Metal Clad Switches With 25mm Knock-Outs.

[securespark]

Need a 3G grid with 25mm k/o's. Anyone know of any?

Failing that, could I convert a horizontal 25mm conduit supplying the cables to this switch into 2x 20mm drops?

Ta.

Forget this, I'd forgotten about these. http://www.tlc-direct.co.uk/Products/MTRED25slash20.html

 

[PrenticeBoyofDerry]

The MK 46mm have 25mm KOs
K8902 ALM
Not sure that any of the 38mm do have!

 

[securespark]

Thanks!

 

[securespark]

Usually, conduit would carry singles.

Do you think 25mm conduit would carry 4 x 1.5 T&E cables allowing for the spacing factor?

I think it would, but I'd like to work it out.

Unfortunately, I don't know how, mathematically.

 

[ricicle]

Overall csa of 4 x 1.5mm² t+e (including insulation) is approx. 120mm²

CSA of 25mm conduit = 490mm

45% of 490 = 220.5mm² 120 < 220.5

It will be fine.

 

[securespark]

Thank you! I thought it would be, but didn't know the exact calc.

 

[securespark]

Related to this is a switch alteration.

I'm thinking about moving a 3 gang switch from one end of the room to the other (hence the 25mm conduit and 1.5 T & E).

Already at the other end of the room is an existing 1G switch on another circuit.

I don't want to mix this wiring in one enclosure or conduit so the 1G switch will remain separate.

It is fed with galv conduit which disappears into the plasterboard ceiling.

I cannot afford to disturb it, I want the 1G switch mounted to the left of the new 3 gang and there is no room to the right of the 1G switch to be able to leave it where it is and mount the new 3G to the RHS of it.

SO, I was thinking of:

Mounting the new 3G switch (fed by the 25mm conduit) to the LHS of the existing 1G, then extending the wiring out of the 1G box through conduit to a new box to the LHS of the 3G. This would be done by dropping out of the 1G box with conduit, running a piece under the 3G box then up into the new 1G box on the LHS of the 3G.

Hope you can understand this:

Bearing in mind I cannot disturb the existing conduit or ceiling, do you think this is my best option?

 

[Adam_151]

Would look a bit odd I think Simon

I'd mount the three enclosures together with couplers and brass bushes and re-route the conductors from the single gang switch that way, with extensions crimped on if necessary.

As long as a suitable label is applied (remeber 400v label as well if on different phases) I dont see the problem and if aestehics are an issue, then label on the grid yoke instead of cover plate

 

[securespark]

Thanks.

I know it looks a bit odd, but I'm attempting to make it less confusing by keeping the circuits separate. From memory, they are on different phases, too.

One for me to ponder....

 

[ban-all-sheds]

Just do some labelling/documentation and replace the 1-gang with a 4-gang.

 

[securespark]

Thought of that, too.

Historically, this has been the set up since the place was built. So I wondered whether the 1G should stay (as everyone knows what it does) and then move the 3G (everyone knows what it does ) from one end to the other, or whether to combine the two in a 4G switch.

But think you're right. If the LH switch of a 4G is wired up to control the lights that the 1G switch operated and the other 3 wired up to operate the same as the 3G switch, then it should be intuitive.

 

[ban-all-sheds]

People will soon get the hang of it.

What about a 6-gang grid - have the original 1-gang switch moved to the LH top row, the other 2 positions blanked, and the 3-gang set on the bottom row?

 

[securespark]

Thanks. Will consider.

 

[333rocky333]

use one coloured gridswitch
Seriously use seperate boxes but space with lockrings rather than couplers