emergency lighting and boiler question.....

[tom_tom]

hi all..after made redundant just before christmas ive finally found some more work and need to ask a few questions before i start to make sure i get off on the right foot

basically i havent done emergency lighting much as im mostly a house basher but am i right in saying with emergency lighting its a normal 2core and earth to the 1st light then a 3 core from there on with connecting the extra feed together theres the emergency fitting? and how do i incoporate the emergency key switch into it?

and the boiler question ive connected up a new boiler on its own supply but only using the 3core flex to the spur to switch it on and off ive run a seperate 3 core from the spur to a stat which i havent connected up yet as i was going to replace the 3core with a 5 core the thing i have is what core do i put in ls and lr ( i think thats wat it said) any help would be appriciated..the boiler is a worcester bosch combi with a built in timer, hope this helps

 

[electronicsuk]

basically i havent done emergency lighting much as im mostly a house basher but am i right in saying with emergency lighting its a normal 2core and earth to the 1st light then a 3 core from there on with connecting the extra feed together theres the emergency fitting? and how do i incoporate the emergency key switch into it?

There's no set rule, it's up to you how you design the circuit and it will depend on the installation in question. You might decide, for example, to take 2C+E from the permanent supply of a local light fitting down to a test switch with N/E linked through and L through the switch, back out on another length of 2C+E and onto the fittings. The L supply will then be broken by the test switch, and only 2 core & earth required to link between fittings. If you are installing switched maintained luminaires then you'll need an extra core to do the switching.

and the boiler question ive connected up a new boiler on its own supply but only using the 3core flex to the spur to switch it on and off ive run a seperate 3 core from the spur to a stat which i havent connected up yet as i was going to replace the 3core with a 5 core the thing i have is what core do i put in ls and lr ( i think thats wat it said) any help would be appriciated..the boiler is a worcester bosch combi with a built in timer, hope this helps

I'm a little confused here. You will need at least 5 core flex for most boilers, this covers L-N-E supply, and then LS and LR for the stat. There is no need for 5 core to the stat itself unless it has a timer or requires LS, LR, N and E connections, perhaps if it has a built-in anticipator heater or similar.

What you can do is change the 3C between the spur and the boiler to 5C, wire up L-N-E as usual, and then connect the two spare cores to LS and LR at the boiler, in the backbox for the spur you can then join these using a couple of terminal blocks onto the cable you've installed for the stat.

Some older boilers did simply require the entire supply to be switched, but I doubt you'll find a modern unit that will operate that way, as they all need to run pre-flight checks as soon as power is restored.

 

[tom_tom]

brilliant mate cheers for the quick reply, would it matter what order i put the 3 core in the stat to match up with the LS and LR i mean would LS be (1) and LR be (2) for example??

 

[electronicsuk]

brilliant mate cheers for the quick reply, would it matter what order i put the 3 core in the stat to match up with the LS and LR i mean would LS be (1) and LR be (2) for example??

If the thermostat only has two terminals then no, the order is unimportant. If there are more terminals than that, you need to refer to the instructions. Also, you should sleeve any live conductors in brown, i.e. both cores at both ends that go to the stat.

 

[tom_tom]

yeh sorry wrote that without thinking theres 4-5 terminals from what i can remember. its a universal honeywell and im again from what i remember it said use terminals one and three so where do i put the 3rd core? sorry to be a arse!

 

[Taylortwocities]

The stat may need a neutral. Thats your third connection.
Many stats need this to switch accurately when temperature changes.

 

[electronicsuk]

The stat may need a neutral. Thats your third connection.
Many stats need this to switch accurately when temperature changes.

Of course, you still can't use three core if you need a neutral at the stat, as that would mean using the earth core as a line conductor.

 

[Adam_151]

Of course, you still can't use three core if you need a neutral at the stat, as that would mean using the earth core as a line conductor.

I'm sure you know what you mean, but

You *do* use three core (and earth) when the stat requires neutral, what you cnanot do is use twin (and earth) and abuse the earth as a live conductor

 

[electronicsuk]

Of course, you still can't use three core if you need a neutral at the stat, as that would mean using the earth core as a line conductor.

I'm sure you know what you mean, but

You *do* use three core (and earth) when the stat requires neutral, what you cnanot do is use twin (and earth) and abuse the earth as a live conductor

If you look back at the OP you'll see that he's wired up the stat in flex. So by that same token, you're telling me that we shouldn't be calling 3-core flex, for example, by that name - it should be two core (and earth)? Semantics...