6 x Garden lamps on decking

[maax555]

Hi all, i am looking to fit 6 bollard lamps 240v @ 40w on top of decking. The decking is raised around 500mm from ground level.
I will be running in an armoured cable to a ip65 switch which is going to be on the decking via a post of some sort.
My question is this, as all of the electrics from the switch box are under decking can i simply use 2.5mm Twin and earth with out any protection if I hang/attach to underside of decking?
This would come straight from the ip65 switch to an ip65 junction box under the decking and feed 3 of the lamps. A 2 metre run would need to go underground to the other side of the decking or I could simply run around the decking which would use up about 10m extra cable but would avoid having to lay it underground. This would terminate in another ip65 junction box then 3 cables to each lamp.
Do i need to use two junction boxes or could i simply link from one to the next as they are only 800mm apart?
Finally the lamps only come with a standard 3 way connector block which is not waterproof. This connection will be in the middle of the stainless steel post about 100mm up from decking. Will this be ok as it is or should i use glued heatshrink over the top or even consider 6 ip65 or similar connectors?

Any advice and help appreciated.

 

[phatboy]

I would go for 12v lamps to be honest. I used them, which are safer in case of a fault, and smaller cable to run (If LED's, which I assume it would be?)

 

[maax555]

Hi No, they are E27 energy savers (i think) but def not LED.

Actually I think I would get away with 1.5 T&E for 6 x 40w?

 

[EFLImpudence]

I would go for 12v lamps... ...and smaller cable to run

That's not strictly true.

They actually require twenty times larger cable - csa wise.

 

[phatboy]

I would go for 12v lamps... ...and smaller cable to run

That's not strictly true.

They actually require twenty times larger cable - csa wise.

You didn't quote the critical part of my post though!

 

[EFLImpudence]

 

[winston1]

[quote="maax555";p="3101136"

Actually I think I would get away with 1.5 T&E for 6 x 40w?[/quote]

1.0mm T&E is all that is required for lights.

 

[JohnW2]

I would go for 12v lamps... ...and smaller cable to run

That's not strictly true. They actually require twenty times larger cable - csa wise.

You didn't quote the critical part of my post though!

Everyone's a little correct, I suppose! Although he's a bit out of the right ballpark, EFLI seems to at least be in the right direction. If, for the sake of illustration, one assumes that we're comparing the 40W 230/240V lamps with 5W 12V LEDs, that's 8 times less power but ~20 times less voltage - so the current for the LEDs would be about 2.5 times greater than for the 240V ones. So, if current-carrying capacity were the issue, then nothing like '20 times larger cable', per EFLI, but certainly not 'smaller cable', per phatboy, either

However, VD is really the issue, and if one wanted to achieve the same percentage VD, then even EFLI would be seriously under-estimating how much fatter the cable would have to be for the LEDs. With the above example (40W @ 240V vs 5W @ 12V), the resistance/metre of the cable hence, roughly, CSA) would, by my reckoning, have to be 50 times greater for LEDs in order to get the same percentage VD!

Kind Regards, John

 

[maax555]

Hi Winston (and others), yes to 1mm. The reason I mentioned those two particular wire sizes is I have a reel of both. Lol my apologies for expecting people to read my mind.

So would it be really bad of me to use this cable unprotected under the decking. I know it would work but dislike the cowboy tag it may attract.
Also would the unprotected connections inside the stainless steel tube suffer from the moisture that would occur?

Thanks again.

 

[winston1]

So would it be really bad of me to use this cable unprotected under the decking. I know it would work but dislike the cowboy tag it may attract.
Also would the unprotected connections inside the stainless steel tube suffer from the moisture that would occur?

Thanks again.

Probably would not comply with the rules but it would seem a sensible thing to do to me.

I doubt if there would be a moisture problem but to be safe you could cover them with silicon grease.

 

[DaftPunk]

How can something that doesn't "comply with the rules" ever be described as a sensible thing to do?

 

[maax555]

Ok guys, so what are the rules specific to my requirements?

 

[JohnW2]

How can something that doesn't "comply with the rules" ever be described as a sensible thing to do?

I wouldn't want to encourage (particularly 'in public') anyone to deliberately fail to comply with rules but, as for your actual question, is not the answer "When the rules are less 'sensible' than what one is proposing"?

Kind Regards, John