PAT - flexible cables

[Dave Plowman (News)]

I've Googled without success. Anyone give a rough guide as to the maximum lengths of common flexes that would pass PAT?

[Andy Wade]

I'm assuming you don't mean for extension leads, for which Andrew Gabriel has often posted the figures.

For attached appliance cords or detachable cord sets the official Code of Practice says the following:

15.13 Replacement of appliance flexes

The maximum lengths recommended for extension leads are not applicable to appliance flexes or cord sets.

For flexes to be protected by the fuse in a BS 1363 plug there is no limit to their length, providing that their CSAs are as below:

Fuse rating Min. CSA ----------- -------- 3 A 0.5 mm^2 13 A 1.25 mm^2

Other considerations such as voltage drop may limit flex lengths. Smaller CSAs than those given above are acceptable if flex lengths are restricted. However for replacement purposes the above simplified guidance is appropriate.

[Cicero]

======================= A very rough guide can be derived from the length of cable fitted to some new appliances. One of my routers (woodworking -not computing) has a very flexible 5 metre cable. If it's OK for manufacturers it's probably OK for the rest of us.

Of course it's probably safer to use shorter cables for the more 'domestic' type of appliances such as kettles etc.

Cic.

[John McLean]

Maximum lengths of extension leads are provided in IEE CoP for In-Service Inspection & Testing of Electrical Equipment.

1.25 sq mm - 12m 1.5 sq mm - 15 m 2.5 sq mm - 25m

Above this, the CoP says an RCD is required.

Other than that, the only length requirement I know of specifically in a non-appliance standard is Table 2 of BS1363-1, which states that if an 0.75 sq mm flex is used for an appliance rated at 10 A, it must be 2 m or less.

I'd stick to a length that allows the appliance to be moved (if required), but where possible the flex is kept short enough to avoid mechanical damage to it.

Jaymack

[Cicero]

======================= I've just thought of my new lawn mower. It has a 20 metre cable but it's not as flexible as my router cable. In practice, flexibility may be more important than maximum possible length.

Cic.