MikeSharp01

How are you going to get the camera down the pipe if it is so convoluted?

+1 on the @JSHarris offered link above its a great article and has several very good references.

Ah - that makes more sense - the thickness is now 25mm greater ad the total U value of the build up (all the bits) is worked out using the process: First find the Resistivity (R1) of the frametherm portion = material thickness (d ) / Thermal conductivity coefficient (k) [Known as Lambda] then for R2 (the 25mm of PU) = material thickness (d ) / Thermal conductivity coefficient (k) add R1 + R2 to get a total R And the U value = 1/R So plucking some values for frame therm and PU the double build up is U = 1/(.025 / .022) + (.140/.032) = 0.18 while for just PU U = 1/(.140/.22) = 0.15 Much more as quoted but they will also include the sheathing board, internal plasterboard, air gaps and everything else in the build up, all of which have Lambda values and thickness.

The manufacturers numbers Sound odd given a common thickness of insulation the two / three have very different insulating characteristics. Your numbers look more in line with what might be expected.

Yes that makes sense although I want the earth out at the bottom of the panel so I guess I will have to bite the long sleeve bullet or have an intermediate earth block at the top by the switches and that would introduce further points of failure. Decisions decisions....

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.

Welcome to THE forum. Sounds like just sit tight but check there is no time limit on the CC claim.

Great fun - wonder what the lighting effect would be if you filled the jars with stewed apple, mango chutney, pickled onions and marmalade.

Yes that is the plan. Will get a load more CAT 6 by the sounds of it, its a 70mm duct so can get loads down it and there will be plenty of room for later projects. I will put 4 CAT 6 in. It was only the neutral and alarm I needed to send down to the house smoke alarms so the house alarms go off with the garden room ones and vice versa. I was using the millstone manor firex model where one common wire connects all the alarms so they go off together and there is (can be) a relay that interfaces to the house alarm wanted to KISS. Although you can double pole isolate the power to the garden room or the house which would mean that the smoke alarms in one place could be live from the other - might need rethink of that! So: (thanks all) 4 x CAT 6 1 x 6 core alarm cable. 1 x 3 core smoke alarm signal. (Assuming safe operation can be achieved) 1 x Draw rope (was going to be one anyway @Ferdinand.)

Ah ah - too many assumptions on my part sorry, will try harder to banish them from my thinking and expand my thought experiments to ensure all possibilities are covered.

Just getting ready to pull the cables through the comms duct to the garden room from the utilities center. (45m run ) Will be a model for the main house. So far I have: 2 x CAT 6. ( 1 for the home network and one for control systems network - somewhat experimental.) 1 x 6 core phone cable. Not absolutely required but will allow me to run a phone line down there separate from the house line. 1 x 3 core flexible to carry the smoke alarm signals from the garden room smoke alarms - not sure how to organise this electrically but 3 cores should be enough even if volt free contact. 1 x 6 core alarm cable for the intruder alarm. I wonder if I should also pull in a 4 core fibre? What have I forgotten?

Very smart you two - looks great.... any date for moving in pencilled in?

Are you out of the little brown bungalow... gone anywhere nice?

I guess it's one of those ask 10 economists and get 11 answers sort of a question. How is the other DHW provided?

Perhaps it is an example of recursion - for recursion see recursion...

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.

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?

I am sure I saw copper to plastic mentioned in the John Guest patent literature somewhere many years ago. I used plastic to copper several times for the build back at millstone manor, 10 years not a drip anywhere - well when I left this morning that is.

I am sure I read somewhere what a whacker will compact in type 1 depth, much less than 250mm, you probably need a roller for that. Here is a link http://www.broxbourneplant.co.uk/html/wacker_plates.html tells you depends on soil type but 300mm for the bigger one.

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!

I don't have a label printer but I could get one, any recommendations?

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.

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.

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. I think I will use flexible conduit as the two units are back to back through a 100mm block wall.

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?