External lighting with conduit.

[Pengwyn]

I am designing an outdoor lighting circuit with 3 lights, and involving 6 switches all run in black 20mm conduit. I might even slip a PIR or 2 in their for fun

The one thing I cannot work out is how to get the conduit to the lights themselves.

Would you terminate it to a gland then flex to light or switch rigid conduit to flex conduit and connect that way ?

Sorry if this is obvious but it has been a while since I fitted conduit and this is a refresher as much as anything.

thanks

 

[SparkyFromTheValley]

iv always used a compression gland on the end of conduit with flex running from the light to the junction box (assuming there is a junction box somewhere - usually outside the house where u have the cables going through the wall). try and have the conduit going down/across if possible to ensure no water can get through the cmpression gland over time

 

[Pengwyn]

Thanks Sparky !

I have been looking on Screwfix and cannot see any fittings to terminate the conduit into a compression gland - any advice ? I can't even see how a junction box would terminate to a compression gland.

AHH after having another look - would it be the female connector accepting a gland ?

Now that you mention it - what would be the correct way to pick up the feed through the wall into the conduit ? I would think take it into the back of a junction box and add mastic or foam to seal up but I am willing to bow to your superior experience.

 

[333rocky333]

Do you mean plastic or metal conduit
Galvanized is for outside, black enamel is more internal use.

An option is to use besa boxes and mount the light on the face of that, or use a T box tubed in the run,or similar, with one outlet used for the flex or similar to exit it to the light using suitable glands.

 

[Pengwyn]

Sorry.
I assumed the black pvc was ok for external use.
Is there a reason it's not ?

I was thinking it would be easier to use the pvc --------

 

[ColJack]

as long as there is no risk of impact damage then plastic is acceptible..

he meant the black enamel steel conduit you can get.. it's not for outdoor use and rusts like crazy if you so much as drink a glass of water within 4 feet of it..

 

[Pengwyn]

AHHHH . My mistake.

There is no risk of impact damage. It will be above head height along all of it's run except where it drops down to switches.

I am intending this to be one of my assessment jobs for NIC certification so I want it to be perfect in form and function.

Any advice would be greatly appreciated.

thanks

 

[333rocky333]

Yes, It was to do with the corrosion as coljack said.
I realised later after you mentioned female adapters, you were talking about plastic.
Not metal as I first assumed.

If using plastic I would suggest going a bit overkill with the saddles, as it tends to sag a bit sometimes.

 

[JonoPashley]

Could you not use a Conduit Terminal box and cut a 20mm hole in the lid to accept a M20 compression gland. However you can in most cases screw the gland into a female connector but i would check as this varies between manufacturers, tis all down to personal preference.

 

[holmslaw]

..

 

[nozspark]

Could you not use a Conduit Terminal box and cut a 20mm hole in the lid to accept a M20 compression gland. However you can in most cases screw the gland into a female connector but i would check as this varies between manufacturers, tis all down to personal preference.

I wouldn't cut a hole in the lid if it's external..

My preference would be a trouser box with a short bit of conduit, a female adaptor and a stuffing gland.

 

[JonoPashley]

We use a rubber sealing washer never had one leak yet.

 

[SparkyFromTheValley]

you need to use a lockin nut to secure the conduit to the junction box. drill a 20mm hole and the lockin nut will slide through the hole. it will just slot over the end of conduit nicely (they are designed for each other just ask for them at suppliers!).

MY ADVICE HERE WOULD BE: put another junction box up high near the light, then use flex and a compression gland from there.

ALSO: use white!

 

[ricewind]

Aslo if you are drilling the lid boxes to drill a small 3mm hole in the though box for drainage, as well as making sure you have the spacing fatcor worked out for the conduit.

 

[SparkyFromTheValley]

or use some silicon around the back of the box where the screws go through and around the conduit joint. i would use 1 junction box up high, using a conduit stop end to cover the hole where the wire comes through, just drill a hole in the back of it and start the conduit from there.