PAT testing 32A cable

jamagi · Apr 30, 2020

We have some 32A extension leads that range from 5m to 20m, I'm struggling to find what the acceptable values are for the resistence test. The PAT tester has a built in calculator, but that only goes up to 4mm cable, this is using 6mm. Where can I find the information I need to get the pass values to create my own test? Thanks.

westward10 · Apr 30, 2020

This is from Code of Practice for In-service Inspection and Testing of Electrical Equipment. The list only goes from 1.25 to 2.5mm however one thing remains constant regardless of size and that is resistance, a quick calculation has them all at approx 0.18 ohm.
Length increases with csa and from this list this is approx ×10 of the csa so you could say for 6mm you have 60m to play with which also calculates to 0.18ohm.
Unable to load file but this is from the CoP
1.25mm -12m
1.5mm - 15m
2.5mm - 25m

Pete999 · Apr 30, 2020

jamagi said:
We have some 32A extension leads that range from 5m to 20m, I'm struggling to find what the acceptable values are for the resistence test. The PAT tester has a built in calculator, but that only goes up to 4mm cable, this is using 6mm. Where can I find the information I need to get the pass values to create my own test? Thanks.

Get a copy of the ISITEE (PAT) CoP all the info will be in this publication.

telectrix · Apr 30, 2020

resistance of 6mm @ 20deg.C. is 3.08 milliohms/meter. so you can workout the resistance of, say, 20m. i.e. 3.08 x 20 = 0.062 ohms. (to 3 dec. places).

telectrix · Apr 30, 2020

Table 5.5 - Resistance per metre of copper conductors at 20°C for ---------------- calculation of R1 + R2
Conductor cross-sectional area (mm²)	Resistance per metre run (m ohms / m)
1.0	18.1
1.5	12.10
2.5	7.41
4.0	4.61
6.0	3.08
10.0	1.83
16.0	1.15
25.0	0.727
Note that to allow for the increase in resistance with increased temperature under fault conditions the values of {Table 5.5} must be multiplied by 1.2 for p.v.c. insulated cables (see {Table 8.7})