another Zs question

[madeinengland]

hi guys. am doing my 2392 at the mo and am a bit confused.

for the Zs test does all bonding and earthing need to be in place or do you disconnect the bonding for extraneous parts?

my tutor told me (and therfore in my notes i have) that you disconnect the bonding for the water and gas pipes as you will send a small current through this bonding and therefore could shock someone in a real life situation.

but i've just read in a book that in order to do the Zs test it says "ensure all earthing and bonding is in place"


so which is it?

 

[acat]

Ze remove main bonding Zs bonding in place MCB on rest of MCBs off.

Hope that clears it up for you.


Chris

 

[Guest123]

When Zs is measured it is done so under "normal service conditions" i.e all bonding connected.

Ze is measured with the main earthing conductor disconnected.

 

[madeinengland]

cool. thanks guys.

what about during IR test. we've been told to do the insulation resistence test between the earth block and nuetral block in the CCU to the tops of the breakers.

i'm sure the tutor said that water and gas pipe bonding has to be off for this test too. in 3 years of college this is the first time this has been said to me. is this correct?

 

[Guest123]

i'm sure the tutor said that water and gas pipe bonding has to be off for this test too. in 3 years of college this is the first time this has been said to me. is this correct?

You dont have to disconnect the bonding to do this test. However as it's a dead test it is safe to remove them so cant really say he's wrong, it's just a bit uneccessary.

If you do disconnect, then you have to remember to put them back too.