Testing Zs at Lighting switch's with no neutral

[DanBrown]

Could anyone just give me a bit of advice regarding a Zs test at a light switch, as the tester i have just baught is the ''Fluke 1653'' tester and it uses a 3 wire test earth, live, neutral to aquire the Zs.

Am i right in saying that you have to do it manually by shorting live / earth at C/U and do a ohms check then add this to your Ze test?.

Your thaughts would be appreciated, Thanks

 

[ian.settle1]

The neutral is to allow the meter to work. So why not connect the neutral to earth to allow meter to work?

 

[TonyM58]

Dan

connect line (used to be called phase) to earth bar at the cu (supply isolated obviuosly!)

and measure between line and cpc at the light switch on low resistance ohms. This is your (R1+R2) value, and when added to the Ze is your ZS. Its very unlikely this will be recorded on your schedule of test results, as the highest Zs value should be a the switched live conductor on the last light in the circuit.

If you measure Zs at the switch, you are (in theory) contravening the Electricity at Work Regulations

 

[DanBrown]

In response to your anwer ian.
What do you actually mean by saying put neutral to earth to make the tester work.
Thanks anyway

 

[EasyFox]

He means put the meters blue & green leads to the cpc at the light switch.
But why do the Zs at a switch?

 

[TonyM58]

I agree with Easyfox

i would just confirm R2 at the light switch, and do my Zs at the ceiling rose (calaculated from the (R1+R2) value

Dan, i use a Megger. If we are on 'no trip loop' we use three leads, and normal earth fault loop is two leads (which connect to line and cpc). Cant recall how the Fluke carries out the Zs or Ze test, but do you have a two or three lead option? it wont be called 'no trip loop' but somenthing similar

 

[DanBrown]

Hi Guys,
Thanks for all your responses, The only reason i asked about testing at a light switch is to double check and make sure that the maximum Zs i recorded was actually the maximum Zs, seem s a bit stupid on my behalf but im kinda new to testing my work off. I am aware that with the theory and the actual Zs should be at the furthest part of the circuit as this has the highest resistance reading. Just wanted to 100% check and make sure my reading's were correct.

In response to you previous question tony, the tester uses 3 wire only, and it has ''non trip'', when you dis-connect the neutral lead from the tester it says ''lead''. You must be right in saying put neutral + earth leads onto earth terminal and live to live. I'll give it a try....

Thanks Guys

 

[alan]

All the leads in rotary sw to Z Tester should be on L-PE

At light put green crock to earth, blue to neutral and then red to phase.

 

[TonyM58]

Alan,

but that was his original problem, he's at a light switch so doesnt have a neutral!!!!

 

[alan]

He tests at the light fitting, if there no neutral there ,patient the idea

 

[Martin]

For loop testing with the Fluke, choosing L-PE will do a low current "no trip" 3 wire test. Choosing L-P will do a high current 2 wire test. For this connect the L probe to live and N to earth. Remember that the 2 wire test will trip any RCDs.

 

[TonyM58]

so the Fluke IS the same as the Megger

thought it would be

also think that two lead test will be virtually redundant under the 17th, all except PFC's at the CU

 

[alex]

The neutral is to allow the meter to work. So why not connect the neutral to earth to allow meter to work?

couldnt agree more.

 

[Malcg]

Hi
R1+R2 is only available at light drop / ceiling rose (also much easier to do).

Switch off main switch. Temp short MCB live to earth. at furthest rose, test using two leads (as L & E available).

Record result and remove temp link.

As shown on page 217/218 NICEIC Inspection, Testing, Certification and Reporting.

Hi

Also if you want to include switch drop, still test at ceiling rose with light switch on. Use Switch live, Neutral and earth. Then you get longest path of Live.

 

[Shakey]

Hi
R1+R2 is only available at light drop / ceiling rose (also much easier to do).

Switch off main switch. Temp short MCB live to earth. at furthest rose, test using two or three leads (as L, N & E available).

Record result and remove temp link.

As shown on page 217/218 NICEIC Inspection, Testing, Certification and Reporting.

Hi

Also if you want to include switch drop, still test at ceiling rose with light switch on. Use Switch live, Neutral and earth. Then you get longest path of Live.

Malc,

how/why would you use three leads to test R1+R2