Are two wire strappers still allowed?

[ericmark]

Looking in my old copy of the on-site guide it warns about interference with the induction loop formed if phase(s) and neutral or switch feeds and switch wires are not close together.

It continues that this can occur when a conventional two-way circuit is installed. And says how this can be reduced by connecting as shown in Fig 7.3.4 I show this below.

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• ericmark
• 7 Mar 2012
• 1

However it does not refer to any regulations although my copy is old Amd No 1 2002 for 16th Edition.

Is there a regulation to stop borrowing a line from an adjacent switch or is it still just this note in the on-site guide?

I have seen many times since the 17th came out problems where as a result of borrowing a line plus splitting lights across two protective devices that a borrowed neutral situation has resulted. Clearly this is not permitted.

But where a single protective device is used is the use of two wire strappers outlawed or just not recommended? I have looked in old 17th Edition and can't find anything to say it's not allowed.

 

[Adam_151]

IIRC, theres something in the EMC section of AMD1 - 2011 about it, but AFAIK it does not prohibt it, but rather requires that the effects of not keeping outgoing and return currents adjant be considered. The designer should be looking to avoid it in public buildings with deaf loops, etc , but it may be deemed ok for a domestic house.

 

[OwainDIYer]

it's been good practice since the 1950s to keep the wires together to reduce eddy currents.

 

[ericmark]

I would not use the two wire method if I could avoid it. One could not be sure if there were any ferrous holes created and it can also produce mains hum.

But I could not find anything saying you must not use it. And I did not want to tell others how to do it if it's been outlawed. Neither do I want to say don't do it if it's acceptable.

It is too easy to jump in with both feet and make a incorrect statement like all sockets must be RCD protected. We know most sockets must be RCD protected but a slightly incorrect statement could cause heated arguments when some one reads it as gospel.

So I was looking for a regulation but could not find one. Just the reference in the on site guide.