Can I use flex instead of cable in my house wiring?

It's not a simple no. It a maybe....It's not something I have given much thought as I would always wire up in "proper" cables.

Flex is a class 5 cable and has a higher resistance than the equivalent class 1 (solid) and class 2 (stranded) BS 6004 cables.

Hmmm...presumably that means that if you have a reel of 13 amp flex you wouldn't use it for a ring main but you might be O.K. for a lighting circuit.

Or perhaps even a spur (since apart from issues like burying it in a wall it would be remarkably similar to an extension lead).

Not that I am proposing to do this although I do have (for some unknown reason) two large drums of flex in the shed.

Cheers

Dave R

Probably something like that. As I have never considered using buried flex for other than supplying boilers, fans and outside lights ie all in situataions where the CCC is well below the maximum allowed then I really have not much info.

A spur from a socket would have to use a cable/flex rated at 20amps.

I don't like the "old" - I would be concerned about the state of the insulation, and I suspect that if a fire started traceable to the electrics the OP's insurance company might use that as an excuse to remove cover.

Rob

I have a reel of 2.5mm and a reel of 4mm 3-core flex, and they aren't very easy to use - 2.5mm and 4mm T&E are much easier.

I did think of using 2.5mm flex to spur from a socket outlet lost behind fitted furniture, to a new socket mounted on the furniture, but never got around to it.

I fully agree. Since it's been notified and is likely to be inspected ISTM the height of folly not to use proper material. Why set yourself up to fail?

BS 7540 has already been mentioned. This standard is a Guide to Use of Cables [up to 450/750 V]. The clincher is clause 4.4.5 of BS

"Flexible cables and cords should not be used as fixed wiring unless contained in an enclosure affording mechanical protection, with the following two exceptions:

a) final connection to fixed equipment where the cable type is ordinary duty or higher [i.e. H05 or higher, not H03];

b) fixed installations in temporary buildings where the cable type is heavy duty [H07]."

IOW any 'flex' used, other than for the stated exceptions, should be in a conduit or trunking system.