Galvanised conduit in domestic application

[DanDIY]

I am currently fitting a new kitchen/diner. Part of the room I am going to leave as bare brick.
I was thinking that galvanised steel conduit and accesories would look quite cool against the bare brick and would make a feature of the cable run, which otherwise would be difficult to hide.

I realise that normally you would use singles down the conduit, but for a small straight run - from ceiling down to the socket, so maybe 2m, I was planning on using 2.5mm2 T&E, as per the rest of the ring.
Has anyone done this before? It will be a ring, so I would need to get 2 lengths of T&E down the conduit. Would 20mm be ok, or would I need 25mm?

Lastly, do any of the DIY places or screwfix/toolsation that are open at the weekend sell galvanised conduit, or will I have to go to a builders merchants? I can see bends, connectors etc on screwfix, but cant see any lengths of conduit.

 

[bernardgreen]

I have seen a domestic kitchen with stainless steel conduit and surface mounted sockets on brickwork. It had been well designed and looked very smart and impressive .

The supplier was http://www.electrix.co.uk/view_products.php?id=39

( There are other suppliers of stainless steel conduit and fittings. )

With any metal conduit one must allow for expansion and contraction with temperature changes, especially on long horizontal runs between sockets

 

[ban-all-sheds]

It will be a ring, so I would need to get 2 lengths of T&E down the conduit. Would 20mm be ok, or would I need 25mm?

You will struggle to pull 2 x 2.5mm² T/E through 20mm conduit. Don't have time now to go into conduit factors to see if 25mm would be OK.

Why not use singles?

Lastly, do any of the DIY places or screwfix/toolsation that are open at the weekend sell galvanised conduit, or will I have to go to a builders merchants?

Electrical wholesaler.

I can see bends, connectors etc on screwfix, but cant see any lengths of conduit.

Don't use bends - get a bending machine.

And bends or straight, don't forget you will still need a stock & die set, cutting compound and a pipe vice.

 

[ban-all-sheds]

... stainless steel conduit ...

Bet that's fun to thread....

 

[securespark]

There must be a spacing factor with conduit.

As conduit usually carried conductors with a circular cross section, I'm not quite sure how you would calculate the SF with T&E.

I would hazard a guess that 25mm would suffice, but am ready to be corrected.

 

[bernardgreen]

You will struggle to pull 2 x 2.5mm² T/E through 20mm conduit.

Two runs of 4mm twin and earth will fit easily into 20mm conduit.

Don't use bends - get a bending machine.

Agree, smooth bends look better than elbows.

As to threading stainless steel I recall it wasn't that difficult or that the supplier cut and threaded to order or the designer used stock lengths.

Galvanised may discolour in a kitchen environment. It is not permitted in commerical food production areas.

 

[sparkwright]

With respect, you will NOT struggle getting two 2.5 mm² twin and earths through 2 m of 20 mm circular 20 mm, providing you don't get twists in the cable.

As you've gathered, it's not worth the aggro using singles, as going from twin and earth cable to singles is going to problematic.

Good point made about galv not allowed in commercial kitchens, though perhaps not a problem here. Shouldn't think bare brickwork is ideal in a commercial kitchen either.

Be sure both ends of the conduit are threaded. You need a bush at the socket end, and a bush or some kind of adapter at the end where the cables first enter so they can't rub on any sharp edges.

If grouping factor is an issue, you could use two 20 mm lengths. A 25 mm length could be awkward to connect to metalclad box, as 20 mm knockouts are the norm.

 

[DanDIY]

Hi, Thanks for replies.

The room is a fairly big kitchen diner, the bit with bare brick and the conduit is about 5m away from the food preperation areas. I realise that it might corrode in time, but as long as its not really bad I think this will be acceptable.
Most of the room will be plastered with 'normal' cable runs and sockets.

I wasnt really planning on using any bends. Just a straight downpipe from the ceiling, with a small kick to get the conduit to feed into the metal boxes.

I will check the cable spacing calcs, but I seem to remember when I was at college that the actual capacity of steel conduit is virtually impossible to overload. I remember being given it as an assignment one day and you were allowed say 15 singles down the conduit, which is pretty much impossible to actually acheive.

On a similar subject. I was looking at ideas such as the following picture with bulkhead lights. Does anyone make a bulkhead light with a 20 or 25mm threaded adaptor to take conduit, or would I need to terminate with a conduit box and fit the bulkhead light close to this with a flex?

 

[Risteard]

With any metal conduit one must allow for expansion and contraction with temperature changes, especially on long horizontal runs between sockets

Actually that is a far, far, far greater problem with PVC than steel. Hence expansion couplers for PVC.

 

[OwainDIYer]

I wasnt really planning on using any bends. Just a straight downpipe from the ceiling, with a small kick to get the conduit to feed into the metal boxes.

I may be wrong as I don't use steel conduit, but I think "hospital" saddles, which space the conduit further off the wall to allow for cleaning behind, will space the conduit off the wall sufficiently so you don't have to 'set' it into the box knockouts?

http://www.electrical2go.co.uk/cabl...-conduit/25mm-galvanised-hospital-saddle.html

Lots of conduit accessories on one page for easy reference

http://www.electrical2go.co.uk/cable-management/conduit-accessories/steel-conduit.html?limit=120

On a similar subject. I was looking at ideas such as the following picture with bulkhead lights. Does anyone make a bulkhead light with a 20 or 25mm threaded adaptor to take conduit, or would I need to terminate with a conduit box and fit the bulkhead light close to this with a flex?

Many commercial light fittings will accept surface conduit eg most of these look like they do
http://www.tlc-direct.co.uk/Main_In...Bulkhead_Internal_Index/Bulkhead_3/index.html

The traditional bulkheads pictured are probably Coughtrie or copies, they come up used on Ebay (sometimes for silly prices) or you can buy new. You can form your own swan necks out of conduit if you want and then attach fittings such as
http://www.coughtrie.com/shop/pw-wall-kit-367/

 

[333rocky333]

I may be wrong as I don't use steel conduit, but I think "hospital" saddles, which space the conduit further off the wall to allow for cleaning behind, will space the conduit off the wall sufficiently so you don't have to 'set' it into the box knockouts?

Most people in general would use "distance saddles" as there more available.
As you say it also saves you setting it at the boxes

"Hospital saddles" are spaced the same but are more rounded to reduce build up of dirt sitting on the saddle, personally they look nicer but not always stocked

 

[ban-all-sheds]

Two runs of 4mm twin and earth will fit easily into 20mm conduit.

If you say so.

Looks very tight given the realities of cables twisting and kinking, particularly if there are any bends, and whilst I've not done any calculations it looks as though the % free space in the conduit is not enough.

 

[flameport]

Does anyone make a bulkhead light with a 20 or 25mm threaded adaptor to take conduit, or would I need to terminate with a conduit box and fit the bulkhead light close to this with a flex?

A majority of bulkhead lights will have 20mm knockouts where conduit can be connected. Even if not, a 20mm hole could easily be cut in the side.

Note that if using such a method, the conduit must be connected to ONE side of the light only, either as shown in the picture or using a T box adjacent to the light.

There have been installations where fools have brought the conduit in on one side, then connected another piece to the opposite side to continue to other fittings.
This is all very well until you need to remove and replace one of the lights.

 

[333rocky333]

There have been installations where fools have brought the conduit in on one side, then connected another piece to the opposite side to continue to other fittings.
.

Since the 17th edition, new reg 559.6.2 has forbidden this for most fittings

 

[ban-all-sheds]

What am I missing?

AFAICS, the problem created by the foolishness described by flameport is how the hell do you undo the conduit without starting from one end and working forwards or backwards?

Nothing to do with "through wiring".