Pocster Posted October 22, 2019 Author Share Posted October 22, 2019 14 minutes ago, Nickfromwales said: 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. ? Does your sparky fancy a trip to Brizzle ??? Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 22, 2019 Share Posted October 22, 2019 Not likely ! I already have plenty to keep him busy......for about a year lol ? 1 Link to comment Share on other sites More sharing options...
Ed Davies Posted October 22, 2019 Share Posted October 22, 2019 This is 17th Edition, still up-to-date on the spacing? Applicable to firefighter safety as well as just cable support? https://www.electriciansforums.net/threads/clips-maximum-spacing-distance.4153/ osg table 4a < 9 250 horizontal 400 vertical 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 5 minutes ago, Ed Davies said: This is 17th Edition, still up-to-date on the spacing? Applicable to firefighter safety as well as just cable support? https://www.electriciansforums.net/threads/clips-maximum-spacing-distance.4153/ osg table 4a < 9 250 horizontal 400 vertical That's the clipped direct mechanical support requirement. All the 18th has to say about the fire cable droop prevention requirement is this: 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. 1 Link to comment Share on other sites More sharing options...
Ed Davies Posted October 22, 2019 Share Posted October 22, 2019 Yep, later came across another page (from a maker of clips designed for fire protection) which basically said it was OK to mix metal and plastic clips to meet the different requirements. https://tidi-cable.com/uk/18th-edition-wiring-regulations-bs7671-changes/ Quote Plastic fixings are not banned and can be widely used throughout the industry as a cost-effective way to manage cables. However, plastic cabling fixings can no longer be used as the sole means of securing cables in place. So, I'd think that a cable clipped to, say, the side of a joist would need clips at 250mm spacing but only every third one, or something like that, would need to be metal???? Link to comment Share on other sites More sharing options...
dpmiller Posted October 22, 2019 Share Posted October 22, 2019 behind plasterboard would it need any?.. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 Just now, dpmiller said: behind plasterboard would it need any?.. It seems to be a bit of a judgement call. The intention is to support wires after ceilings etc have burned through or collapsed, so they can't drop down and entangle firefighters, so I'd say that all horizontal cable runs need fire resistant supports, that are able to prevent the cables drooping down low enough to cause a problem for a firefighter wearing BA. Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 23, 2019 Share Posted October 23, 2019 9 hours ago, dpmiller said: behind plasterboard would it need any?.. We don’t bother vertically tbh, but horizontally and especially overhead then it’s just good practice tbh. Deciding what is or isn’t an egress / escape route is a judgment call I don’t want to make. Being behind plasterboard ( ceilings ) is of zero consequence for discounting this rule afaic, but sense can prevail as to how many bands are fitted and where, but taking 90 degree bends through superstructures helps as the changes in direction will arrest the fall to some extent too. Link to comment Share on other sites More sharing options...
Pete Posted October 23, 2019 Share Posted October 23, 2019 9 hours ago, JSHarris said: It seems to be a bit of a judgement call. The intention is to support wires after ceilings etc have burned through or collapsed, so they can't drop down and entangle firefighters, so I'd say that all horizontal cable runs need fire resistant supports, that are able to prevent the cables drooping down low enough to cause a problem for a firefighter wearing BA. This change came about after two firefighter's became caught up in electrical cables that had dropped down from a suspended ceiling in a block of flats and lost their lives. The cables got trapped between their BA cylinder and the backplate and they could not get free. The Fire Service also brought in a new strap for B/Apparatus that now prevents cables getting into the narrow gap, when a cylinder is changed there is a strap that goes from the backplate to the cylinder so if a cable does drop on to this area it just slides off. 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 23, 2019 Share Posted October 23, 2019 1 minute ago, Pete said: This change came about after two firefighter's became caught up in electrical cables that had dropped down from a suspended ceiling in a block of flats and lost their lives. The cables got trapped between their BA cylinder and the backplate and they could not get free. The Fire Service also brought in a new strap for B/Apparatus that now prevents cables getting into the narrow gap, when a cylinder is changed there is a strap that goes from the backplate to the cylinder so if a cable does drop on to this area it just slides off. I remember that, and had been looking around for a photo that was doing the rounds then showing the way wires dropped down to form what looked like something Spider Man might have used to restrain people to illustrate the point here, but couldn't quickly find it. Not sure why it too so long to get included in the regs, TBH. It was in the 17th to a limited extent, all the 18th has done is make it apply to all wires and cables, I think. Link to comment Share on other sites More sharing options...
Onoff Posted October 23, 2019 Share Posted October 23, 2019 Here is the incident report: https://www.ife.org.uk/Firefighter-Safety-Incidents/shirley-towers-2010/34619 2 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 23, 2019 Share Posted October 23, 2019 Thanks, @Onoff, that's the one I was looking for. The photos of all the tangled cables that have dropped, especially those on the staircase, were the ones I remember seeing back when this happened. Link to comment Share on other sites More sharing options...
Onoff Posted October 23, 2019 Share Posted October 23, 2019 1 minute ago, JSHarris said: Thanks, @Onoff, that's the one I was looking for. The photos of all the tangled cables that have dropped, especially those on the staircase, were the ones I remember seeing back when this happened. Looks like some serious trip hazard / foot entanglement issues too. Link to comment Share on other sites More sharing options...
andyscotland Posted October 23, 2019 Share Posted October 23, 2019 20 minutes ago, JSHarris said: Not sure why it too so long to get included in the regs, TBH. It was in the 17th to a limited extent, all the 18th has done is make it apply to all wires and cables, I think. It went into 17th for access and egress routes as those were considered the highest risk, but AIUI that then prompted a lot of jumping through hoops by big developers to try to define things as not being access and egress routes to save a bit of cash. So the 18th made it apply everywhere to avoid any argument. 10 hours ago, JSHarris said: It seems to be a bit of a judgement call. The intention is to support wires after ceilings etc have burned through or collapsed, so they can't drop down and entangle firefighters, so I'd say that all horizontal cable runs need fire resistant supports, that are able to prevent the cables drooping down low enough to cause a problem for a firefighter wearing BA. AFAIK the intention is actually to support wires before ceilings have burned through : in the fatality fire the ceilings were intact, the problem was the cabling was all in surface mounted plastic trunking which failed very rapidly. My understanding is once sheets of plasterboard start raining down the firefighters will be withdrawing anyway. "Premature collapse" in this context means "while the building is otherwise structurally sound" eg the cables are not the first thing to go. Certainly cables that are passing over joists etc at fairly regular intervals are unlikely to be an issue unless the ceiling is very low. I know some of the certification scheme providers require clips everywhere (and tbh there's often no real reason not to on new build / major refurb : it doesn't hurt and isn't really that expensive in the grand scheme of things) but that is a very strict reading of both the intent and wording of the regs. Also worth noting that in some cases vertical runs may need support, depending on where they are, how much free cable is involved, and how/if fixed at either end. Although less likely to tangle BA they could still pose quite an obstruction at floor level/to other kit if they can sag too far away from the wall. E.g. I would be more concerned about a vertical surface run up to a plastic light fitting/PIR detector/WiFi access point than a horizontal run above the plasterboard ceiling. 1 Link to comment Share on other sites More sharing options...
Onoff Posted October 23, 2019 Share Posted October 23, 2019 Typical bloody council rewires done in trunking. Private customers can end up with it too mind. The wife's late aunt, very well to do and loaded had a couple of "wonderful chaps" rewire her big place. Surface mount everywhere. They went up the wall in mt, stopped at the ornate plaster coving then across the ceilings to the lamps again in trunking. Paid cash, done in a day, no certs etc. 1 Link to comment Share on other sites More sharing options...
Pocster Posted November 14, 2019 Author Share Posted November 14, 2019 Well, my fantastic sparky looked today. He said cable trays as overkill. But the metal band straps fine. I suggested strips of osb with timber either side in the roof (to act as a cable tray) or even plastic half round guttering - he was happy with both! Link to comment Share on other sites More sharing options...
Pocster Posted November 25, 2019 Author Share Posted November 25, 2019 Home made cable tray made . Strip of osb with pipe insulation at the edges . This is to stop a cable spilling over ( will also metal strap later ) - also allows a cable to deviate off the tray for a fitting . Best bit ; it cost nothing - just materials lying around . 1 Link to comment Share on other sites More sharing options...
Onoff Posted November 25, 2019 Share Posted November 25, 2019 Can you straighten that pipe lagging up please I find it offensive. Plus I hope all those cross head screws are aligned the same way. ? 1 2 Link to comment Share on other sites More sharing options...
Pocster Posted November 25, 2019 Author Share Posted November 25, 2019 4 minutes ago, Onoff said: Can you straighten that pipe lagging up please I find it offensive. Plus I hope all those cross head screws are aligned the same way. ? Did it like that on purpose to annoy you ! Link to comment Share on other sites More sharing options...
Onoff Posted November 25, 2019 Share Posted November 25, 2019 30 minutes ago, pocster said: Did it like that on purpose to annoy you ! And you can trim that patchwork Celotex whilst you're at it and foil tape the joints! ? Link to comment Share on other sites More sharing options...
Pocster Posted November 25, 2019 Author Share Posted November 25, 2019 14 minutes ago, Onoff said: And you can trim that patchwork Celotex whilst you're at it and foil tape the joints! ? You are too bloody ocd fussy ! . No wonder it takes you a week to get a tile on the bleeding wall ! 1 Link to comment Share on other sites More sharing options...
phatboy Posted November 26, 2019 Share Posted November 26, 2019 (edited) I found cable basket was way way cheaper than tray, despite being just as good. £5 for 3m I recall, for a 50x55mm one Edited November 26, 2019 by phatboy 1 Link to comment Share on other sites More sharing options...
Pocster Posted November 26, 2019 Author Share Posted November 26, 2019 4 minutes ago, phatboy said: I found cable basket was way way cheaper than tray, despite being just as good. £5 for 3m I recall, for a 50x55m one Yeah that’s true . Finished my ‘freebie’ one today . Link to comment Share on other sites More sharing options...
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