Suitable cable to make extension lead

Risteard

zax47 wrote: »

(just 4.1% which is below the allowable 5%)

The 5% for power and 3% lighting is not actually a Regulation, but is stated in an Informative Appendix to BS7671. Proper functioning must be ensured by Regulation.

That said, 4.1% on an extension lead completely ignores the voltage drop on distribution circuits and final circuits, which may already have seen a couple of percent or more.

(yes, it will just fit in a "normal" BS1363 13A plug, but I'd use proper commando connectors & make up a small patch cable to a "normal" plug.)

Regardless of whether it fits the plug or not (which generally it won't) it is not permitted to wire a BS1363 plug with 2.5mm^2 flex. It directly contravenes BS1363.

Scrounger

Risteard wrote: »

Regardless of whether it fits the plug or not (which generally it won't) it is not permitted to wire a BS1363 plug with 2.5mm^2 flex. It directly contravenes BS1363.

Sometimes the law is an A$$$ :rotfl:

[So long as the 2.5mm cable will fit and can be clamped in the cable grip there is no danger and (unlike the 16A Commando Plug) contains an integral cartridge fuse for additional safety.]

Scrounger

Risteard

Scrounger wrote: »

Sometimes the law is an A$$$ :rotfl:

[So long as the 2.5mm cable will fit and can be clamped in the cable grip there is no danger and (unlike the 16A Commando Plug) contains an integral cartridge fuse for additional safety.]

Scrounger

Nonsense to say that "there is no danger".

2.5mm^2 does not properly fit a BS1363 plug and must not be used with one.

Also, a cartridge fuse does not provide additional safety where a 2.5mm^2 flex is used as this is already protected by the 16A / 20A protective device. The purpose of the fuse is simply to protect the cable and not for any other purpose.

Scrounger

Risteard wrote: »

2.5mm^2 does not properly fit a BS1363 plug ...

Depends on the design of the plug and the skill of the fitter.

Perhaps we have discovered a requirement a special 'high-spec' 13A plug designed for thicker cables (for long runs, thicker jackets, armoured mains cables etc) ?

Risteard wrote: »

Also, a cartridge fuse does not provide additional safety where a 2.5mm^2 flex is used as this is already protected by the 16A / 20A protective device.

Is it, where is that mentioned in the above discussion?

For all we know the supply in this case could be straight from a CU 32A breaker (or fuse wire).

Even if it is fed from a CU breaker, IMO it is much better to have an additional local 13A (or less) fuse in the circuit (in addition to the CU breaker or fuse which could be much larger capacity). Belt and braces.

Risteard wrote: »

The purpose of the fuse is simply to protect the cable and not for any other purpose.

Sorry, I thought we were discussing cables here. Are you reading from a textbook ?

Scrounger

Risteard

Scrounger wrote: »

For all we know the supply in this case could be straight from a CU 32A breaker (or fuse wire).

A 16A BS EN 60309 Commando can be supplied by a 16A or 20A device, not a 32A device. Therefore the cable is protected.

Therefore a BS 1362 fuse has no purpose here.

Risteard

Scrounger wrote: »

Perhaps we have discovered a requirement a special 'high-spec' 13A plug designed for thicker cables (for long runs, thicker jackets, armoured mains cables etc) ?

There is no requirement as none of these things are appropriate for a BS 1363 plug. There are other - better and correct - options which can be used if any of these things are necessary.

A 2.5mm^2 cable connected to a BS 1363 plug is NEVER compliant with the Standard.

Owain_Moneysaver

The instantaneous starting current of the motor may be a lot more than the nominal 3 kW rating of the motor, which will affect the voltage drop calculations.

I agree with Zax47; the practical approach is to make up a 2.5mm 25 metre extension lead using 16 A 'Commando' connectors with adapter leads at each end - although if it's for this application only I'd change the plug on the appliance to 16 A, and fit a 16 A 'coupler' flying socket on the extension lead, so only need a 13 A - 16 A adapter lead at the supply end.

Rotor

Hi, well I got hold of a multimeterand checked the voltage. At the house it is 243v (although it was 236v sunday after dark when i guess lots of people were using electricity) and also 243v in the barn. This was a no load reading- do I need to have a powerful appliance running to get a true idea of how the voltage drops?

Rubidium

Rotor wrote: »

Hi, well I got hold of a multimeterand checked the voltage. At the house it is 243v (although it was 236v sunday after dark when i guess lots of people were using electricity) and also 243v in the barn. This was a no load reading- do I need to have a powerful appliance running to get a true idea of how the voltage drops?

You are over thinking this.

Just buy a reel of 1.5mm T&E and get splitting them logs!

The induction motor will run fine down to 220V and probably much lower with no problems. It will likely have thermal overload built in for self protection.