Downlighters Earth Question

[chrisgc]

Just want to get this right before pushing the downlighters into the ceiling.

Using twin and earth, the 12 x downlighters only need AND can only accomodate the line and neutral connected so with regards to the earthing conductor in the twin and earth do I simply crimp and connect the earth too the next light in series until I reach the last light and again terminate the last light in the series with a crimp again to enable continuity of the earthing conductor?

All answers greatly appreciated.

PS The downlighters are mains ones and the small connecting box which goes into the void is reletively small so as I beleive the connector terminals will have the line and neutral looped with next light then the earth will then stay outside the connector box and be crimped together with the next earth in the loop.

Sorry if sounds a little confusing.

 

[BillyBoBob]

Dude never leave cables outside of an enclosure. All conductors must be properly terminated.
Use either a 5A round junction box, (which I prefer) or these which seem to be standard nowadays.
http://www.garagedoorwarehouse.com/__myAssets/electrical_essentials%5Cchoc_box_connector_covers%5CCPE8718%20Chocbox%20in%20situ.jpg

You can connect both your loop in and loop out of your T/E on one side and connect a flex to the other. Note: use heat resistant flex from the Choc box to the fitting. Never connect the T/E to the downlight, it's not designed to take the heat.
Unless your using Fire rated IP65 type http://reguluxgb.co.uk/wp-content/themes/bizat-regulux/images/fire-rated-downlight.jpg then the connection is usually away from the heat source but I'd still apply the method above.

 

[chrisgc]

Dude never leave cables outside of an enclosure. All conductors must be properly terminated.
Use either a 5A round junction box, (which I prefer) or these which seem to be standard nowadays.
http://www.garagedoorwarehouse.com/..._connector_covers\CPE8718 Chocbox in situ.jpg

You can connect both your loop in and loop out of your T/E on one side and connect a flex to the other. Note: use heat resistant flex from the Choc box to the fitting. Never connect the T/E to the downlight, it's not designed to take the heat.
Unless your using Fire rated IP65 type http://reguluxgb.co.uk/wp-content/themes/bizat-regulux/images/fire-rated-downlight.jpg then the connection is usually away from the heat source but I'd still apply the method above.

Thanks for the reply,

So let me get this right first time then - here goes:

1- Twin and Earth (using 1.5mm) to junction box (so looped) that way all terminated correctly and earth safely tucked away.
THEN
2- Connect 2-core (as earth not needed in light connector box) flexible heat resistant cable (unless downlight is fire rated IP65) from junction box to downlight connector.

If thats correct will it be ok to use the following 2 core cable (bearing in mind existing cable is 1.5mm) and there are 12 downlights and I have had to upgrade the mcb on the cb to an increased amp:

0.75mm 2 Core PVC Heat Resistant Flex - 3092Y

I look forward to your reply.

 

[BillyBoBob]

Yep your good to go.
So many lights are installed in this way. I know may people like the choc boxes but I hate e'm.
I'd prefer to use http://www.maplin.co.uk/images/full/vq63t.jpg
They cost more but I think a better job.

Just so I know. Each light will be fed via 1 flex. you will need 12 JB's and 12 Flex'.
loop the Switchline and neutral in T/E from light to light or JB to JB then flex out to each downlighter.
Don't wire all the lights in a single flex from one single JB. hope I didn't misunderstand.

 

[flukey]

Yep your good to go.
So many lights are installed in this way. I know may people like the choc boxes but I hate e'm.
I'd prefer to use http://www.maplin.co.uk/images/full/vq63t.jpg
They cost more but I think a better job.

Just so I know. Each light will be fed via 1 flex. you will need 12 JB's and 12 Flex'.
loop the Switchline and neutral in T/E from light to light or JB to JB then flex out to each downlighter.
Don't wire all the lights in a single flex from one single JB. hope I didn't misunderstand.

thought these were no longer acceptable as theres co cable grip??

or am i having another senior moment lol

ashlys are the way to go

 

[BillyBoBob]

http://www.maplin.co.uk/images/full/vq63t.jpg thought these were no longer acceptable as theres co cable grip??

Not heard anything about that. I agree that they dont have cord grips, and I know that the choc boxes do have e'm on the lid.
If this was the case and we are still permitted to use round JB's on T/E simply because the boxes are fixed and the T/E is clipped. Would it not also be possible to use them for flex as if fitted prior to a ceiling going up couldn't they also be clipped thus solving the problem?

 

[BillyBoBob]

http://www.maplin.co.uk/images/full/vq63t.jpg thought these were no longer acceptable as theres co cable grip??

Not heard anything about that. I agree that they dont have cord grips, and I know that the choc boxes do have e'm on the lid.
If this was the case and we are still permitted to use round JB's on T/E simply because the boxes are fixed and the T/E is clipped. Would it not also be possible to use them for flex as if fitted prior to a ceiling going up couldn't they also be clipped thus solving the problem?

 

[flukey]

if they can be fitted prior to ceiling going up then maybe ok

my understanding though is if you intend pushing them back up through downlighter hole they are a no no.

will have a look later to back up that statement unless someone comes to my aid beforehand

on second thoughts if they are fitted prior to ceiling being fitted they wont be accessible so definitely a no no

 

[Risteard]

Also the Earthing Conductor is the conductor which connects to the means of earthing. There is only one in the installation. What you are referring to are circuit protective conductors.

 

[chrisgc]

Yep your good to go.
So many lights are installed in this way. I know may people like the choc boxes but I hate e'm.
I'd prefer to use http://www.maplin.co.uk/images/full/vq63t.jpg
They cost more but I think a better job.

Just so I know. Each light will be fed via 1 flex. you will need 12 JB's and 12 Flex'.
loop the Switchline and neutral in T/E from light to light or JB to JB then flex out to each downlighter.
Don't wire all the lights in a single flex from one single JB. hope I didn't misunderstand.

So its perfectly ok to use the 0.75mm HR flex cable even though the main wiring is 1.5mm.

In other words even tho I have 12 x 50w downlights the 0.75mm will be ok load wise???? (Guessing its fine as the 1.5mm twin and earth is effectively carrying the main load current).

Is that right then?

Chris

 

[Risteard]

So its perfectly ok to use the 0.75mm HR flex cable even though the main wiring is 1.5mm.

In other words even tho I have 12 x 50w downlights the 0.75mm will be ok load wise???? (Guessing its fine as the 1.5mm twin and earth is effectively carrying the main load current).

Is that right then?

Chris

What voltage are the downlighters?

 

[chrisgc]

What voltage are the downlighters?

Risteard,

The downlighters are mains D/L at 50watts.

Chris

 

[Risteard]

In that case a minimum of 1mm2 would be required.

EDIT: Actually 0.75mm2 flex may be permitted.

 

[chrisgc]

In that case a minimum of 1mm2 would be required.

EDIT: Actually 0.75mm2 flex may be permitted.

Can i be nosey and ask where your getting the info from and also to clarify 1.0mm or 0.75mm flex cable???

Also as there are quite a few lights on te downstairs circuit is it ok to upgarde the 10amp MCB for a 16amp MCB?

Chris

 

[Risteard]

Can i be nosey and ask where your getting the info from and also to clarify 1.0mm or 0.75mm flex cable???

Also as there are quite a few lights on te downstairs circuit is it ok to upgarde the 10amp MCB for a 16amp MCB?

Chris

Section 524 of BS 7671 off the top of my head.

A lighting circuit may be protected by up to a 16A device (but not higher), obviously ensuring that current carrying capacity and voltage drop are acceptable.

 

[chrisgc]

Section 524 of BS 7671 off the top of my head.

A lighting circuit may be protected by up to a 16A device (but not higher), obviously ensuring that current carrying capacity and voltage drop are acceptable.

Thanks for that kind sir.

So you think that 0.75mm flxible heat resistant cable will be sufficient for the circuit I have (12x 50w mains downlights)?

Chris

 

[BillyBoBob]

Chris Please don't use the flex for all the lights. It's concidered bad practice to wire an installation in Flex. Flex should only be used in short runs.
The last light on the end of the run will look like this................
Now at every other light you'll have two T/E on the lefthand side of the pic above.
The flex onthe right of the above pic will go to 1 single downlight and 1 downlight only.
you'll have this at all 12 of your lights.

note. the black flex in the pic is not the one I'm talking about.
And yes the pic shows the old wiring colours.

 

[flukey]

Not heard anything about that. I agree that they dont have cord grips, and I know that the choc boxes do have e'm on the lid.
If this was the case and we are still permitted to use round JB's on T/E simply because the boxes are fixed and the T/E is clipped. Would it not also be possible to use them for flex as if fitted prior to a ceiling going up couldn't they also be clipped thus solving the problem?

check out the attached link, as previously said if the jb is fixed and the cables are clipped, thats fine, as long as its accessible

if its not fixed as per downlight jb`s then they are no longer acceptable under the 17th

http://download.hager.com/hager.uk/files_download/guides/junction_box_guide.pdf

 

[chrisgc]

Chris Please don't use the flex for all the lights. It's concidered bad practice to wire an installation in Flex. Flex should only be used in short runs.
The last light on the end of the run will look like this ...................
Now at every other light you'll have two T/E on the lefthand side of the pic above.
The flex onthe right of the above pic will go to 1 single downlight and 1 downlight only.
you'll have this at all 12 of your lights.

note. the black flex in the pic is not the one I'm talking about.
And yes the pic shows the old wiring colours.

BillyBoBob,

Not using flex all through out.

All the twin and earth is in place.

BUT From the twin and earth i will be connecting this through a junction box then out of the other end of the junction box will be some flex cable (2 core preferably heat resistant) to the actual connector of the downlight (as this is double insulated).

This will of course be done seperately for each downlight.

All I am trying to find out now is if its safe to use 0.75mm 2 core flex or does it have to be say 1.0mm? The manufacturers state use 1.0mm by the way.


Also if it has to be heat resistant?

So just trying to find out what flex I can use for this part.

Also I am trying to search for 1.0mm 2 core heat resistant flex but having no luck and would be ideal if could get locally (Swindon).

So anyone know please about the flex size as some people have suggested just the 0.75mm and not heat resistant.

Chris

PS Lights are mains downlights 12x 50watts

 

[Risteard]

If manufacturers state 1mm2 then you must use it as the Regulations require you to comply with manufacturers' instructions. A cpc should also be terminated at every point.