Electrical (lighting question)

SB118 · 20 Mar 2006 at 18:56

Trigger said:
Yeah, but it will most likley be two core cable- i.e. have no earth which it requires

Shush, you're making me look stupid. And i don't need any help for that

fluiduk · 20 Mar 2006 at 19:11

Now you have lost me.

Surely if the light that the switch and cable is currently on doesnt have an earht, and it doesnt, then why does the new one need one? The back of the fitting isnt open.

The reason I want to use the fitting on the plug is because I am using it as an uplighter not a ceiling light. The light is going to be fixed to a piece of MDF.

What would you recommend?? Other than any major electrical socket moving, as I cant do that

Cheers
Aaron

Trigger · 20 Mar 2006 at 19:20

fluiduk said:
Now you have lost me.

Surely if the light that the switch and cable is currently on doesnt have an earht, and it doesnt, then why does the new one need one? The back of the fitting isnt open.

The reason I want to use the fitting on the plug is because I am using it as an uplighter not a ceiling light. The light is going to be fixed to a piece of MDF.

What would you recommend?? Other than any major electrical socket moving, as I cant do that

Cheers
Aaron

I think you wil find that the fitting has a connection for an earth so you must connect an earth to it. Just do as I said abov and it will work fine- don't omit the RCD though

Adam_151 · 20 Mar 2006 at 19:31

Trigger said:
It must then have an inline switch rated at 13 amps and then have an RCD breaker wired directly on to the end all wired in 1.5mm squared 3 core flex

Why? As long as the design current is lower than the overload protection (the fuse) and that is lower than the current the cable is capable of carrying continously then its ok. The design current of this is going to be less than an amp as the fixure will only be used with 50w or smaller lamps (never seen a GU10 > 50w and even if they did exist, I bet the fitting has a max wattage of 50w per lamp due to heat issues) to install 1.5mm² flex and a 13A BS1362 is completely pointless, 0.75mm² flex on a 3A BS1362 will be fine, though you are right about the earth, and I'd be interested to know why you suggest putting an RCD on it, as long as its constructed properly an RCD is not needed and anyway an RCD is not an excuse for sloppy work

Trigger · 20 Mar 2006 at 19:44

Adam_151 said:
Why? As long as the design current is lower than the overload protection (the fuse) and that is lower than the current the cable is capable of carrying continously then its ok. The design current of this is going to be less than an amp as the fixure will only be used with 50w or smaller lamps (never seen a GU10 > 50w and even if they did exist, I bet the fitting has a max wattage of 50w per lamp due to heat issues) to install 1.5mm² flex and a 13A BS1362 is completely pointless, 0.75mm² flex on a 3A BS1362 will be fine, though you are right about the earth, and I'd be interested to know why you suggest putting an RCD on it, as long as its constructed properly an RCD is not needed and anyway an RCD is not an excuse for sloppy work

Err.. who said anything about sloppy work? All portable light racks like spots and stuff all have RCD's on them to protect them. Secondly, who said anything about 13A fuses? The supply cable should be bigger than the protecting fuse and fuses don't 'burn-out' on overload as well as MCB's and RCD's do and although the RCD doesn't directly stop overload, it will protect it in the sense of an imbalance of current between the live and neutral- i.e. if something is drawing more current than it should

Sorry if my reply is a bit muddled, i'm trying to cook tea at the same time

fluiduk · 20 Mar 2006 at 20:02

God you lot, im confused! Im just gonna throw it in the bin.

The unit does not have a connection for an earth lead? Where does that leave me lol

Aaron

Adam_151 · 20 Mar 2006 at 20:05

Trigger said:
Err.. who said anything about sloppy work? All portable light racks like spots and stuff all have RCD's on them to protect them.

I can't see why its necessary

Secondly, who said anything about 13A fuses?

Sorry I mis-read you post slightly, but the core point is still there, to use 1.5mm² flex would be over engineering it

The supply cable should be bigger than the protecting fuse

Yes, and 0.75mm² flex is perfectly ok for a 3A fuse

and fuses don't 'burn-out' on overload as well as MCB's and RCD's so

Depends on the nature of the fault current, fuses are better at clearing large fault currents because their let through energy is more a less constant, whereas with MCBs the let through rises in proportion with the square of the fault current, for fault currents in the hundreds rather than thousands of amps, yes an MCB will be faster

and although the RCD doesn't directly stop overload, it will protect it in the sense of an imbalance of current between the live and neutral

Why do you need such protection though, RCD protection is generally employed where the Zs are too high for the overcurrent device to protect against indirect contact (such as in a TT system) or where there is a risk of direct contact (such as from cut mower cables)

- i.e. if something is drawing more current than it should Indeed, but where is

No, you got it right above

Adam_151 · 20 Mar 2006 at 20:06

fluiduk said:
The unit does not have a connection for an earth lead? Where does that leave me lol

Sorry, I read it properly this time, look for the double insulated symbol (two concentric squares, if you find it it doesn't need an earth)

fluiduk · 20 Mar 2006 at 20:09

Sorry that was my bad, just taken the cover off and found it.

It has an earth connector

So could I get a lead with an earth wire and do it that way. If needs be I can do away with the switch and plug it into an extension lead in a more accessible place.

Aaron

Trigger · 20 Mar 2006 at 20:15

fluiduk said:
Sorry that was my bad, just taken the cover off and found it.

It has an earth connector

Well you want a 3 core cable, anything above 0.75mm will do (Although I would stil say at least 1.0mm) with a 13A inline switch and a 3A fuse. I would still put an RCD on the end though just for added protection and they don't exactly cost the earth now do they as they used to cost £100 upwards

fluiduk · 20 Mar 2006 at 20:16

Cool, thanks. I will goto the well known, but rubbish electricals store tommorrow and see what they have. thanks for the help.

Ps is it ok to wire it up with the lead i have now just to check it works before I goto the hassle of spending all my money lol? Or will i blow up?

Thanks

Trigger · 20 Mar 2006 at 20:20

fluiduk said:
Cool, thanks. I will goto the well known, but rubbish electricals store tommorrow and see what they have. thanks for the help.

Ps is it ok to wire it up with the lead i have now just to check it works before I goto the hassle of spending all my money lol? Or will i blow up?

Thanks

You would probably get away with it but I wouldn't advise it due to the lack of an earth

fluiduk · 20 Mar 2006 at 20:23

I will leave it then. Dont want to die.

Ps... will this do the job

'To BS6500 1990 Table 16
A 3-core mains cable with a thick outer sheath available also in orange for added safety when used as a trailing lead, e.g. on power tools. Stranded core, three 40/0.2mm copper conductors with brown, blue and green/yellow PVC sheaths in an overall round PVC sheath.'

I dont get what it means with the widths there. 40/0.2mm ???

Thanks for all the help and sorry to be a pain

Aaron

wandgrudd · 20 Mar 2006 at 20:29

Trigger said:
Well you want a 3 core cable, anything above 0.75mm will do (Although I would stil say at least 1.0mm) with a 13A inline switch and a 3A fuse. I would still put an RCD on the end though just for added protection and they don't exactly cost the earth now do they as they used to cost £100 upwards

Why do you need a RCD on a light? If anything putting an RCD on a light is daft as it could trip if the bulb pops. This being the reason you have split load consumer units where only one side is connected to the RCD (i.e. the rings/cooker etc) so that if some thing does go wrong you aren’t left with out lights

Trigger · 20 Mar 2006 at 20:43

What's your problem? It costs a few pounds and gives added protection to a portable device, why not :confused:

fluiduk · 20 Mar 2006 at 20:45

Ladies! lol

For the record I will be putting an RCD on it, as I have one spare lol.

What does 40/0.2mm mean with regard to the thickness of the cable?

Aaron

wandgrudd · 20 Mar 2006 at 20:49

Trigger said:
What's your problem? It costs a few pounds and gives added protection to a portable device, why not

What’s my problem? Well I can’t see any reason why he needs to add an RCD to a light. Why spend money on some thing that’s not needed. (cant see where it says its going to be portable)

:confused:

wandgrudd · 20 Mar 2006 at 20:52

fluiduk said:
Ladies! lol

For the record I will be putting an RCD on it, as I have one spare lol.

What does 40/0.2mm mean with regard to the thickness of the cable?

Aaron

I would think it means 3 cables made up of 40 x 0.2 strands of wire. Sounds a bit thick for what you want.

looking at a shop with map in its name?

Trigger · 20 Mar 2006 at 21:21

wandgrudd said:
What’s my problem? Well I can’t see any reason why he needs to add an RCD to a light. Why spend money on some thing that’s not needed. (cant see where it says its going to be portable)

Well from how I was reading it, I understood it was going to be portable. Maybe just me? Sorry

Would probably be better looking at Screwfix IMO

fluiduk · 20 Mar 2006 at 21:34

Yeah looking at m, theres a branch next to my building lol

They have a 24/0.2mm but thats 6amp? That be ok?

Thanks