2-way light switch

[Sam]

Hello,

I was reading the FAQ and the FAQ wiki and they describe two ways to wire a two-way light switch. It seems that if you are retrofitting that one way is to run 3-core and earth between both switches. However, I am wondering whether this will lead to a crowded box? After all, there will be the big 3&E, plus the live to the switch, and the cable to the lamp: so three cables in total, and three earths to fit to the box.

Is it better to use the alternative arrangement, where the live goes to one switch, the load goes to the other switch, and twin and earth is run between them? That way there are only two cables per light switch?

TIA, Sam.

[Owain]

That used to be deprecated because old switches sometimes broke down (in insulative properties) if they had live and neutral present on adjacent terminals.

Any light switch of reputable make should be able to cope with 3 x 1.5mm conductors.

Owain

[Dave Plowman (News)]

Only two cables on the most common arrangements - the triple and earth two way switch cable and the TW&E switch drop. It's not usual to bring the feed (line and neutral) to the switch as this generally wastes cable.

Generally uses more cable - not a good idea given today's prices.

Here's the circuit for a two way switch (and optional intermediate) the (my) preferred way:-

L1 L1 0===========0 0===========0============= Line | \ / | C 0================================O C \ / \ / 0===========0 0===========0============= Switch return L2 Optional L2 Intermediate

[Sam]

I just thought I should explain:

I am sure the correct way to wire a light is T&E carrying L&N to the light pendant and then T&E carrying L&switched L to the switch. However my house (1970s) has rather strange wiring. The electrician says he has never seen anything like it (but he is young LOL). It is figure of 8 with a double sheathed L and a smaller earth attached. One of these carries L to the switch and another carries switched live to the lamp, hence two wires and two earths. A separate neutral chains from one pendant to the next.

Do you think I should ask him to rewire or if it's not broke don't fix it?

TIA.

[John]

It sounds okay. I recall using the same stuff in the '70's.

[Dave Plowman (News)]

Or use junction boxes close to the fittings.

That would depend on whether the conductor sizes and insulation are up to current specs - or rather reasonable ones. I can't comment directly as I don't think I've ever seen what you describe.

[John]

Was 3/029" when I used it.

[ARWadworth]

Bog standard single and earth wiring (now called 6241Y cable). In your case you will have no permanent live at any light fitting, the lives are looped at the switches. Most of your switches should have 3 wires, a live in which is connected to the cable that feeds the next switch on the lighting circuit and a live out to your light fitting.

There is not correct way to do lighting. Loop in loop out at the pendant is usually the fastest and cheapest way of doing the job but not if you then have to fit light fittings that have small terminals.

Some councils still insist that their own houses are rewired using singles.

Adam

[Dave Plowman (News)]

Then it's pretty old and IMHO would come down to the condition of the insulation - most 3/.029 is rubber.

[Jerry]

However my house (1970s) has rather strange wiring.

Surely not in a house built in the 1970s though?

[John]

When I used it it was grey PVC. I recall buying single (double insulated) Red, Black and Red with earth at the time of doing a re-wire

[Dave Plowman (News)]

Who can tell how old the actual cable was when used?

[Dave Plowman (News)]

I've seen that. It was the figure of eight stuff I haven't. Wonder where it came from? Is it a UK made thing?

[Jerry]

Straws think clutching you I are at

Rearrange the above words into a well know phrase! :~)

[Sam]

By neutral do you mean the cable to the lamp?

I can see how there might be the "temptation" for the electricity to jump between the terminals but surely either arrangement has the live and neutral on adjacent terminals? After all, if the live and the lamp are not connected, the lamp will never come on!

[Sam]

Yes.That's exactly it.

I agree it is not how to do it if I were wiring from scratch but it would be a lot of hassle to rewire all the lights in the house. Is it best to leave them as they are?

[Sam]

I would like to use a junction box but how can you "hide" them? I think a blacking plat on the wall or ceiling would look ugly.

Thanks, Sam.

[Dave Plowman (News)]

You'd normally hide then inside the ceiling void. Not much help if you have solid floors, though.

[Dave Plowman (News)]

Jerry, I've no idea where this sort of cable originated from since I've never seen it even on sale - and I was looking at such things at that time as now. Perhaps since you're so certain it is up to the job after 40 years you'd inform me exactly what it is and who made it?

Like with all things electrical caution is the prudent way to go. Not a good idea to guess at safety.

[Owain]

No, I mean the neutral, with the possibility of a direct phase-neutral short occurring during switching.

Owain