Alarm interference

[marmite]

Hi

I want to extend the ring main within my (integral) garage. The best route is to run conduit just below ceiling height. However, half-way along my "wall of choice" there's a pattress at the end of an alarm cable (new house - alarm not yet installed but wiring already in place) where the wall meets the ceilling.

I'd like to know whether running the cable so close to a PIR and its cable is likely to cause a problem. The conduit would run immediately underneath the pattress. The alarm cable runs up into the ceiling, then horizontally back into the wall along the inter-floor space, perpendicular to the new mains cable run.

I could run it on the opposite wall, but it's a fair bit longer.

So ... 1) Is it likely to be a problem. 2) If it is, is there any simple, cheap form of shielding I could use? 3) Or is the bottom line to play safe and use the other wall?

Cheers

 

[andy]

i dont think it would be a problem, but if it is you could try STP cable for the amarm

 

[marmite]

Ta. As I say, the alarm wiring is already in place - I can't alter that.

So .... strike one for "not a problem" .... any advance?

 

[alarm_guy]

First thought... What is the "patress at the end of an alarm cable" for? If you mean that there's going to be a PIR there in future, it's a very good idea not to run mains cables near a PIR or it's cabling. Mains cabling and alarm equipment definately does cause problems. It's a bit hit and miss as to wether your situation would encounter any problems, but in general, you want to keep mains and alarms cables seperated by at least 5 inches. The PIR it's self will be more susceptible to interference. If you can, run the cable on the other wall.

 

[plugwash]

i can't see a cable just running past causing any problems

you could always use steel conduit rather than pvc though it is somewhat harder to work with

 

[breezer]

i can't see a cable just running past causing any problems

that is what most people think, but it not true.

you can get induced spikes etc going up the alarm cable if the mains cable has a heavy load etc, most alarm panels will not worry about it, however some do.

try and run the mains cables as far away from the alarm cables as posssible

 

[marmite]

alarm_guy, it's exactly as I said ... the house has pre-installed cabling for an alarm ... but no alarm; just a pattress at the end of each alarm wire where the PIR will go. But yeah, I asked the question 'cos I'd read of the potential for alarm interference on other threads - it doesn't surprise me that it may pose a problem.

I think if there's any doubt I'll steer clear ... maybe just run the conduit 18" below ceiling height or atop the skirting.

Thanks folks.

 

[HandyJon]

You should try and keep mains wire at least 6 inches away from alarm wire, and where they have to cross do it at 90 degrees only. Not an absolute rule but a guideline which should cover most eventualities.