Cable size identifi...
 

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Cable size identification

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Is there a way to tell the gauge of twin and earth.

I have an 80’s era armoured cable feeding an outside supply to green house/shed.
Multiple strands for all conductors so I assume greater than 2.5mm.
Electrician put a 32 amp rcbo on it when the consumer unit was replaced a few years ago.
I assume 4mm or 6mm but is there a way to tell?!


 
Posted : 09/05/2023 2:13 pm
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It might be embossed or printed down the side of the cable, look for the slightly raised print and it might say, eg 2x4mm, or 3x6mm


 
Posted : 09/05/2023 2:24 pm
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I'd disconnect the powered end and measure the core size with some vernier calipers....


 
Posted : 09/05/2023 2:42 pm
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You of course have the paperwork your elecrician left for you? The test results page should list cable sizes on each circuit. But otherwise size will be embossed on the sheath.
(Im always curious how diligent electricians are at completing and supplying the paperwork).


 
Posted : 09/05/2023 2:53 pm
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You of course have the paperwork your elecrician left for you? The test results page should list cable sizes on each circuit. But otherwise size will be embossed on the sheath.
(Im always curious how diligent electricians are at completing and supplying the paperwork).

potentially 40 year old paperwork ? - asside from the obvious of the paperwork being old - were you in your current house 40 years ago?

Footflaps is probably the most obvious solution.


 
Posted : 09/05/2023 3:10 pm
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Steveb I was going to give you the bingo card. But having looked at the paper work I think he’s filled it in wrong as it has 1mm conductor and 6amp fuse listed which I’m pretty sure can’t be right!


 
Posted : 09/05/2023 3:10 pm
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potentially 40 year old paperwork ?

There wouldn't have been any paper work 40 years ago, long before all the Part P nonsense was introduced.


 
Posted : 09/05/2023 3:19 pm
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To those saying what paperwork on 40 year old system....read the OP, new CU was recent, even if the shed cable is older.


 
Posted : 09/05/2023 5:11 pm
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This might help if you know how many cores you have, there's a nominal diameter top left in the product web page https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Armoured_SWA/index.html#2_Core_Armoured_SWA

Measuring won't be easy if it's squashed in one dimension and don't forget that it's mm2 and not a diameter, needless to say make sure that it's totally safe before going near a bare conductor


 
Posted : 09/05/2023 6:19 pm
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Is it twin and earth or armoured?
I’m presuming armoured as it is outside. All stranded cable means nothing, as SWA (armoured) cable always has stranded cable.
As ‘creakindoor’ says, there may be size markings on the cable, though not always.
If there are no markings, then you need to check the size at one of the terminations. 2.5mm and 4mm are sometimes difficult to distinguish between each other. A piece of known cable size helps.
If the electrician knew what he was doing, then it will be 4mm or 6mm, as 2.5mm will not be protected by the 32A RCBO.


 
Posted : 09/05/2023 6:57 pm
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It’s armoured but still looks like there are 3 conductors but perhaps there aren’t.

I should clarify I assume it’s a 32 amp fuse as it has B32 on it…


 
Posted : 09/05/2023 7:19 pm

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