2391 help!

[soulman]

Hi lads, need a bit of help for my 2391 a couple of questions i'm not a 100% sure of

1. how to test for seperation between a selv circuit and low voltage circuit in the same containment

2. can someone simplify a earth electode test with an earth electrode tester.

cheers lads

i'm sure i'll have more questions throughout the day.

 

[Zeespark]

1. Not 100% sure of without checking.

2. Ra testing - its in GN3.

AndyGuinness

 

[Sidewinder]

IIRC they are both in GN3, mine is in the van & I'm having my dinner.

I'll try to remember to check when I go out to the van later & post back.

 

[SLIPSHOD & SLAPDASH]

Good questions, both i rarely have a need to know . Does 2 have something to do with a black & white cow ?

(That's all i can remember from the book) oh and 3 electrodes.

 

[Sidewinder]

I forgot, your like reminded me!

In red GN3 see pg 41 for ELV separation testing.

Ra test pg 46 same book, no simplification, remember it verbatim along with all of the other tests required.

 

[johninlondon1]

This test requires the use of three electrodes: the earthing electrode under test, a current electrode and a potential electrode.

The earthing electrode (E) should be driven into the ground in the position that it is to be used. Make a note of the length of the

length of the electrode which is in the ground.

The current electrode (C2 spike) should be pushed into the ground at a distance of ten times the depth of the electrode under test away from it.

The potential electrode (P2) should be pushed into the ground midway between E and C2.

The leads of the test instrument should be connected to the appropriate electrodes.

Measure the value of resistance.

Move P2 back to 10% closer to E than the mid-point.

Measure the value of the resistance.

A calculation must now be carried out to find the percentage deviation of the

resistance values.Then work out the % deviation between the average value and the highest measured high vale. Work out the percentage of this value to the average value and this is the % deviation if this value when multiplied by 1.2 exceeds 5% then this test is not suitable and further tests need to be completed increasing the distance between electrodes.

 

[steptoe]

do you still need help with the Ra test?

my mate has just done a simple drawing of it for me to use,

BUT,

as SW says, you need to use the version accepted by 2391, so learn them off by heart,

oh, good luck.