otherwise both are like SWA but without the steel armour and pretty tough. At mains voltages they should not be buried directly in the ground in the UK as our wiring regs require SWA for that role (with its earthed armour) or the use of suitable cable duct for added protection.

H07RN-F is flexible rubber, quite hardy but not suitable for burial in the ground. With some duct or similar it would be a good choice as easy to work with.

These sort of cables can usually be bought by the meter from electrical wholesale outlets or from various web sites like Superlec Direct, CEF, etc.
Thanks for the info, I've just looked at an existing 240v spike lights we have in our garden put in by a sparky some years ago and it seems to come pre flexed with 0.75mm2 H05RN-F, he decided to use 240v as the light was positioned right next to a post so the cable does not need to run on the ground at all. All cable run underground is 1.5mm2 SWA. Presumably any new lights would also come with H05RN-F. So is H05RN-F also suitable for outdoor use? Surely it must be or why would they supply it with that cable?
 
So is H05RN-F also suitable for outdoor use? Surely it must be or why would they supply it with that cable?
Yes, the '07' and '05' parts of the harmonized code is the voltage limit, but both are fine for the 230V supply range.

You can get less than 1.5mm in most cable types but as that is the smallest for "fixed power wiring" in the UK regs (1mm for lights) it is harder to find it stocked.
 
I’ve just looked through my records and I’ve fitted around 200 over the past 6 years and no failures. I’ve had to replace 3 drivers in that time. You get a 7 year extended warranty too. Well worth 50 or 60 quid a pop imo.
Fair enough, I'll take a look at them. Wasn't aware of the 7 year warranty!
 
Have a look online, but you can get GU10s and even E27 and B22 in low voltage, I have used them in the past for outside lights and on canal boats.

Most are sold in 12v or 24v, if you go with 24v the current will be slightly less
 
Have a look online, but you can get GU10s and even E27 and B22 in low voltage, I have used them in the past for outside lights and on canal boats.

Most are sold in 12v or 24v, if you go with 24v the current will be slightly less
Good shout, I'll check that out as well. I've seen stuff like that of questionable quality on ebay in the past but if I can find something from a reputable supplier that might be a good option.
 

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