# 2.5mm High-Tuff Cable - Circuit Protection

Discussion in 'Electrics UK' started by CAWORK, 22 Oct 2019.

1. ### CAWORK

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Good Afternoon,

I wish to install an outdoor twin socket on the outside wall of my parents stone cottage. I have considered using Hi-Tuff cable (grey in colour if possibly available) as I consider this to be the neatest looking solution.

My intention is to spur off a nearby indoor socket, which is part of the RF circuit and run the cable through a hole drilled in the bottom corner of the window frame and have cable clipped direct inside and out (inside socket is in store room at back of house so looks are not too important- would be absolutely impossible to drill straight through the wall).

However my main question is regarding the circuit protection/current rating of the 2.5mm Hi-Tuff cable, since it is of a flexible construction (rather than a solid 2.5mm T&E) is it satisfactory to be protected by a 32 amp protective device?

I understand a single 2.5mm spur from a RFC is satisfactorily protected (according to a previous issue of 'Switched On' magazine from overload, short circuit and earth fault protection although you need to be a mathematician to understand the calculations explaining why this is so).

Also where can I buy Hi-Tuff cable from? screwfix and Toolstation fairly near me do not appear to sell it.

NB
RFC in house protected by 30mA RCD.

Many Thanks

3. ### EFLImpudence

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Not for overload, it isn't, but for fault protection, yes - if the circuit is not too long.
The overload protection is by the two 13A fuses in the plugs.
2.5mm² flexible cable is rated at 25A; twin & earth 27A - so I wouldn't worry about the 1A.

As above.
There is a rather complicated equation to determine if the CPC(earth wire) is large enough although this would not apply to flexible cable as the CPC is the same size as the others (unlike twin and earth).
All you have to worry about is the 25A which is unlikely to occur.

Hi-tuf is rather difficult to work with - any flex will do - black is better for outside but it's up to you. White might not last as long but still years.

Good.

• Thanks x 1
4. ### EFLImpudence

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You could, of course, use 4mm² flex which is rated at 32A and not have to worry about anything but it is not necessary for one double socket.

5. ### Risteard

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Hi-Tuff is always black sheathed. NYM-J is grey but isn't UV tolerant (nor is it BS compliant but is a VDE product).

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8. ### aptsys

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Looks OK to me

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9. ### Risteard

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It's not suitable for external use (unless in conduit etc.)

Trust me - it's a commonly used cable in the south of Ireland.

10. ### markyd1

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And still no mention of a minor works cert for addition

11. ### DIYnot Local

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