Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 So is this mockup wrong ? Couldn’t find any cable on site for love nor money ; typically ! . Improvised with a broom ?. Did find by luck some ‘banding’ - once I saw @Nickfromwales link I knew what we were talking about . Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 48 minutes ago, pocster said: Yeah so I am correct . I just use the metal straps to fix cables to the timber ? @Nickfromwales says there’s more to it than that though . You should keep data and power cables well separated, but that's really the only restriction, other than the previously mentioned one of fire resistance of cable clips and supports. Personally I like to make sure cables are clipped to a batten or board, in a location where they aren't likely to get damaged and also where they can be seen easily for inspection, etc. Doing this in neat lines also makes it easier to identify circuits later if there's a need to change anything. There's also a max spacing between cable fixings in the regs, plus I'd not use potentially sharp edged banding as cable clips. 1 Link to comment Share on other sites More sharing options...
Triassic Posted October 22, 2019 Share Posted October 22, 2019 But! All my wiring is behind plasterboard, I’m not bothered if it sags during a fire! The house would be foobared anyway. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 Just now, Triassic said: But! All my wiring is behind plasterboard, I’m not bothered if it sags during a fire! The house would be foobared anyway. The drooping wiring bit in the regs is because firefighters have been trapped in burning buildings by the maze of wire that has dropped down, rather like a net. Doesn't matter if the house is "foobared", as the purpose of the regulation is to save the lives of firefighters, who may well have to enter a building in order to try and rescue someone that's trapped. Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 1 hour ago, JSHarris said: You should keep data and power cables well separated, but that's really the only restriction, other than the previously mentioned one of fire resistance of cable clips and supports. Personally I like to make sure cables are clipped to a batten or board, in a location where they aren't likely to get damaged and also where they can be seen easily for inspection, etc. Doing this in neat lines also makes it easier to identify circuits later if there's a need to change anything. There's also a max spacing between cable fixings in the regs, plus I'd not use potentially sharp edged banding as cable clips. Was going to keep mains separate anyway. So for my cat6 this method is acceptable? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 If it were me, then I'd run the data cable in trunking, with the trunking secured with fire resistant clips.. Take a look at something like the D Line trunking system, as they include fire rated clips. Makes the installation a fair bit easier if you're just feeding cables into trunking. Trunking: https://www.tlc-direct.co.uk/Main_Index/Trunking_Pvc_Index/index.html D Line fire rated clips: https://www.tlc-direct.co.uk/Main_Index/Trunking_Pvc_Index/Dline_SD_CLIPS/index.html More details from D Line: https://www.d-line-it.com/safed-clips/ 1 Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 22 minutes ago, JSHarris said: If it were me, then I'd run the data cable in trunking, with the trunking secured with fire resistant clips.. Take a look at something like the D Line trunking system, as they include fire rated clips. Makes the installation a fair bit easier if you're just feeding cables into trunking. Trunking: https://www.tlc-direct.co.uk/Main_Index/Trunking_Pvc_Index/index.html D Line fire rated clips: https://www.tlc-direct.co.uk/Main_Index/Trunking_Pvc_Index/Dline_SD_CLIPS/index.html More details from D Line: https://www.d-line-it.com/safed-clips/ Yeah seems good . Some of the metal cable trays are a bit cheaper though . Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 4 minutes ago, pocster said: Yeah seems good . Some of the metal cable trays are a bit cheaper though . Remember to factor in metal brackets/supports for the cable trays, though. PVC trunking can just be screwed to timber or walls directly, using metal clips to give the fire resistant support needed for the cables. Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 6 minutes ago, JSHarris said: Remember to factor in metal brackets/supports for the cable trays, though. PVC trunking can just be screwed to timber or walls directly, using metal clips to give the fire resistant support needed for the cables. True . Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 Are you allowed ‘breaks’ in the conduit ? Suppose you’ve got to pull a cable through a long run with many corners . Can you pull it to a break in the conduit ? Then pull it the rest of the way ??? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 8 minutes ago, pocster said: Are you allowed ‘breaks’ in the conduit ? Suppose you’ve got to pull a cable through a long run with many corners . Can you pull it to a break in the conduit ? Then pull it the rest of the way ??? It's normal with conduit to fit junctions that allow access, both in long straight runs and at corners: https://www.tlc-direct.co.uk/Main_Index/Conduit_Pvc_Index/20mm_Conduit_and_Fittings_Black/index.html With trunking you don't need these, as the lid comes off, so everything is just laid in the U section of the trunking, then when all the cables are in, the fire clips are bent over and the lid clipped on. Trunking still needs corner fittings, tees etc, but like the trunking itself the top comes off for access. 1 Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 3 minutes ago, JSHarris said: It's normal with conduit to fit junctions that allow access, both in long straight runs and at corners: https://www.tlc-direct.co.uk/Main_Index/Conduit_Pvc_Index/20mm_Conduit_and_Fittings_Black/index.html With trunking you don't need these, as the lid comes off, so everything is just laid in the U section of the trunking, then when all the cables are in, the fire clips are bent over and the lid clipped on. Trunking still needs corner fittings, tees etc, but like the trunking itself the top comes off for access. I see . So ( to comply with regs ) I need to come off my timber to get the cat cable to where I want it does it still need to be in conduit at that point ? ( e.g ceiling centre 300mm away from the timber structure) Hope my question is clear Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 (edited) Another dumb question . As this is all for safety regs how can a pvc conduit be ok ? Metal clips attach it to the timber but during a fire would it not just collapse regardless of the cables in it ? I.e melt Edited October 22, 2019 by pocster Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 1 minute ago, pocster said: Another dumb question . As this is all for safety regs how can a pvc conduit be ok ? Metal clips attach it to the timber but during a fire would it not just collapse regardless of the cables in it ? I.e melt As long as the metal fire clips are used PVC trunking is fine. The advantage of the trunking is that it's a easy to just lay cables inside the stuff with the lid off. Means you can go back and forth with additional cables, then secure the lot when you're finished by bending the metal clips over and clipping on the lid to make things tidy and provide additional protection to the cables. Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 11 minutes ago, JSHarris said: As long as the metal fire clips are used PVC trunking is fine. The advantage of the trunking is that it's a easy to just lay cables inside the stuff with the lid off. Means you can go back and forth with additional cables, then secure the lot when you're finished by bending the metal clips over and clipping on the lid to make things tidy and provide additional protection to the cables. That sounds far easier for me as I need to add as I go and undoubtedly will forget a cable for something. Still don’t get how it can be ok in a fire situation- surely pvc would just melt - then it’s dripping molten plastic and cables falling ???? ? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 3 minutes ago, pocster said: Still don’t get how it can be ok in a fire situation- surely pvc would just melt - then it’s dripping molten plastic and cables falling ???? ? The metal fire clips stop the cables from falling. Before the changes to the regs, PVC trunking on it's own was fine for most applications, after the changes you just need to add the metal fire clips when fixing the trunking in place, so these can hold the cables up when the trunking melts. 1 Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 2 minutes ago, JSHarris said: The metal fire clips stop the cables from falling. Before the changes to the regs, PVC trunking on it's own was fine for most applications, after the changes you just need to add the metal fire clips when fixing the trunking in place, so these can hold the cables up when the trunking melts. Ok ! . Still sounds like not much fun for the fireman . So pvc trunking with the metal clips . I presume there’s a rule on minimum clip spacing ? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 5 minutes ago, pocster said: Ok ! . Still sounds like not much fun for the fireman . So pvc trunking with the metal clips . I presume there’s a rule on minimum clip spacing ? The regs just say this, so not much help! : Quote 521 .10.202 Wiring systems shall be supported such that they will not be liable to premature collapse in the event of a fire. NOTE 1: Wiring systems hanging across access or egress routes may hinder evacuation and firefighting activities. NOTE 2: Cables installed in or on steel cable containment systems are deemed to meet the requirements of this regulation. NOTE 3: This regulation precludes, for example, the use of non-metallic cable clips or cable ties as the sole means of support where cables are clipped direct to exposed surfaces or suspended under cable tray, and the use of non-metallic cable trunking as the sole means of support of the cables therein. NOTE 4: Suitably spaced steel or copper clips, saddles or ties are examples that will meet the requirements of this regulation. The intention is to prevent cables being able to droop down and cause a snagging hazard for firefighters, so I'd guess that fitting clips every 300 to 500mm or so in trunking is probably OK. 1 Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 Just now, JSHarris said: The regs just say this, so not much help! : The intention is to prevent cables being able to droop down and cause a snagging hazard for firefighters, so I'd guess that fitting clips every 300 to 500mm or so in trunking is probably OK. Ok - that sounds reasonable. But do I have to trunk right to the end spot ? . Say I have a humidity sensor I wish to place in a ceiling - do I have to trunk directly where I think I want it ? . If when I test the sensor I need to move it ; I re adjust that trunking ? . I guess I’m asking is there any Lea way for the cable going from trunking to device ? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 I'd only use trunking (or cable tray for that matter) where there are long runs and lots of cables to support, just because it makes life a bit easier when laying the cables. It's easy enough to just route short runs of cable out of the trunking to devices, sensors etc, just clipping the wires directly. 1 Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 8 minutes ago, JSHarris said: I'd only use trunking (or cable tray for that matter) where there are long runs and lots of cables to support, just because it makes life a bit easier when laying the cables. It's easy enough to just route short runs of cable out of the trunking to devices, sensors etc, just clipping the wires directly. Cheers @JSHarris ; you’ve been super helpful ! Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 22, 2019 Share Posted October 22, 2019 5 hours ago, pocster said: Yeah so I am correct . I just use the metal straps to fix cables to the timber ? @Nickfromwales says there’s more to it than that though . Distances between clips ( you need to know the regs old bean ). Who is going to sign this off? They need to witness all this and should be advising you !!! Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 1 minute ago, Nickfromwales said: Distances between clips ( you need to know the regs old bean ). Who is going to sign this off? They need to witness all this and should be advising you !!! Doesn't need a sign off - it's data cables I believe, so no Part P, but still needs to comply with the regs. It's a bit of a loophole, really, as data cables can present as much risk to firefighters as power cables (the last job I looked after before retiring had many thousands of metres of data cable in), so they need to comply with the regs as far as cable supports, fire provision, perhaps even the need to use LSF cable, yet no one has to sign the work off as being compliant, AFAIK. Link to comment Share on other sites More sharing options...
Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 7 minutes ago, Nickfromwales said: Distances between clips ( you need to know the regs old bean ). Who is going to sign this off? They need to witness all this and should be advising you !!! It is just cat cable at the moment. Trying to find a reliable cost reasonable electrician is virtually impossible. I’m hoping to do the mains wire aswell but advised and monitored by a qualified electrician who will sign it off . Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 22, 2019 Share Posted October 22, 2019 21 minutes ago, pocster said: It is just cat cable at the moment. Trying to find a reliable cost reasonable electrician is virtually impossible. I’m hoping to do the mains wire aswell but advised and monitored by a qualified electrician who will sign it off . Ok, it’s pretty much a single standard for clipping ( banding ) but as I said you can cheat if there are pozi joists and you run through the points where the two metal webs converted on the lower chord. ?. Now the 18th Ed refreshers are out and most sparks have sat it and are fluent, it’s things like this which are now getting reiterated whereas before most sparks treated it as ‘optional’ or done to attain a gold star. My lead electrician has just done his 18th / peripheral refreshers and is now ‘on point’ in all these matters of elastictrickery. ? 1 Link to comment Share on other sites More sharing options...
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