Is it dangerous a low reading such as 1Kohm for IR I know you need to seriously investigate but if a 3 phase submersible pump is installed correctly wouldn’t the breakers/ fuses blow before the equipment is unsafe.
Exactly so, and if the earth wiring is solid (say less than one ohm,), then even though this is nearly quarter of an amp running off the wrong way, the case of the pump will not be significantly live, say 1/4 of a volt for those numbers ...
But now you only need one fault, rather than the usual two, to make things very dangerous - a single rusty bolt or a loose screw anywhere along that earth path might not normally be an issue, but now suddenly in that case the motor (or worse some of the building metalwork connected to it) is not as safe to touch as you thought.
Also be aware that many insulation meters are not very accurate doing readings well away from the 1 meg pass-fail limits where they are calibrated. Unless you have verified that 1k ohm with another meter that has a resistance range that is more suitable I should just mark it up as very low, and not be too surprised if your missing quarter of an amp was actually twice or half that on another instrument. In the meantime, double check the reading really is due to the motor, and not the controller or a joint in the wiring, then ring round to get a quote for a new one, you'll be needing it soon.
Exactly so, and if the earth wiring is solid (say less than one ohm,), then even though this is nearly quarter of an amp running off the wrong way, the case of the pump will not be significantly live, say 1/4 of a volt for those numbers ...
But now you only need one fault, rather than the usual two, to make things very dangerous - a single rusty bolt or a loose screw anywhere along that earth path might not normally be an issue, but now suddenly in that case the motor (or worse some of the building metalwork connected to it) is not as safe to touch as you thought.
Also be aware that many insulation meters are not very accurate doing readings well away from the 1 meg pass-fail limits where they are calibrated. Unless you have verified that 1k ohm with another meter that has a resistance range that is more suitable I should just mark it up as very low, and not be too surprised if your missing quarter of an amp was actually twice or half that on another instrument. In the meantime, double check the reading really is due to the motor, and not the controller or a joint in the wiring, then ring round to get a quote for a new one, you'll be needing it soon.
