On Mar 15, 1:42*pm, Fred wrote:
Anyway, some of my tools have started switching on and off
intermittently when plugged into the lead

If the cable is ok & 1.25mm^2 you could just replace the rest...
- Check the plug & strain relief are ok
- Remove any reel, they invite coiled use to avoid a trip hazard only
to overheat
- Fit a new duraplug or generic rubber 2-way or 4-way socket strip

If the cable is not ok...
- Buy or make up a short lead (10m) and long lead (20m)
- Do not go so short you need to daisychain leads, that invites other
problems

Cable sizing...
- For 13A load IEE guidelines are 1.5mm^2 to 15m, 2.5mm^2 to 25m.
- The aim is to prevent sufficient voltage drop that operation of
equipment at the end of the lead is impeded (motor does not start,
sits there cooking) or a short circuit does not permit sufficient
current flow to blow a fuse (cable sits there melting, cable becomes
the fuse)
- Real world is it depends on what you are going to stick on the end
of it.

Fridge-freezer.
- A long extension lead may cause sufficient voltage drop to prevent
the compressor starting, ruining food or creating a fire hazard.
- However, 25m of 2.5mm^2 flex from a CU is no different to 25m of
2.5mm^2 flat-twin-&-earth from a CU. (The CPC is actually larger in
the former, but not my point).

Tumble dryer.
- A 3kW load that melts solid extension leads not fully unwound, or
equally just dumped on the floor.

Pressure washer with beefy 1.7kW induction motor.
- Despite the spec, 25m on 1.5mm^2 is fine because it is only a 7A
load and the motor is not likely to stall.

Battery charger & light, soldering iron 50m away in shed.
- Gets more interesting when you add a 3kW fan heater or big induction
motor saw.
- Reality is the longer the cable, the more permanent its
installation, the greater the risk of damage occurring.

Never forget the RCD and test it. Avoid reels, they seem to induce
people to keep cable wound up to avoid a trip hazard yet can create an
overheating risk. Not all extension reels have thermal cutouts and
quality of stuff these days is a bit hit n miss. Warranty claim after
the carpet has a reel shaped burn in it is not going to go down
well :-)