2 brown T&E twin and eath

[Stephen]

Hello,

I've bought some 2-brown T&E from Screwfix, their part no. 27106

Now, when cable had the old colours this used to be twin red. To tell the difference between the two red cables inside, one cable's insulation was solid red all the way to the copper conductor, whereas the other cable's insulation had a red exterior but was white inside. Thus when you cut the insulation you either saw red or white and red and could tell the two apart.

I assumed that the new reels with twin brown would be similar, i.e. solid brown and brown-white insulation.

I have just come to use the reel for the first time and both wires appear to be solid brown all the way through. How are you supposed to tell the difference without hooking up a meter? This is time consuming. Do they no longer use brown-white insulation or have I got a bad batch?

Thanks, Stephen.

[Andy Dingley]

I buzz it with an old BT cable-ident set (audio signal relative to ground). Works for long hauls too.

One way is to look at the sheath - does it have a maker's stamp on it, and is this just on one side?

PS - Screwfix cable is twice the price of TLC at the moment. Copper prices have dropped at TLC, but not Screwfix or Toolstation.

[Bob Mannix]

Sometimes the outer sheath is "handed" with a mark or protrusion on one side (or, as another poster said, the labelling may be one side only)

[Andrew Gabriel]

I don't think that was any kind of standard.

The whole point of using this cable is when you don't need to be able to distinguish. What are you using it for?

[Graham.]

When using it for 2 way light switch "strapping" I always like the switch dollies to be 'same' for off and 'different' for on, or perhaps that makes me an obsessive compulsive. IINAE

[Andrew Gabriel]

Well, I do exactly the same. If I find it's the wrong way around, I simply swap one end afterwards.

Incidently, using this cable for 2-way switching tends to imply you are generating a one turn mains coil by not having balanced current flowing in all the cables. That's generally something to be avoided where possible (can play havoc with things like hearing aid inductive loop pickup systems). It's better to use triple and earth, bringing the current from the far switch back up exactly the same path as the two strappers.

[Mike Barnes]

Same here - doesn't everyone? It's easy enough to swap the wires (or turn one switch the other way up) if the orientation turns out wrong.

Is there something wrong with that? I must be even more OCD because unless it's particularly inconvenient, I switch off using the switch that is down, so that both switches are up for off.

[<me9]

What do you compulsives do when there is an inteermediate switch?

[Mike Barnes]

There *is* an intermediate switch on our landing, and all three up is "off". One switch hardly gets used, so of course it's left up.

[Owain]

All switches up for off.

Owain

[ARWadsworth]

They walk around your house messing with various combinations of switches before smashing a wine bottle over your head and then accusing you of rape when you tell them to pack it in IME.

Adam

[Dave Liquorice]

Where do you all get you toggle switches from? Most mains switches are rocker, how do they have an "up" or "down"?

[Dave Plowman (News)]

Just a toggle with the toggle removed. ;-)

You can still tell whether they're on or off by looking - same as a toggle, although perhaps not from a distance.

[Dave Liquorice]

Doh!

I also have trouble with switches marked I and O for on or off is that off and on? And if rocker is that with that end of the rocker out or in?

[Mike Barnes]

Those switches are wrongly marked. They should be 1 and 0 (one and zero), which fairly obviously mean on and off.

You press the end marked 0 to turn off, or the end marked 1 to turn on.

[Frank Erskine]

Simple binary, innit.

[Stephen]

Sorry for the late replies.

I've only ever used one reel of this before (when it was red with red/white) so I assumed all reels were the same. I didn't realise that I had been "lucky" with my last purchase.

Can you use alignment with a makers mark though? Sometimes the cable gets twisted doesn't it. I try very hard to avoid that but if you get a twist wouldn't that switch the two cores? Are twists bad things or am I being just as obsessive as the rest of you ;)

I didn't look at TLC, though normally the p&p makes them dearer than others. I bought some copper pipe from SF and it went up just after Christmas. I wish I had bought it some weeks before when it was sitting in my wish list. Sure enough, as soon as I ordered it at the high price, it fell back to the lower price!

[Stephen]

I am using for lighting (one-way switched): to carry live from the pendant to the switch and back again as the switched live. For some reason I thought it would be important to know which was live and which was switched live but now that you've made me think about it, I can see that it doesn't matter which way round you connect them.

I've been thinking hard of a time when it might be useful to know which was which. The only thing I can think of is a 3-gang switch I once saw (not wired by me!) that had one "live" into the back of the switch which was shared between the common terminals of the three switches. The switched live had been connected by mistake so that the other lights would not come on unless the first switch was on! BTW was this a cowboy job (as I thought) or is it an acceptable way of doing things? I thought perhaps you should run three separate live and switched lives from the three separate pendants to the three gang switch?

[Stephen]

Hello again,

I googled "IINAE" but couldn't find it: is it I am not an electrician?

I couldn't understand this talk about dollies. Is that the name of the bit in the middle that does the switching? I learn something new every day!

At first this didn't make sense to me because don't their directions change depending on which switch you use to switch on and off? However I use the 3-core method for my 2-way lighting so perhaps that gives different results?

I guess if you are wiring L1 to L1 and L2 to L2, if you cross them over and wire L1 to L2 and vice versa, would one switch be "upside-down"?

When I asked this group some time ago I was advised to use the 3-core method. I never quite understood why until now. I now see with the

2-core wire the current goes in one direction from switch-switch-light, whereas with the 3-core method, the current goes from switch 1 to switch 2 and back to switch one again. Thanks AG for explaining, that's always puzzled me until now!

I'm pretty sure that with the 3-core method that if I switch s1 up the light comes on but if I then switch off at s2, s1 is still up but off; next time I have to switch s1 down to get the light on. So the switch positions for on/off alternate depending on when and where they are switched. It is a bit annoying if you are OC - and I admit to that too! - because on a 2-gang switch you can have two switches that are off but pointing in opposite directions. However I am not that OC that I choose my switches to align the rockers; I use whichever switch is nearest to me at the time.

Thanks again.

[george (dicegeorge)]

aha, a balanced current, I hadnt thought of that in thinking of stairlight switches...

Perhaps it's easier to think of a corridor with five switches,

2 cores A and B going from switch 1 to 2 ,3,4,5 and one core coming back along the same path and maybe with the switches sideways? [g]