Alarm cables/mains cables

[breff]

Im with Allso on this one, I cant see how plastic can reduce a magnetic field, although Im sure your right on the standards Jef.

Even in trunking ,I would keep them at least 6 inches apart unless its for a short run.

[jb-eye]

I share rjbsec's sceptical view on this one.

It would defy the basic laws of physics for plastic trunking to remove the danger of induced AC voltages, no matter what any regulations might say!

It's the magnetic fields around the AC cable that cause the induced voltages, and I can't see how plastic would protect alarm cables from this.

Allso

Yeah maybe. I sometimes think i know more than all the IEE and PHD guys that write those EN regs. regardless though you cant go wrong if you stick with the regs. You have me wondering now about those thousands of miles of data and control cable I

[Guest scottygio]

I want to thank all for their interesting input. I understand the importance of keeping the cables separate but in this case to get the cables upstairs i only have one route (about 2.5 metres). Once i get upstairs i can separate them. For the part where they are running together for 2.5 metres how would containing the alarm cables in kopex help? Kopex is flexible metallised conduit. Would this stop the induction and does anyone know the minimum distance required between mains and alarm cable?

thanks again

scott

[Adi]

I think the best thing is to install your cable and fit a filter if you get induced ac. Kopex could help but will need to earthed, seems alot of aggro.

[Guest rjbsec]

I would still recommend screened cable - minimum distance quoted in the BS7671 referred to above is 50mm but the further apart you can make it the better.

[Adi]

Use screened alot easyer than faffing around with flexi.