R1 and R2 parallel earth

[stv292]

hi guys and girls,
any ideas on why when cunducting an R1 and R2 and also polarity when it was a closed circuit i had 1.87 ohms but when opened circuit 238ohms. this was on a lighting circuit pme system all correctly main bonded and zs complied.
thanks

 

[johnboy6083]

First of all, did the IR tests show anything? It could be a crap switch, or the internals of the lights themselves.

 

[stv292]

Ir was good about 140Mohms the lights are class 1 fittings, pretty old and crap

 

[Richard Burns]

Was the main switch still on at the CU? If there were other lights in the circuit with their switches "on" then the measuring current can run from the CPC through the N-E connection up the neutral through the light bulb and back to your line conductor, then you are measuring the resistance of the light bulbs "on" in the circuit.

 

[stv292]

yes, it was just that circuit i was working on so just that circuit isolated. it was a tidy job before me, they looped the live out the com in a 2gang switch then used the earth as a switch live, then at the ceiling light connected the earth to a single and ran it to the wall light's. all earth's cut off on class 1 fittings. been like it years he said. been put right now.