max ze

[Badger]

What is the max ze for a bsen61008 RCD

 

[Andy™]

max Ze is always the same for set earthing types.... (0.35, 0.8, 200)

if you mean Zs... that depends on rating of RCD

 

[Badger]

yes soz meant zs

its just the nic insoector asked me today, and ive found out for a 63 amp or 80 amp rcd he said it was 1667 ohms

 

[Andy™]

the 63, 80, 100 etc etc is the max current the RCD can safely handle. note that it doesnt mean it will trip on overload like an MCB.

the RCD will have a mA rating - this is what matters. for a 30mA RCD (or RCBO) the max Zs is 1667 ohm

 

[mikel]

They asked me a similar question and gave me the same answer.

It comes from that resistance gives you a max touch voltage not exceeding 50v. Tis in Big red book. But as usual thats in't van.

Sorry if I've not explained it very well too manyGuiness Drink and lack of sleep

 

[Andy™]

touch voltage needs to be less than 50

so to work out Zs, use R=V/I

V being 50 in all cases

so for 30mA RCD, R= 50/0.03 = 1667 ohm

for 100mA

R= 50/0.1 = 500 ohm