Allowable resistance to ground 1

[dhfrye]

We have two submergable heaters in a concrete cooling tower sump. They are about 7 months old. Our MCC showed a ground fault and investigation show the heater to have 0.33 ohms to ground which is not very much. Is this acceptable? I didn't think any thing but zero would be but can't find a reference.

 

[rbulsara]

Heater element to ground should be in few megaohms. 0.33ohms is effectively a short to the ground and hence the ground fault. Replace the heater..