low insulation resistance on 35mm lsoh cable

[markmca_no1]

Looking for some advice.currently doing a install of a block of flats fed from a bemco using 35mm aluminium split concentric cable low smoke.tested the cables and getin low readings of around 40 mega ohms on all between neutral and earth.1 cable is only 3 metres long.any one ideas why there
so low

 

[telectrix]

maybe a bit of damp. leave the IR tester connected for a minute, see if the reading increases.

 

[markmca_no1]

maybe a bit of damp. leave the IR tester connected for a minute, see if the reading increases.

Done that it did increase slowly.cut a few metres off the drum I used and meggered neutral and earth and only got 2 mega ohms

 

[Darkwood]

Has the end of the cable been left in water for a length of time like a puddle in storage? ... its possible if your meter is to be believed and the batteries aren't low and its calibrated regular that its drawn the water in through capillary action, the extent of this depends on the make up of the cable.