TPN Isolator testing

[The apprentice]

Hi there thanks in advance for the help iam still learning but soon to sit my trade test, on the booth picture number four is a TPN isolator I have to chose the correct fuses but on the testing this piece of equipment R1 R2 3 phases to earth record highest reading at end point I don’t need to disconnect my fuses due to higher resistance do I ? From fuse wire in the 88-2 type G fuses with max Zs of 4.0 ohms thanks in advance

 

[The apprentice]

Hi there thanks in advance for the help iam still learning but soon to sit my trade test, on the booth picture number four is a TPN isolator I have to chose the correct fuses but on the testing this piece of equipment R1 R2 3 phases to earth record highest reading at end point I don’t need to disconnect my fuses due to higher resistance do I ? From fuse wire in the 88-2 type G fuses with max Zs of 4.0 ohms thanks in advance

Also when noting down on the test paper do I knife down the breaker or the fuses for on the testing papers ?

 

[littlespark]

R1 R2 is a dead test…. You’re testing from the outgoing side of the fuses.
The idea is to test only the cables… nothing else.

Testing through the fuse will give false readings.

 

[The apprentice]

R1 R2 is a dead test…. You’re testing from the outgoing side of the fuses.
The idea is to test only the cables… nothing else.

Testing through the fuse will give false readings.

So would you just link it out from the fuses to get a reading at the end point

 

[westward10]

The fuses do not need linking out as @littlespark said you test from the outgoing side of the fuses anything before them is a different aspect.

 

[The apprentice]

The fuses do not need linking out as @littlespark said you test from the outgoing side of the fuses anything before them is a different aspect.

Thanks again really appreciate your help type G fuses at 16 amps iam led to believe as for putting down on the test papers the 3 phase breaker that feeds them will I be noting down the zs for fuses or the 3 phase breaker ?

 

[Lister1987]

will I be noting down the zs for fuses or the 3 phase breaker ?

Think about the circuit, draw it out, remembering there are distribution circuits and final circuits - Whst is the defining difference between a distribution circuit and a final circuit?

What do you think you were advised above to test from the outgoing side of the BS88 fuse?

 

[The apprentice]

Think about the circuit, draw it out, remembering there are distribution circuits and final circuits - Whst is the defining difference between a distribution circuit and a final circuit?

What do you think you were advised above to test from the outgoing side of the BS88 fuse?

Yeah I thought I’d be measuring the outgoing side of the fuses which would be fed via a 3 phase mcb but then iam thinking as in if I test outgoing I would get a higher resistance through the fuses so I thought I’d put down the fuse sizing and rating an in accordance the max zs value on the test sheet