Pat testing - low insulation reading

[tomodo]

Hi all, recently pat tested abit of equipment, it contains 24v power supplies, a frequency inverter, relays and a motor, its on a 13amp plug so requires pat test, however we get a low LN to E reading unless we disconnect the inverter. Reading is 0.9Mohms, is this normal or should you still requires the minimum 1Mohm resistance to earth. Thanks

 

[westward10]

Have you tried the test at 250v?

 

[tomodo]

We will do but doesnt it need to be a 500v test LN to E?

 

[westward10]

There are possible filters within it which are being triggered by the 500v.

 

[tomodo]

Tested at 250 but still low resistance 0.9

 

[westward10]

I think this would need the manufacturer's input either by you or the client.

 

[tomodo]

I have just spoke to them on the phone they dont seem so sure either :/ waiting on a message back. Surely it needs to be above the minimum 1Mohm to be satisfactory even just testing at 250v dc?

 

[westward10]

Does your tester perform an earth leakage test?

 

[James]

I have known some inverters to be damaged by insulation testing.
as a general rule, i tend to avoid doing an insulation resistance test on things like that, check plug and cable but disconnect from internal electronics.

 

[gaxxter]

Hi all, recently pat tested abit of equipment, it contains 24v power supplies, a frequency inverter, relays and a motor, its on a 13amp plug so requires pat test, however we get a low LN to E reading unless we disconnect the inverter. Reading is 0.9Mohms, is this normal or should you still requires the minimum 1Mohm resistance to earth. Thanks

what is the piece of equipment and part number?