Outdoor lights in PVC conduit ?

[maldin]

Hi,
Need to install 3 outside lights. I appreciate that SWA cable is the best option the problem is that there is very little room in the base of the pedestal lamps to bring in SWA and install a suitable jointing box. as there will be 2 incoming SWA cables and the lamp cable at two of the lamps. Could I install PVC and T&E if the conduit is buried at 50cms, warning marker cable is wrapped around full length, only straight, glued PVC conduit couplings will be used, the conduit will bent 90 degree fittings will not be used. Where the conduit exits the ground underneath the lamps it will be sealed to stop water / condensation ingress. The cables will be joined in a wagobox which will be sealed with silicone once terminations are complete. There is an RCD in the consumer unit that protects all circuits.
Thanks in advance
Mal

 

[bernardgreen]

What you propose is dangerous.

warning marker cable is wrapped around full length,

That will not be any use in warning the man with a spade to stop digging. The tape needs to be at least a spade's depth above the cable to be of any use at all.

 

[plugwash]

Really all underground cables should be protected by earthed metal (IIRC mechanical protection is an alternative but protection needs to be very substantial to prevent being dug through). PVC conduit is not sufficiant. You could possiblly use steel conduit but that is a lot of work to install.

Is there really not enough space to fit a trouser box with a couple of SWA glands in the bottom and a compression gland for the lamp flex in the top?

 

[maldin]

Hi,
The cable marker will not be wrapped round the conduit it will be laid out above the conduit, and there is an RCD. However this was only an idea. I'm happy to go along with the SWA. What if I install the lamps on a concrete plinth, pass some conduit through the plinth to allow SWA cable to pass through. As I said the problem is that there is not enough room to fit a standard weather-proof junction box with SWA glands withing the pedastal base. I toyed with the idea of laying out the cash for underground junction boxes to join the SWA with appropriate glands but then I would still have to connect in the cable from the lights which of course is not SWA and is not suitable for joining underground. If I use 3 core SWA ( ie 1 core for earth) the armour would then only be used only to prevent damage to the cable is this ok.
Incidentally the lamps were very expensive and changing them is not an option.
Mal

 

[maldin]

Hi,
What is a trouser box ?
Mal

 

[plugwash]

A trouser box is a conduit box with two entries at one end and one at the other. While primerally used for conduit work you can also screw SWA glands into the box entries. This provides a compact termination and maintains the armour continuity.

http://www.reconelectrical.com/Shop...efault.aspx?SortField=ProductName,ProductName

 

[ban-all-sheds]

Could I install PVC and T&E if the conduit is buried at 50cms, warning marker cable is wrapped around full length ...

... The cable marker will not be wrapped round the conduit it will be laid out above the conduit...

Incidentally the lamps were very expensive

But not, apparently, designed to be installed safely.

Contact the makers, and ask them to explain how they can be safely installed - if they say "consult a qualified electrician" tell them that's just what you have done, and he has said that there is no safe way to install them, and therefore no legal way, but you thought that before you went to Trading Standards and before you commenced legal action against them you would like to give them the opportunity to describe how they can be properly installed.

 

[maldin]

Hi,
Thanks Plugwash, I know these trouser boxes as conduit jointing or junction boxes usually made of galvanized steel or junk metal. I think I will go with the SWA. I will use a Wiska box to join the initial T&E as it exits the house and the SWA. I will ground the SWA using a suitable SWA gland and an earthing bar that comes as an addition to the Wiska at this location.
I will use 2 core SWA to each light. As it will not be possible to fit a SWA gland at the lights (due to space restrictions) I will need to find a suitable clamp that can be used to attach an earth cable to the armour and use a small junction box to join the cores. This project is in my own house, I'm not an electician, that's why I'm asking advice. Thanks for your input it really is appreciated
Mal

 

[maldin]

Hi Ban all sheds,
I don't have a shed, wish I did. The lamps were manufactured in the USA. In the USA they would use not use a junction box within the lamp pedestal to join the cables they would just use twist connectors which take up no space at all. They are not legal in the UK unfortunately. I believe that most outside lamps do not contain enough space to install a suitable weatherproof box, SWA cable, glands and shrouds etc within the lamp unit. If we were to inform the Trading Standards about every lamp that is not manufactured to suitable standards then it would be a full time job. I'm not an electician as I have previously said but just about every household lamp that I have come across is manufactured to specifications way way below those of similar products that would be used in industrial locations. Try buying a household lamp manufactured in the UK, you probably can't.
Mal

 

[bernardgreen]

I will use 2 core SWA to each light. As it will not be possible to fit a SWA gland at the lights (due to space restrictions) I will need to find a suitable clamp that can be used to attach an earth cable to the armour and use a small junction box to join the cores.l

Use 3 core with one as the earth to the lamps, earth the armouring but as you cannnot make the proper connection to it you cannot rely on it remaining as a good earth for the lamps.

Earthing the exposed metal of a USA made lamp is possibly more important when it is used in the UK as the unit will be designed to ope with 110 volt and the standard of insulation will ( almost certainly ) be less than the UK standards.

 

[ban-all-sheds]

The lamps were manufactured in the USA.

Are they CE marked?

If we were to inform the Trading Standards about every lamp that is not manufactured to suitable standards then it would be a full time job.

If you believe that a light is not manufactured properly then don't buy it.

I'm not an electician as I have previously said but just about every household lamp that I have come across is manufactured to specifications way way below those of similar products that would be used in industrial locations.

The regulations on buried cables apply in domestic environments just as much as they do in commercial/industrial.