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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Armour cable
Hi
I need to wire in my garden electrics with armour cable etc... Can anyone advise on what MCB's and what size armour cable to use? I have done a small diagram if it helps? http://i5.tinypic.com/20iz8jn.gif many thanks |
#2
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Armour cable
"John" wrote in message
... Hi I need to wire in my garden electrics with armour cable etc... Can anyone advise on what MCB's and what size armour cable to use? I have done a small diagram if it helps? http://i5.tinypic.com/20iz8jn.gif many thanks You need to tell us the cable lengths before an accurate answer can be told :-) |
#3
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Armour cable
"Sparks" wrote in message ... "John" wrote in message ... Hi I need to wire in my garden electrics with armour cable etc... Can anyone advise on what MCB's and what size armour cable to use? I have done a small diagram if it helps? http://i5.tinypic.com/20iz8jn.gif many thanks You need to tell us the cable lengths before an accurate answer can be told :-) House to Garage = 8m Garage to Shed = 6m Shed to Summerhouse = 5m cheers ;-) |
#4
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Armour cable
House to Garage = 8m
Garage to Shed = 6m Shed to Summerhouse = 5m There are lots of ways you could do this. I'd run 6mm 2 core SWA from the house to the garage, with a 32A Type B MCB in the house. At the garage, I'd have: 30mA RCD for the entire lot. Isolate the earth from the house. Do not connect to the garage. Use an earth rod. 6A MCB for the lighting 16/20A MCB for the sockets (you can go up to 32A if you wish) 16A MCB for the shed/summer house Then 3 core 2.5mm SWA, exporting the garage earth down one core, from there to the shed and summer house. Run shed/summer house lighting from local 3A FCUs if the fittings do not indicate compatibility with a 16A circuit. Don't forget that you will need to notify the council and have the installation tested. Note that your proposed spotlights for your garage might not be a good idea. Spotlights are appalling inefficient for space lighting and contribute significantly to global warming. Christian. |
#5
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Armour cable
"Christian McArdle" wrote in message ... House to Garage = 8m Garage to Shed = 6m Shed to Summerhouse = 5m There are lots of ways you could do this. I'd run 6mm 2 core SWA from the house to the garage, with a 32A Type B MCB in the house. At the garage, I'd have: 30mA RCD for the entire lot. Isolate the earth from the house. Do not connect to the garage. Use an earth rod. 6A MCB for the lighting 16/20A MCB for the sockets (you can go up to 32A if you wish) 16A MCB for the shed/summer house Then 3 core 2.5mm SWA, exporting the garage earth down one core, from there to the shed and summer house. Run shed/summer house lighting from local 3A FCUs if the fittings do not indicate compatibility with a 16A circuit. Don't forget that you will need to notify the council and have the installation tested. Note that your proposed spotlights for your garage might not be a good idea. Spotlights are appalling inefficient for space lighting and contribute significantly to global warming. Christian. Nice one Christian cheers |
#6
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Armour cable
Christian McArdle wrote:
House to Garage = 8m Garage to Shed = 6m Shed to Summerhouse = 5m There are lots of ways you could do this. I'd run 6mm 2 core SWA from the house to the garage, with a 32A Type B MCB in the house. At the garage, I'd have: 30mA RCD for the entire lot. Isolate the earth from the house. Do not connect to the garage. Use an earth rod. 6A MCB for the lighting 16/20A MCB for the sockets (you can go up to 32A if you wish) 16A MCB for the shed/summer house Then 3 core 2.5mm SWA, exporting the garage earth down one core, from there to the shed and summer house. Run shed/summer house lighting from local 3A FCUs if the fittings do not indicate compatibility with a 16A circuit. Don't forget that you will need to notify the council and have the installation tested. Note that your proposed spotlights for your garage might not be a good idea. Spotlights are appalling inefficient for space lighting and contribute significantly to global warming. Christian. Why the earth rod for shed? would you like to quote a reg to justify it please. My preferred way would be 5 way consumer unit in garage rcd sockets where nessary, no rcd protection to server (to prevent nusicence tripping) agree with all mcb/cable sizes but would put small 2way "garage consumer units" with rcd main switch in shed and summer house |
#7
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Armour cable
mitchd wrote:
Why the earth rod for shed? would you like to quote a reg to justify it please. My preferred way would be 5 way consumer unit in garage rcd sockets where nessary, no rcd protection to server (to prevent nusicence tripping) agree with all mcb/cable sizes but would put small 2way "garage consumer units" with rcd main switch in shed and summer house Not an engineer etc... I doubt there is a specific reg that says "you must do TT etc". It's going to be a matter of making the design compliant with several relevant regs. If you are going to export the house earth then it must be safe to do so. See here first for some excellent background info: http://www.iee.org/Publish/WireRegs/...s_answered.pdf If you have a TN-S (elec co supply earth as a separate core back to substation) then many would agree that exporting to outbuildings is OK over short distances, for some definition of short that I'm not prepared to define... PME supplies are dodgey as it's not impossible for the earth/neutral to fall off upstream (esp. in rural locations) then your neutral AND your local earth is now being pulled up towards phase by attached loads (yours or neighbours'). In the case of a metal greenhouse with supply and earth bonding, your frame is now at 240V and the ground is still earthed - so you get the idea. And you don't bank entirely on the main RCD to get you out of trouble... TT - you have your own electrode with a relatively high impedance. Phase to earth fault in the house will float this up (and thus your greenhouse frame in the previous example) to potentially dangerous voltages relative to the real earth. Wet grass, bare feet leaning on the greenhouse you would not need full mains voltages to potentially kill you. -- If you have doubts as to exporting the supply earth, then the only sensible option left is a local TT earth at each location (shed/greenhouse/garage etc). This must be a proper TT installation, required RCD and MUST be tested to prove that it has suffiently low impedance. Potential for messing it up exists, so the testing is exceedingly important (Whifield's exposition on the wiring regs does detail a method involving multimeters and a car battery, but may as well hire a suitable tester). With the greenhouse example, a phase-earth fault in the house has no effect providing you isolate the two earthing systems, and a local fault is hopefully going to achieve a lower differential voltage betwen the ground and the frame (because the earth rod is in the vincinity). It's deemed acceptable because there's not a lot else you could do to better it. The whole thing is a bit of a minefield and it's far less easy to just give a prescription answer, compared to many other aspects of domestic wiring. All of the above is an attempt to offer general explanation to your query, do not take it as a recipe to implement a specific solution!!! Cheers Tim |
#8
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Armour cable
mitchd wrote:
Why the earth rod for shed? would you like to quote a reg to justify it please. I suggest the following are relevant: 130-02-02 131-01-01 (i) 541-01-01 541-01-02 542-01-09 -- Andy |
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