A few questions

[lee1002]

hi im doing my 2391 in a couple of weeks and i have just been going through a few past papers i have. Im just a little unsure about these questions and wondered if anyone could help me.

1) state why the test for continuity of protective conductors must be conducted before:
a)insulation resistance
b)polarity
c)earth fault loop impedance
I know that it will be needed to be done to show there is an earth fault path but unsure on the rest.

2)state
a)the two ip codes relating to penetration tests on enclosures that have had insulation applied on site.
b) which other tests should be applied to a)

thanks.

 

[Des 56]

An insulation test could be carried out at the extremity of a circuit where the cpc is not continuous
You would then be insulation testing live/neutral to nothing

You need cpc continuity confirmed, before the result of an insulation test can be asured for that reason

 

[lee1002]

thanks mate.

 

[pushrod]

hi im doing my 2391 in a couple of weeks and i have just been going through a few past papers i have. Im just a little unsure about these questions and wondered if anyone could help me.

2)state
a)the two ip codes relating to penetration tests on enclosures that have had insulation applied on site.
b) which other tests should be applied to a)

thanks.

Not certain but is this to do with horizontal up facing surface on CU which must be IPX4 (use blind grommets and push canbles through) and all othe surfaces needing to to be IPX2 (use open grommets)

It is to stop the risk of falling strands of wire entering the CU. Not sure what it is getting at with part b) so i could be wrong.

With the continuity - insulation resistance test (in addition to what Des said) you need to ensure that your IR test is over the whole length of all conductors
. If you hadn't already proved continuity you wouldn't know this.

 

[lee1002]

im not sure about part b either m8 i have just bought the gn3 so going to have alook through it and see what it says in there. thanks for your help