Cable trays

[thendzor]

Morning,

We are building storage warehouses and our electricians always insist on installing cable tray systems for distributing the lights saying that cable needs to be mechanically protected.

When I have questioned them if they can refer it to any standard, but nobody knows the answer...

I would prefer to distribute the cables along the bottom purlins (see below) and fix them with cable ties as this will save me a lot of money. In my personal opinion, this will be better than some thin cable tray.

Can you please advise if this can be done as I proposed and it will conform to UK standards?

Thanks!

 

[Evans Electric]

No reason why you can't do that .   I've dropped  PVC conduit , SWA  & T/E   etc   in  the purlins  .  Connect each fitting with plug-in rose , hang fittings from the bottom edge of the purlin . 

The cable needs little mechanical  protection up at those heights . 

 

[thendzor]

Thank you! I believe it is just a reason to charge more money...

What about going with the cable down to the distribution board? It will be kinda exposed but very little risk of getting damaged, do you think it should go in some type of conduit?

 

[binky]

it's considered good practice to use tray, but it's  not for mechanical protection.  You're probably only running a few lighting ccts so does seem overkill. The only issue with cable ties ( and I'm not sure this applies to industrial buildings) is that in the event of a fire, ties will melt easliy dropping cable down over walkways which can be a hazard for the Fire Brigade, so I would suggest using stainless steel cable ties at regular intervals along the cable run. 

 

[Evans Electric]

Thank you! I believe it is just a reason to charge more money...

What about going with the cable down to the distribution board? It will be kinda exposed but very little risk of getting damaged, do you think it should go in some type of conduit?

Depends on what type of cable they are using .   A warehouse  like you show would probably  need trunking rising up from the switching position  , then spanning the building . 

From the trunking various types of cable could be utilised to drop into the purlin upturn . 

 

[kerching]

You can buy a plastic capping that turns the purlin lip into trunking"..or a two least you used to be able to

 

[UNG]

You can buy a plastic capping that turns the purlin lip into trunking"..or a two least you used to be able to

I remember that and that was my first thought when I read the OP, used loads of the stuff in the past but looking round the web I don't think it is available any more, if I remember correctly I think it was called Ward Multibeam

 

[kerching]

Ward Multibeam

Thats the one

it had those little modules with a 15 connector strip in it for connecting lights

had to re jig some in an industrial unit pre lockdown S1 !

 

[tomsw18]

I've seen exactly what you're looking for installed in a Segro warehouse near Heathrow Airport and just PVC cables used.

I'm pretty sure Segro wouldn't accept this if it wasn't allowed as they are a large warehouse developer.

 

[Andy™]

I'm pretty sure Segro wouldn't accept this if it wasn't allowed as they are a large warehouse developer.

saves them a few ££ and itll be allowed. bit like every other developer

 

[tomsw18]

saves them a few ££ and itll be allowed. bit like every other developer

Sad but true.