Argument settler

Benjamiin · Jul 20, 2015

Hi all,
I'm not new to the forum, just forgot my password so had to re register. Here's the scenario. Lights in a warehouse switch fed by one door, with strappers running round to an intermediate switch then onto another by doors 2&3, Above each door there is to be an em light. One of the lads is suggesting we run a 4 core swa between the doors so we have a neutral present, then just pinch a feed off the common of the switch. My argument is that we pull in another cable, but is there anything wrong with his suggestion? All opinions welcome. Thanks

Paul.M · Jul 20, 2015

Welcome back to the forum Ben.

(T/A)

Darkwood · Jul 20, 2015

Hi! -So our members have all the info' Benjamiin -

Are they maintained, non-maintained etc?
Are the 3 existing switches part of the local lighting or are they just a control circuit pulling in contactors which may have various lighting circuits running through them?

Deleted member 26818 · Jul 20, 2015

Why would you want to pinch a feed from the switch, if you are running a 4 core cable?

davesparks · Jul 20, 2015

If you line is following one route but your N is going via a SWA you may get a bit of an eddy current problem.

Benjamiin · Jul 20, 2015

spinlondon said:
Why would you want to pinch a feed from the switch, if you are running a 4 core cable?

Shouldve explained better sorry. There is a 3 core swa feeding one switch by main door, then the idea is to run a 4 core to the next door and then onto the 3rd, using the SWA as the CPC (complies with regs). So there will be common, l1 & l2 and a neutral present at the intermediate switch and the 3rd. One of the lads suggested taking a live off the common to a key switch to power emergency light.

Question is- is this acceptable???

Resu · Jul 20, 2015

I think it's a complete new install and they are trying to keep the materials to a minimum.

Marvo · Jul 20, 2015

Benjamiin said:
....I'm not new to the forum, just forgot my password so had to re register........

Hi Ben, what was your other username that you forgot the password to?

Benjamiin · Jul 21, 2015

Resu said:
I think it's a complete new install and they are trying to keep the materials to a minimum.

Thanks for your input, job is labour only on day rate not price. So quantity of materials and time taken does not matter to us as a firm, all I wanted was some advice as to whether this would be acceptable? Thanks

Benjamiin · Jul 21, 2015

Marvo said:
Hi Ben, what was your other username that you forgot the password to?

Hi Marvo
my old username was benroberts4 or Ben.roberts4 i think. Cheers

Marvo · Jul 21, 2015

Benjamiin said:
Hi Marvo
my old username was benroberts4 or Ben.roberts4 i think. Cheers

It was Benroberts4 and I've merged the old account with this new Benjamiin account. You have your posts back but he old account no longer exists so please keep using the new account from now on. For future reference if you forget your password you can reset it as long as you receive email on the email address you used when you joined.

Deleted member 26818 · Jul 21, 2015

Still confused.
You're running L1 and L2, but rather than using the L2, you want to take a feed from the common?

davesparks · Jul 21, 2015

Can you draw a diagram of what you are trying to explain? It's a tad confusing

Richard Burns · Jul 21, 2015

Are you saying you have a 3 core SWA as strappers between three switches and you want to replace this 3 core cable with a 4 core SWA cable and supply a non maintained emergency light near each switch position, the permanent line for each light (and the neutral) coming from the local switch?

If so this will not work as you will not have a permanent line at, at least, the last switch as this will change from L1 to L2 as the intermediate switch is operated.
Also your key switch would need to power off the normal lighting as well, which is OK and can be convenient for testing, but not easy for continued operations during testing.

You would need to replace the existing 3 core cable with a five core cable the last core providing the (key switched) permanent line for the EM lights.
However if they are non maintained then it would be easier just to run a separate 3 core cable for the emergency lights alone and leave the switches as they are.

Resu · Jul 21, 2015

I don't see why people can't understand this. If the sw and feed for the actual lights is at the first switch then it could be wired so that there is always a P live to the opposite end. If they run a 4c they will have P live (common), strapper 1, strapper 2, N & CPC. There will be a key switch for each EML fed from the P live, N and CPC. It's a little unusual but is that any reason not to do it this way?