ricool Posted November 5, 2007 Share Posted November 5, 2007 Hi there, I'm installing a new alarm system, there was a very old system that I have now stripped out leaving the cables in place. The person that did the original install ran the cables in trunking along side mains cables and again along side them through holes under the floors so I'm going to run new cables well away from them in new trunking etc... There is however four cables running to where the panel was in the hall which I wanted to re-use for the new one to save chaneling the walls etc... theres a cable from a light switch running in close proximity up the wall though, I have scanned the wall and its maybe a 15cm area up the wall so they may well be segregated enough. do you think this will be o.k. - I have read not to run cables next to mains but people don't give details? my thinking is that it should be o.k. as its low current not like a ring main or a cooker cable drawing a lot of current. Has anyone anyone experienced problems to do with this? - If I am to go for it what problems could happen? intermittent faults? If needs be I will channel for a new cable, the missis loves the dust! Many Thanks, Link to comment Share on other sites More sharing options...
markovitch Posted November 5, 2007 Share Posted November 5, 2007 Hi there,I'm installing a new alarm system, there was a very old system that I have now stripped out leaving the cables in place. The person that did the original install ran the cables in trunking along side mains cables and again along side them through holes under the floors so I'm going to run new cables well away from them in new trunking etc... There is however four cables running to where the panel was in the hall which I wanted to re-use for the new one to save chaneling the walls etc... theres a cable from a light switch running in close proximity up the wall though, I have scanned the wall and its maybe a 15cm area up the wall so they may well be segregated enough. do you think this will be o.k. - I have read not to run cables next to mains but people don't give details? my thinking is that it should be o.k. as its low current not like a ring main or a cooker cable drawing a lot of current. Has anyone anyone experienced problems to do with this? - If I am to go for it what problems could happen? intermittent faults? If needs be I will channel for a new cable, the missis loves the dust! Many Thanks, It can run along side it as long as the run doesnt exceed 1 metre,so i think it will be fine. Link to comment Share on other sites More sharing options...
markovitch Posted November 5, 2007 Share Posted November 5, 2007 It can run along side it as long as the run doesnt exceed 1 metre,so i think it will be fine. The problems what comes about is called induction but in this circumstance you should be ok mate. Link to comment Share on other sites More sharing options...
Guest anguscanplay Posted November 5, 2007 Share Posted November 5, 2007 They need to be a min. 100mm apart or have mechanical seperation Link to comment Share on other sites More sharing options...
kjd2002 Posted November 5, 2007 Share Posted November 5, 2007 You could just buy an interferance kit or a cheap way of doing it is connecting a 1 micro farad ceramic capacitor between the 12vDC and earth. If youve got a multimeter you could try turning it to AC an measuring between 12vDC and earth. Anything over 2-2.5vAC will cause problems. Using the capacitor should take it below this value. Hope this helps. Kev. Link to comment Share on other sites More sharing options...
arfur mo Posted November 5, 2007 Share Posted November 5, 2007 They need to be a min. 100mm apart or have mechanical seperation when 3 channel dado trunking as installed and found in million's of offices even that 100 mm separation is totally ignored, the mains is normally in the center channel with low volts stuff like telecoms and alarm cables run in the upper and lower channels. ideally the cables would be separated by 18" (in old money) to prevent induction and RFi, but in riser cupboards or in congested floor voids that is often not achieved, and even if it is later on other cables are likely to be run by others which won't comply. where ever you run your cables seperate as best you can from mains, and the trunking will keep the cables safe regarding damage, but also avoid directly laying them onto or over any pipes especially hot ones like central heating as the heat can melt the plastic and cause shorts, then it's real annoying having to take up the wooden laminate floor boards to trace it. regs alan If you think education is difficult, try being stupid!!!! Link to comment Share on other sites More sharing options...
Guest anguscanplay Posted November 5, 2007 Share Posted November 5, 2007 when 3 channel dado trunking as installed alan er that`ll be the mechanical seperator then - wont it LOL you got the mother in law round for tea again? Link to comment Share on other sites More sharing options...
arfur mo Posted November 5, 2007 Share Posted November 5, 2007 The person that did the original install ran the cables in trunking along side mains cables and again along side them through holes under the floors so I'm going to run new cables well away from them in new trunking etc...I have scanned the wall and its maybe a 15cm area up the wall so they may well be segregated enough. do you think this will be o.k. hi angus i think the separation is already covered, i responded in that vein, you seemed to be saying he needed more separation (100mm) when he has 15cm (1500mm) regs alan If you think education is difficult, try being stupid!!!! Link to comment Share on other sites More sharing options...
Guest anguscanplay Posted November 5, 2007 Share Posted November 5, 2007 hi angusi think the separation is already covered, i responded in that vein, you seemed to be saying he needed more separation (100mm) when he has 15cm (1500mm) regs alan no - you made some smart comment about multi trunking not been compliant then according to my earlier post without reading what i had put - it needs either 100mm or mechanical seperation - it`s up to the O/P to decide if they are seperated or as I read it running together for 15cms Link to comment Share on other sites More sharing options...
arfur mo Posted November 5, 2007 Share Posted November 5, 2007 no - you made some smart comment about multi trunking not been compliant then according to my earlier post without reading what i had put - it needs either 100mm or mechanical seperation - it`s up to the O/P to decide if they are seperated or as I read it running together for 15cms the point being made was not me being a smarty, it is often vaunted separation is required to prevent RFi or cross talk as is heard sometimes on phone systems when alarm cable are run close with telecom cables, to avoid that happening 18 inches is recommended seperation, when crossing mains or other signal cables it should be at right angles but in real life we know it's not always feasible. the op stated in the 1st post cables are already in trunking with mains detected 15cm away, and new cables will also be in trunking (reason for reprint) so seemed fairly aware of the situation to me, so gong into 100 mm was imo was leading him towards confusion. you as i know, very strict sparks will not allow low voltage in with mains cables in the same 18" 'channel' between joists when running through lofts or floors even if our cables are on opposite sides of that channel, yet we all happily bomb up a metal tray containment in close proximity when in risers . regs alan If you think education is difficult, try being stupid!!!! Link to comment Share on other sites More sharing options...
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