MikeSharp01 Posted October 12, 2017 Share Posted October 12, 2017 I built the distribution panel today, see below. The other cables are external and while the two leaving for the garden room and house are SWA there are two 25mm tails coming in the from meter box via the main isolator in the meter box, directly behind this panel, and I am wondering of I need to mechanically protect them in trunking or some such? Also I have stripped back the tails I have used in this panel far enough to ensure you can see the cable colours outside the housings of the switches etc - it feels like the right way to do but is this the right way to do it? Link to comment Share on other sites More sharing options...
PeterW Posted October 12, 2017 Share Posted October 12, 2017 I was advised on here I think to go for twin Henley blocks rather than the double decker ones as if the casing cracks you’ve got a 100a nightmare waiting to happen ... Link to comment Share on other sites More sharing options...
RichS Posted October 12, 2017 Share Posted October 12, 2017 My sparky is just sorting out my electrics and he mentioned today that the tails between cabinets would need to be in a short length of 32mm conduit (i.e. waste pipe). Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 12, 2017 Author Share Posted October 12, 2017 7 minutes ago, PeterW said: I was advised on here I think to go for twin Henley blocks rather than the double decker ones as if the casing cracks you’ve got a 100a nightmare waiting to happen ... Hmmmm.... If they are dangerous why are they for sale? The single ones are the same material. What would the failure mode be, the whole internal barrier, cracks and falls away allowing the two blocks to come into contact? I guess I could change over to the single ones. 10 minutes ago, RichS said: My sparky is just sorting out my electrics and he mentioned today that the tails between cabinets would need to be in a short length of 32mm conduit (i.e. waste pipe). I think I will use flexible conduit as the two units are back to back through a 100mm block wall. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 12, 2017 Share Posted October 12, 2017 (edited) Double decker Henlys are legal but a bloody nightmare waiting to happen, IMHO. Do NOT leave exposed single insulated cable at all, it MUST be double insulated into the enclosure. Use tape or sleeves around the outer sheath to denote whether the cable is line or neutral, either brown and blue (preferable) but red and black is still generally accepted. Labels wrapped around the tails, with the lettering "L" and "N" is also acceptable. This is most definitely Part P work in England and Wales, and cannot be done as a DIY task, unless under the direct supervision of a suitably qualified person. Yes, some of it is nonsense, but there are gotcha's in the regs and it's the electrician who signs off the work that will get it in the neck if things aren't done correctly. Yes, the tails between the cabinets need physical protection, too, the outer sheath is not specified for exposure, so needs protecting. Worth getting a copy of the current edition of BS7671, and, far more useful, a copy of the OSGs, that translate BS7671 into plain English. Edited October 12, 2017 by JSHarris Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 12, 2017 Author Share Posted October 12, 2017 29 minutes ago, JSHarris said: Worth getting a copy of the current edition of BS7671, I have this - and was today reading the briefing on the changes for the upcoming edition next year. I was referring to section 412 (412.1.2) in doing the internal wiring but as you need to strip the outer double insulation off cables going into socket terminal etc I thought the same would apply here - there is no corresponding part 7 so no derogation. However I was not sure so I hence my question, I was happy to adjust it all but will now rewire it anyway as two henry blocks will not allow me to reuse the tails I have. I guess its the openness of the panel that makes the difference which I think means that inside the CU I do not have to take the Double insulation right up to the terminal and as long as it is double insulated through the switch cover boundaries it can be single insulated for the few mm up to the terminal. I have the shrink wrap for other bits of the installation and will use it here as well. I will do some sample connections and get chapter and verse before I start though. The installation will be checked by my brother in law who will make all the final connections, check my work, and certify the installation. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 12, 2017 Share Posted October 12, 2017 The general rule of thumb is that any line or neutral cable within an easily accessible location must be double insulated, with the guidance being that the inner layer of insulation should not be able to be touched on the outside of the switch/henly/meter enclosure by a finger or conductive tool. Link to comment Share on other sites More sharing options...
ProDave Posted October 12, 2017 Share Posted October 12, 2017 I too don't like the double deck Henley's. Just one thin web of brittle plastic separates them. I much prefer two singles side by side, some makes even interlock when so arranged, but much more substantial separation. But they are in now so I would leave them. You are not supposed to strip the outer sheath outside the enclosures. If you want to check the colour you take the cover off. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 12, 2017 Author Share Posted October 12, 2017 (edited) 35 minutes ago, JSHarris said: The general rule of thumb is that any line or neutral cable within an easily accessible location must be double insulated, with the guidance being that the inner layer of insulation should not be able to be touched on the outside of the switch/henly/meter enclosure by a finger or conductive tool. Thanks Jeremy & Dave I will get the two Henly blocks tomorrow and rewire it without the exposed colours and use shrink wrap colour marking instead. Edited October 12, 2017 by MikeSharp01 Forgot to thank Dave Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 12, 2017 Share Posted October 12, 2017 If you have a labelling machine, it's acceptable to just print labels and wrap them around the tails, clearly showing L and N. This seems to be the preferred technique of quite a lot of the meter monkeys now, whereas for years just a bit of coloured electrical tape around the tails has been the most common method. I'd already prepped ours using brown and blue tape around, but the meter monkey fitted printed labels as well. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 12, 2017 Author Share Posted October 12, 2017 I don't have a label printer but I could get one, any recommendations? Link to comment Share on other sites More sharing options...
Onoff Posted October 12, 2017 Share Posted October 12, 2017 1 hour ago, MikeSharp01 said: I don't have a label printer but I could get one, any recommendations? I've a Dymo Letra Tag here you're welcome to borrow. If buying one now I'd get this from Staples: http://www.staples.co.uk/labellers/cbs/200043995.html Half the price compared to Screweys. Link to comment Share on other sites More sharing options...
PeterW Posted October 12, 2017 Share Posted October 12, 2017 I’ve got a Dymo from Amazon - less than £20 I think delivered. Only replaced the old one as the batteries leaked into it ! Link to comment Share on other sites More sharing options...
Onoff Posted October 13, 2017 Share Posted October 13, 2017 This is a useful bit of kit: http://solutions.3m.co.uk/wps/portal/3M/en_GB/ElectricalMkts/ElectricalSupplies/products/cable-identification/scotchcode-wire-marking/ The Scotchcode dispenser takes little reels of pre printed numbers or indeed phase "numbers". The basic dispenser comes with 0-9. You can then get the L1, L2, L3, N & E pack. Try CEF just down by TP in S'oaks. There's also a new Neweys too opposite Screweys...or eBay! Link to comment Share on other sites More sharing options...
Onoff Posted October 13, 2017 Share Posted October 13, 2017 Thinking about it the tape the meter monkeys is wider as in bigger numbers... http://solutions.3m.co.uk/wps/portal/3M/en_GB/ElectricalMkts/ElectricalSupplies/products/electrical-tapes/marking-tape/temflex-1700p-printed-phase-marking-pvc/ Link to comment Share on other sites More sharing options...
ProDave Posted October 13, 2017 Share Posted October 13, 2017 the meter monkeys round here just seem to use a white sharpie and don't always get it right 1 1 Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 13, 2017 Author Share Posted October 13, 2017 1 hour ago, ProDave said: The meter monkeys round here just seem to use a white sharpie and don't always get it right ooher .... And there is me rewiring mine today. I will get the color codes right though. I notice the earth there and was reading yesterday about the new earthing arrangements coming in the 18th Edition - looks like we might all need our own earth stake! Link to comment Share on other sites More sharing options...
ProDave Posted October 13, 2017 Share Posted October 13, 2017 Just to be clear. In my picture those are insulated AND sheathed cables, it's just what the cable the DNO's use up here have colour coded sheaths. It was the markings with the sharpie that he got wrong. I have installed my own rod already. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 13, 2017 Author Share Posted October 13, 2017 6 hours ago, ProDave said: Just to be clear. In my picture those are insulated AND sheathed cables, it's just what the cable the DNO's use up here have colour coded sheaths. It was the markings with the sharpie that he got wrong. Yes - I thought as much. I have another question or two for you Dave, sorry. In this topic you posted a picture of your meter box and you have same switches that I have but I notice you have put the incoming at the top although on mine the Lin Nin are at the bottom of the switch. I understand that the electrons won't mind but is it common to use the switch in reverse direction to the labelling or is your switch labelled the other way up. If I reverse the ones I have the whole fuse assembly would be live even if the switch was off I think and there is an internal cover for the lower terminals (not in place in my photo above) to protect you if you open it live. I could simplify my cabling if I could switch the direction of one of the two switches but I guess good practice would be to have them both the same anyway. Also I took a length of the outgoing SWA apart today to see how I would run that around the panel to the top of the switches (16mm 3 core - inc Earth) I noticed that the cores are not double insulated once you split them into three so I was wondering how I handle it up to the switches given that I had in mind splitting out the earth just above the outgoing gland. @JSHarris has what looks like a solution in his meter box picture below yours in the above topic. Did you sheeth the cores Jeremy? Link to comment Share on other sites More sharing options...
ProDave Posted October 13, 2017 Share Posted October 13, 2017 Yes I stand accused. Poetic license, I know my switchfuse is wired "wrong" I would not do it like that for a customer. I would run the inner cable of the SWA up into your consumer unit intact and distribute the earths using the earth bar in the CU. Only taking the gland earths direct to your main earth terminal. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 13, 2017 Author Share Posted October 13, 2017 1 hour ago, ProDave said: I would run the inner cable of the SWA up into your consumer unit intact and distribute the earths using the earth bar in the CU. Only taking the gland earths direct to your main earth terminal. Sorry Dave, I was not clear, there are two SWA cables leaving the panel from the two switch units (one feeds the garden room and one feeds the main house) and another from the CU - which just feeds a 16A commando at the moment but will eventually feed the garden lights and the car charge point. Link to comment Share on other sites More sharing options...
ProDave Posted October 14, 2017 Share Posted October 14, 2017 The best you can do is sleeve them yourself. I used the outer sheath from some old coloured tails that were going for scrap Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 16, 2017 Share Posted October 16, 2017 On 13/10/2017 at 20:27, MikeSharp01 said: @JSHarris has what looks like a solution in his meter box picture below yours in the above topic. Did you sheeth the cores Jeremy? Sorry for the late reply, been away for the weekend with no internet access. Yes, I used grey heat shrink sleeving over the line and neutral SWA cores, where they were exposed at the point where the three cores came out of the main cable sheath. I also used a larger adhesive lined heat shrink sleeve over all three cables and the SWA core, then used a pair of needle nose pliers to form a three-way branch and seal the end of the SWA core, whilst the heat shrink adhesive was still tacky. This formed a neat termination and maintained double insulation right into the fused isolator switch. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted October 16, 2017 Author Share Posted October 16, 2017 6 minutes ago, JSHarris said: Yes, I used grey heat shrink sleeving over the line and neutral SWA cores, where they were exposed at the point where the three cores came out of the main cable sheath. I also used a larger adhesive lined heat shrink sleeve over all three cables and the SWA core, then used a pair of needle nose pliers to form a three-way branch and seal the end of the SWA core, whilst the heat shrink adhesive was still tacky. This formed a neat termination and maintained double insulation right into the fused isolator switch. Thanks Jeremy - good to see you back on line. I am thinking I will do the same but thought I might take advantage of the piranha nut not being full of the SWA gland and screw a gland down over the three tails (once sheathed) and use the gland to seal the three together although now emerging able to be separated if you get my drift. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 16, 2017 Share Posted October 16, 2017 (edited) I only ran the main insulated SWA core up inside the box to avoid having to fit long lengths of heat shrink over the cores. The central core of the SWA acts as the double insulation layer right up to the point where you strip it back to get the cores out. Edited October 16, 2017 by JSHarris Link to comment Share on other sites More sharing options...
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