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Apprentice - Questions - Gas CU, Corner, Light SW in toilet?

Discussion in 'Electrics UK' started by Tobias1, 28 Mar 2014.

  1. Tobias1

    Tobias1

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    Hi Everyone,
    My boss has set me a few questions to discuss options on and I was thinking this forum looks like a good place to do that as based on some of the already asked questions. He recently has rewired a bungalow and came across these items and he has set me questions to see how I think.

    I will state my thoughts against the question and if people can challenge the answers that will help me view things in a different light (joke not intended).

    Q1 - You find in the airing cupboard a socket with a plug (3A fused) that feeds a Gas CH CU on the outer wall in the hallway. Do you put another socket in and leave rest alone, or change it?
    My thoughts A1 - I was thinking as a full rewire would be in process to then fit it to an existing circuit via a switched fused outlet. The Gas CU could then be isolated by switching off and if needing maintenance then to unscrew fuse cover located within the cupboard.

    Q2 - You have fitted a double socket to a interior wall (say East wall) for TV. The customer also requested another to fitted on the other interior wall (say North wall) which is at 90 degrees to each. How would you run the cables to stay within guidelines to keep both in circuit. Would you run Vert to loft from each socket looping to each or would you have one cable from loft to first socket then go to corner Horiz back out of corner then back to loft from the other socket? Either way it would be Horiz or Vert cabling.
    My Thoughts A2 - I thought it would be better to run cables both to loft rather than into corner. I cant see an issue with either, except by putting round a bend if in plastic conduit it would be tricky as you would need to negotiate a bend and if cable only into wall then the bend would be too sharp.

    Q3 - In the entrance hall there is a toilet room with a sink. The customer has asked for the switch to be inside the room rather than in the entrance hall. Do you fit a switch as it is in reach of sink, or insist on putting outside the w/c room, or fit a pull switch?
    My thoughts A3 - I thought fitting a switch in a small toilet room would not be an issue provided it is on an RCD or MCBO and any metal exposed fittings are bonded correctly. If it was with a bathroom or shower room then due to humidity and more risk of splashing then it would not be able to be done.

    Right guys - Slate my thoughts. I have only been doing the job now for a couple of months, but my boss wants me to start thinking installs through.
    Am I thinking right, or just being an idiot completely?

    Looking forward to your replies (I think - saying with caution)
    Tobias
     
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  3. Taylortwocities

    Taylortwocities

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    I don't understand the question. You say "another socket" is this additional?
    If not then the arrangement could stay as it is. The central heating system needs a double pole means of isolation and the plug will give you that (a plug&socket is an acceptable method of isolation accoprding to BS7671). Personally, I would change the boiler isolation to an FCU, but thats my personal preference.

    Its always best to run cables vertically up (plumbers don't expect cables to go horizontally). Sometimes its not practical as you may not have access to the ceiling space above. So you can go horizontally provided the cable run is in the accepted zones (see the WIKI). http://www.diynot.com/wiki/Electrics:walls

    The room is not a special location, it is the same as any other room. You can put whatever you like in there, sockets, switches. There's no need to bond anything in there. Requirement for RCD will only be needed to provide protection for cables concealed and less than 50mm from the surface (NOT because there's a sink in there!)
     
  4. EFLImpudence

    EFLImpudence

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  5. ericmark

    ericmark

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    When I was fitting alarms to BT buildings the first couple of hours would be spent working out my routes. What thickness the walls were, how many dog legs in conduit and as a result how many pull points for the cables was a major consideration and with careful planning the job was done quicker.
    On the odd time we would walk into a building which was a clone of one done before and as a result we could in the main copy the other building.
    With a house they are so similar we do tend not to plan as much as we should and jump in doing standard things without giving much consideration as to special needs. For example sockets for a TV. Where the coax runs down the wall having the mains horizontal could reduce interference also of course we tend to look at the BS7671 and forget about other regulations. Do study Part M we all know the 400mm or 450mm (domestic) limit and 1200mm limit but we forget about the 350mm limit for corners. Having light pull switch weights line up horizontally with door handles is another we tend to forget. So where the door handle is not at a standard height this can mean the pull cord length also becomes odd and gets tangled with people entering and leaving rooms. There should be at least 300mm of wall from door to corner which is plenty of room for a switch.
     
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  7. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    If it's a rewire, I would have the heating on it's own circuit protected by an RCBO.
    Shortest route.
    No shower, no bath, do as client as requested. There is no requirement for it to be on an RCD, but to omit RCD protection, then the cable would require if buried within wall to be mechanically protected or buried greater than 50mm (note Part A of building regs for chase depths)
    We all start somewhere, there are many publication available that offer guidance to the requirements, it is okay asking the question here, but you need to understand the reasoning behind them, the more work you do, the more head scratching you will also do. Just remember, generally there is more than one way one to skin the cat!
     
  8. sparkwright

    sparkwright

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  9. Tobias1

    Tobias1

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    Thanks for all the interesting responses. All the regs are a lot to learn, especially when you first start out. Do you guys know it off by heart or have to refer to it when needed.
     
  10. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    There is too much information to be able to know it all of by heart, but the common things, such as what you have asked about should be logged into the head.
    As you see by the varied answers you have been given, that there are number of was to meet compliances. When routing circuits I would always choose to go the shortest route, if it where practicable and compliant with the safe zones. This would cut down on chasing, material costs and keep down the r1+r2 of the circuit.
    Cloak rooms without shower/bath, I would personally have the switch in the room, rather than have some annoying git turning the light out from reverse wall while I was doing my business! And generally prefer the wall switch over pull cord. I would advice the client on my preferred options but if they prefer another method that complies I would be happy to follow their instruction.
    When it comes to central heating and hot water systems, if it is a rewire I would advise/recommend that this was a circuit unattached to any other circuit that has RCD protection on it, the reasoning behind this would be if a RCCB did trip due to a fault unrelated to the heating system, then you have lost HW/CH, untill that fault has been found and repaired. If it just so happened that the RCCB tripped whilst on holiday during a cold snap, there would be a possibility of pipes freezing and bursting as the house would not get warmed nor would central heating pipes, so for me it would be either a circuit that excludes RCD protection (in compliance to BS7671) or a RCBO dedicated circuit.
     
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