Weatherproof box as a junction box

[Donkmeister]

Still planning the rewire!!!

I want to use a weatherproof box at the junction where "indoor" wiring meets "outdoor" wiring.

I'm going to be putting in some outdoor lights and a couple of pond pumps. What I am planning on doing is using a grid switch by the back door to control the various features.

From the grid switch, I was planning to run singles down and through the wall into the back of a weatherproof box. Inside the box, these singles would connect to the exterior cables.

That way I can wire the switches etc. once on the indoors, and as needs change in the garden I can assign (pre-wired) spare switches accordlingly. All accessories will be fused accordingly, on a second grid directly below the first, accessible but concealed within a cupboard.

If this is all acceptable, then I won't have to wire thicker, less flexible outdoor cables within a grid.

Questions:

1) Is the weatherproof box approach right, or is there a more elegant solution that still allows for future flexibility?
2) Are SWA and Hi-Tuf the only cables suitable for outdoor fixed wiring? SWA seems like overkill for supplying a low-energy PIR light, where it's going to be visible on the wall so not prone to digging etc! Plus terminating would be an issue...
3) When joining the "indoor" wiring to the "outdoor" wiring inside the moulded box, should I be using choc-blocks, or is there a more satisfactory way of doing it? Bearing in mind I want the joint to remain accessible and workable so I can reassign switches in future.

(BCO will be notified before I start work)

 

[ban-all-sheds]

If this is all acceptable, then I won't have to wire thicker, less flexible outdoor cables within a grid.

It's fine - just remember that you can't directly bury singles - they need to be in conduit.

1) Is the weatherproof box approach right, or is there a more elegant solution that still allows for future flexibility?

You've got to join the cables somewhere, and in something you can fit glands to - what is it you don't like about the weatherproof box?

2) Are SWA and Hi-Tuf the only cables suitable for outdoor fixed wiring?

You could use arctic flex, but the colours are unfortunate.

Or singles or T/E in conduit, but you'd still have the termination issue.

Q to all - what about black TRS flex?

SWA seems like overkill for supplying a low-energy PIR light, where it's going to be visible on the wall so not prone to digging etc!

Low-energy is irrelevant - there's still 230V in the cable...

Plus terminating would be an issue...

I assume you mean terminating at the light?

3) When joining the "indoor" wiring to the "outdoor" wiring inside the moulded box, should I be using choc-blocks, or is there a more satisfactory way of doing it? Bearing in mind I want the joint to remain accessible and workable so I can reassign switches in future.

How many circuits/cables/joints will you need? Many IP rated JBs have integral terminal strips, but you'd need to check they have enough ways.

It's surprising how much room choc-block takes up, and a box full of chunks of it can become unruly - screwing a strip in place would be better, but then you've got the IP rating to maintain. Maybe looking for a small box with a rail in it so that you can use rail-mounted terminals would be a good idea.

 

[Donkmeister]

I've got nothing against weatherproof boxes, but in my experience there's usually a correct way and a "more correct" way to do things... As a diyer I'd prefer to do the more correct way.

I assume you mean terminating at the light?

Certainly. I'd presume that unless the light had a means to gland, I'd have to use a box plus a length of outdoor flex anyway...

Rail-mounted terminals sound good, would provide yet further future upgrade options (timers, perhaps)

I'm going for a 12-way grid, so would like to accomodate 12 feeds in the weatherproof box... I don't fancy sticking lots of neutrals into one terminal (even though they are all on the same circuit), so I need a minimum of 24-ways inside the box. I realise most (all?) outdoor lighting is double-insulated now, but I would also like to accomodate earth in case it is required later (outdoor socket, perhaps).

 

[ban-all-sheds]

So you'll need something large enough to take 13 glands (1 incoming conduit one, pretty large as it will have 25 or 36 cables in it, depending on how you do the cpcs) and 12 outgoing ones, some or all of which may be SWA glands, but in any event will need 20mm holes. And of course they should all be on the bottom surface of the box.

And then inside you'll need enough rail space for 24 terminals, plus several earth ones, and room for timers, and who knows what else in the future? Some contactors? ELV transformers? PLCs ( )?

I'd advise one of those grey waterproof steel enclosures (or stainless if you want to be flash, and think you'll be able to cut holes in it) - Sarel and Gewiss are the makes that spring immediately to my mind, but there are lots of others.

This sort of thing:

You'll need a backplate for it (often a separate optional accessory) so that you can fix things like rails without having to drill the enclosure.

eBay is a good place to pick them up cheaply if you don't mind waiting for the right sort of size to come up - set up a saved search.

 

[Donkmeister]

Ah, I didn't realise all the glands had to be on the bottom of the box... I thought that, assembled correctly, the glands maintained the IP-rating of the box at any orientation...

Also I had been assuming (perhaps incorrectly) that it was possible to have the cables enter from the rear of the box (i.e. come out through the wall). Am I incorrect with that as well?

As it's easier to drill all the holes before putting the box on the wall, do they do some sort of blanking plate for SWA gland holes? Or should I install glands in all but leave the plastic sleave intact on unused ones??

Glad I asked now rather than after the BCO tells me it's wrong and needs redoing!

 

[breezer]

Provided you have the correct glands, and the cable isthe correct size for the glands you can put them any way up you like and they will still retain their IP rating. (Have you ever seen a waterproof cable connector? guess what it has on each end?)

BUT if you have a box with 12 glands on it it is best to put them on the bottom because if you have one cable that is the wrong size for the gland, it will let in water, and the most common reason is..

wait for it








They look silly (they really do)

I would also like to ask since you will be having 12 cables coming from this box, how are you going mechanicaly to protect them?

and do you really need 12?

if its for a pond you wont want anyone switchinbg off the filter pump and uv will you, so why not have a smaller box, less cables and run a separate feed to a smaller box adjacent the pond?

 

[Donkmeister]

Do I need 12? Well, the list of circuits I've currently got is:

Fountain pump (separate to filtration system, so want to switch it)
Pond lighting
4 sets of lights (want to separately switch them for mood purposes)
PIR lights
Tree lights (for Chrimbo)
Butt pump (hehe)

That makes 9, but like I said I want future expandibility. I don't fancy decentralising it, and multiple boxes would look scrappy. Perhaps I just need a very big box...

Thanks for all the help and advice!

 

[hairyben]

My two bob hap'ney:

I'd be tempted to go with something like a couple of wise-box

http://www.wisecontrols.com/wisebox/receivers_wisebox_4_channel_10_amps.htm

Could run a single power circuit round the garden, spur off it with localised receivers where nessecary, and all controllable from central or multiple points. And expandable.

 

[breezer]

Thats very novel looking kit.
however like most novel things it has a price tag which is a bit "ouch" but ok, but then when you start to add all the other bits that you will want, it then becomes, "er, no thanks i dont like the colour" (any excuse not to buy it)

it does look very good, but for a diy job, no.

oh, the 4ch box and switch is £122.75 may be a few £ less else where but.....

 

[sjwkmje]

I've got nothing against weatherproof boxes, but in my experience there's usually a correct way and a "more correct" way to do things... As a diyer I'd prefer to do the more correct way.

I assume you mean terminating at the light?

Certainly. I'd presume that unless the light had a means to gland, I'd have to use a box plus a length of outdoor flex anyway...

Rail-mounted terminals sound good, would provide yet further future upgrade options (timers, perhaps)

I'm going for a 12-way grid, so would like to accomodate 12 feeds in the weatherproof box... I don't fancy sticking lots of neutrals into one terminal (even though they are all on the same circuit), so I need a minimum of 24-ways inside the box. I realise most (all?) outdoor lighting is double-insulated now, but I would also like to accomodate earth in case it is required later (outdoor socket, perhaps).

With outside lights the method I prefer to use on non commerical jobs is to use swa then a 20mm galv 1 way conduit box with the lid with a thread in it to fit a stuffing gland to it. Sorry cannot remember of the lid. Use the galv box to term the SWA then use black flex to the light. This is if I cannot get directley inside to drill a hole through the wall and mount a spur the other side.

One of these:

Edit:

Found it: http://www.tlc-direct.co.uk/Products/CO20DP.html

One of these. You need to use all the glands for the galv box etc and silicon round the gland when screwing it in. Never had one of these setups leak in water yet and I have been back to a few to replace the lights when they have failed. I tend to use ferrules and wago screwless terminal blocks to do the connections as well as its all maintainence free.

 

[breezer]

2 dome plates, bit of conduit, hey presto, great clothes hanging rail

 

[hairyben]

Thats very novel looking kit.
however like most novel things it has a price tag which is a bit "ouch" but ok, but then when you start to add all the other bits that you will want, it then becomes, "er, no thanks i dont like the colour" (any excuse not to buy it)

it does look very good, but for a diy job, no.

oh, the 4ch box and switch is £122.75 may be a few £ less else where but.....

It'll tally up, but save a lot of work, and significant other costs.

Instead of having the gridswitch, large terminal box, then all the armoureds to everywhere You run a decent power supply round the garden with 2 or 3 wise box local to what you want to switch, you could even use the supply for sockets too, spur your wise-boxes off it and economise that way. As the wise-box are local, eg one by the pond, you could then run flex straight into kopex and to the pond for the pond lights, pump etc, saving armoured cable, glands etc.

Granted, DIY time is "no cost" as opposed to trade, but it's still worth looking at, and not necessarily loads more money, once you've saved the terminal box, gridswitch, armoured, glands, that all adds up.

Plus you can do things like have an extra remote just for lights so 'er indoors doesn't get too confused by master control, etc.

 

[pukka]

how about some thing like this

http://www.homeeasy.eu/product3.php

they do a out door unit with a remote switch.

Paul