I need some advice on a Zs issue!!!

[studentspark]

Ran a lighting circuit, singles in conduit, this circuit has a decent Zs 0.7ohms

Owner then decided to put in another light which he wanted switching separately.

I ran in a new switch live and neutral, no earth as I was using the earth already in the conduit.

Now this circuit gives me a Zs of 2.3mohms, which is massive.

The earth is continuous and r1 + r2 is good

Any ideas

 

[1john]

Bad connection somewhere unless a monster run, how far is the switch wire? what breaker is feedign the circuit?

 

[Adam_151]

If R1+R2 is good, but your loop is way out of what you expect... then perhaps there is an measurement issue with it... what range are you using on your loop tester, the non-trip ranges are often not that great... is there an RCD in the circuit?

 

[studentspark]

RCBO 10 A

Line and neutral to switch. This has a healthy Zs

Lighting circuit connected to supply health Zs

CPC continuous


New run which uses same CPC which is continuous, as is R1, massive Zs


Switch live about 20 m

 

[Adam_151]

As a sanity check could you move the circuit onto an MCB and do a full-fat loop test?

 

[studentspark]

Turned out to be the dimmer switch

High resistance at the switch, new one for me

 

[Adam_151]

Dimmer switch?

Cant remember you saying it was a dimmer before? Dimmers should be bypassed for testing, otherwise you risk A) damaging it and B) weird readings