A question regarding insulation resistance. Please Help!

[nazoom]

Q. Explain by example , the effect on insualtion resistance and test results of

a) Cables connected in parallel?

a)Answer:
l Don't know

b) Variation in cable length?

Answer:
b) The longer the cable length the lower the insulation value.

Could you please answer these questions or tell me where I can find the answers to it?

Any help is much appreciated.

 

[IQ Electrical]

A) When cables are connected in parallel (as in a 'global' IR test on a DB), insulation resistance decreases.

Formula is 1/rtotal= 1/r1 + 1/r2 + 1/r3 etc etc.

B) The longer the cable length, the lower the insulation resistance value.