Two Way Light Switching

[ban-all-sheds]

it's not at all an odd way to wire it, 3C+E is a fairly recent thing and before it's introduction most strappers were T+E, but then again most houses also had a single lighting circuit, so the neutral was already upstairs for it..

He's not got that traditional system.

The permanent live for the landing light goes to COM on the landing switch. A T+E strapper runs between L2 & L2 to the downstairs switch, and then the switched live runs from the COM of that switch back up to the landing light.

erinues - what sort of cables run between the switches, linking the L1s & L2s, and carrying the switched lives back and forth?

 

[ColJack]

do you just switch off the breaker for the light guards in a press control panel when changing one?
or do you isolate the entire panel?

same principal..

as you've said, you have no way of knowing how your house is wired, so you turn it all off before working on the electrics.

if changing a rear brake drum, do you chock the front tires to stop it roling when you jack the back wheel off the ground and take the handbrake off?

do you turn the gas off and vent the pipes before soldering a tee into the line to feed a new boiler???

 

[bogbasher]

Personally I prefer to work live anyway. Easier to build your circuits ad hoc like. You know straight away when something isnt working.

 

[ColJack]

no he hasn't BAS.. read it again..

live to common, passed to either L1 or L2 depending on the switch position then upstars the L1 or L2 passed to the Common which goes to the light....

top left one BAS..

 

[bernardgreen]

Personally I prefer to work live anyway. Easier to build your circuits ad hoc like. You know straight away when something isnt working.

And the medics like to work live too. They can't do much with a dead heart

 

[erinues]

It's perfectly safe if people adopt safe working practices.

If they are ignorant of how to do it safely, and proceed on the assumption that they aren't then they may get a nasty surprise, in the same way that if they are ignorant of how to cross a road safely, but proceed on the assumption that they aren't.

Unfortunately your analogy is chronically flawed. As an ordinary member of the public If I want to cross the road I look left and right to look for vehicles and cross if none are coming. If I want to work on an upstairs lighting circuit I go to the CU and isolate the upstairs lighting circuit and when the isolator is off I can start work. In the first case I'm safe, in the second case I'm definitely not safe.....

 

[ban-all-sheds]

if changing a rear brake drum, do you chock the front tires to stop it roling when you jack the back wheel off the ground and take the handbrake off?

Nah - got a FWD automatic - just put in Park.....

 

[ColJack]

Personally I prefer to work live anyway. Easier to build your circuits ad hoc like. You know straight away when something isnt working.

if you're going to take the **** then go away, or at least use smileys to let the idiots out there know you are joking..

it's against the law to work live unless you absolutely have to ie for reasons of life and death such as in hospitals where ventilators are operating.

 

[bogbasher]

Personally I prefer to work live anyway. Easier to build your circuits ad hoc like. You know straight away when something isnt working.

This was a joke. Dont try it at home.

 

[ColJack]

It's perfectly safe if people adopt safe working practices.

If they are ignorant of how to do it safely, and proceed on the assumption that they aren't then they may get a nasty surprise, in the same way that if they are ignorant of how to cross a road safely, but proceed on the assumption that they aren't.

Unfortunately your analogy is chronically flawed. As an ordinary member of the public If I want to cross the road I look left and right to look for vehicles and cross if none are coming. If I want to work on an upstairs lighting circuit I go to the CU and isolate the upstairs lighting circuit and when the isolator is off I can start work. In the first case I'm safe, in the second case I'm definitely not safe.....

no, the analogy is sound

by only isolating the one circuit that might provide lights, you are effectively only looking left because you think it's a one way street..

 

[bernardgreen]

What did some one once say about DIY brake repairs on cars....

Was it that it was dangerous for DIYers to do it.... ?

 

[ColJack]

if you don't know how to do it..

but with a little reading you can figure it out before you start..

the handbrake thing was something that I learned the hard way..

leaking cylinder so I took the wheel off, and tried to get the drum off, wouldn't budge, put the retaining screw back in, wheel back on, down to kwik fit, felt like a right idiot when they took the handbrake off and the drum just slid off.... never touched the brakes again

 

[erinues]

It's perfectly safe if people adopt safe working practices.

If they are ignorant of how to do it safely, and proceed on the assumption that they aren't then they may get a nasty surprise, in the same way that if they are ignorant of how to cross a road safely, but proceed on the assumption that they aren't.

Unfortunately your analogy is chronically flawed. As an ordinary member of the public If I want to cross the road I look left and right to look for vehicles and cross if none are coming. If I want to work on an upstairs lighting circuit I go to the CU and isolate the upstairs lighting circuit and when the isolator is off I can start work. In the first case I'm safe, in the second case I'm definitely not safe.....

no, the analogy is sound

by only isolating the one circuit that might provide lights, you are effectively only looking left because you think it's a one way street..

The problem I have with that argument is that a one way street is labelled as such. An upstairs lighting circuit and a downstairs lighting circuit are not labelled correctly as they are not actually for solely upstairs and downstairs.. I think that the only way way I'm going to achieve a properly safe system whilst retaining the functionality that I want is to rewire for a single lighting circuit for the house with the appropriate CSA cabling.

 

[ColJack]

can't do that, it's against the regulations unless you want to put emergency lighting in

the very fact that the switch downstairs operates the upstairs light, and that the upstairs switch operates it also, along with another light doesn't twig to you the fact that the upstairs AND downstairs are present in the upstairs switch?

a common sense test is to operate the switch before you remove the it from the wall, if something still lights up then it's not dead and you might have turned the wrong breaker off. To be honest, anyone who doesn't have the brains to try the switch before removing it deserves to get a shock... might jumpstart a few dormant brain cells..

going back to you "crossing the street" analogy, do you look left, look right and then step out?
no, you look left, look right, then look left again and keep looking left and right as you cross the road..

 

[Space cat]

by only isolating the one circuit that might provide lights, you are effectively only looking left because you think it's a one way street..

Nice one!

An upstairs lighting circuit and a downstairs lighting circuit are not labelled correctly as they are not actually for solely upstairs and downstairs..

It should be obvious that an upstairs switch that controls a downstairs light will, in all probability, have wires in it that are live if you leave the downstairs circuit on but ---

If you're concerned that some idiot might not realize this, label the switch. Put a little warning notice on it along the lines of "WARNING! Turn off power to both lighting circuits before opening this switch." Problem solved.

Or is it? If you make something idiot proof, evolution will produce a better idiot.