DIY help 2 way switching

[Xenolith5]

Hi all, great forum, I've found lots of help already but now I need some guidance.
I want to put two, 2 way lighting switches in our rear entrance hall. There is currently a single gang switch (2 way, common and L1 connected) but this is in the wrong place. I can run new cables and locate new switches myself but it means replacing the old switch with a blank faceplate with connections made via a choc box in the redundant backbox to the new switches. All cables will then be run in verticle and horizontal safe zones within stud / plasterboard partitioned walls. As a diy'er am I legally allowed to do this?
2nd problem!! - Local electrical shop sold me 2 core T&E instead of 3 core & earth. Is it ok to run 2 lengths of T&E using brown and blue (sheathed brown) for L1 & L2 then the brown from the 2nd T&E for the common? All wires will be sheathed brown as they will all become live at some point.

Thanks for any guidance.

 

[EFLImpudence]

Yes, you can do what you want but run the cables together (I suppose you would anyway).
I would put the spare wire in the same terminal as its accompanying other wire - for tidiness and safety.

Would it not be convenient to keep the present position as a switch as well rather than a blank?
Either way, you will need an 'intermediate' switch (this has four terminals in a rectangular formation)for the centre position.

 

[PrenticeBoyofDerry]

All cables will then be run in verticle and horizontal safe zones within stud / plasterboard partitioned walls. As a diy'er am I legally allowed to do this?

You are allowed to, but there maybe a requirement to notify the to building controls, which would depend on the location of existing and new switch (but as you state entrance hall, that would be okay) and the requirements for RCD protection are also complied to for buried cable.

2nd problem!! - Local electrical shop sold me 2 core T&E instead of 3 core & earth. Is it ok to run 2 lengths of T&E using brown and blue (sheathed brown) for L1 & L2 then the brown from the 2nd T&E for the common? All wires will be sheathed brown as they will all become live at some point.

It would be okay to use two pairs of t&e, providing all cables were identified.

You said two, 2 ways though?

 

[Xenolith5]

Thanks for replies. Cables would be run together and identified but old switch is in a useless position so will be discarded.
I'm a bit confused about the rcd. The existing switch cable runs freely inside the plasterboard wall (single storey loft to switch) protected by a 6amp mcb. Why would I need to use an rcd with new cabling when this is also run within the safe zones? I had planned to put safeplates over the cable where it is chased over the studs.

Thanks

 

[EFLImpudence]

New wiring has to be RCD protected unless other protection methods are used.

Do you have RCDs in the consumer unit?

 

[PrenticeBoyofDerry]

I'm a bit confused about the rcd. The existing switch cable runs freely inside the plasterboard wall (single storey loft to switch) protected by a 6amp mcb. Why would I need to use an rcd with new cabling when this is also run within the safe zones? I had planned to put safeplates over the cable where it is chased over the studs.

The requirements from 2008, state that RCD protection would be needed for any new cables buried in walls less than 50mm from any surface, or mechanically protected through out it's route, otherwise RCD protection would be required. So if you already have 30mA RCD protection of the circuit at the board that is protecting this circuit, you are okay. If not it would very likely to be easier changing the 6A MCB to a 6A/30mA RCBO, as it is unlikely you have a neutral where the alteration is being made and the RCD will require one.

 

[Xenolith5]

Hi - Sorry not to get back sooner to thank you for your replies. I had to go away and then got caught up in other DIY jobs!!

I'll see whether or not I can change the MCB to an RCBO.
There are a couple of RCD slots available in the CU but as you say the neutral could be a problem. Do RCBO's not need a neutral, I've never fitted one?

Thanks

 

[securespark]

Yes, they do.

They have a N flylead that connects to the N busbar. Then you connect both L & N of the circuit cable to the RCBO.

 

[Xenolith5]

Thanks for all the useful replies.
I think I can carry on now with what I've learnt!

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