Testing Zs at Lighting switch's with no neutral - Page 2 - Electricians Forum | Electrical Forum | An electrical forum for electricians in the UK

Martin · 05-02-2008

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.

05-02-2008

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 · 08-02-2008

Quote:

Originally Posted by ian.settle1

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 · 18-04-2008

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 · 19-04-2008

Quote:

Originally Posted by 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 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

Malcg · 05-05-2008

modified

ian.settle1 · 05-05-2008

Quote:

Originally Posted by Shakey

Malc,

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

Because some meters require L + N for meter to work

Shakey · 06-05-2008

Quote:

Originally Posted by ian.settle1

Because some meters require L + N for meter to work

Not testing R1+R2 they dont, you are talking about Zs surely?

ian.settle1 · 06-05-2008

Quote:

Originally Posted by Shakey

Not testing R1+R2 they dont, you are talking about Zs surely?

Depends if your using a Megger (can't remember the model) as when you take the Ze reading and record it in the meter then when you take Zs at end of circuit it will calculate the R1+R2 for you when downloaded into computer.

Shakey · 06-05-2008

hmmmm, dont really like that Ian

R1+R2 is a resistance reading (as you know)

i.e dead

Zs and Ze are impedence (live) (yes, egg sucking and all that

)

We know that Zs = Ze + (R1 +R2) but adding R1+R2 to Ze does not automatically give the the same result as Zs (for many reasons which I know I dont need to explain to you!)

so taking Ze from Zs will not give an accurate R1+R2 either

Personally I would never do this, as Zs is the least preferable of the readings (due to the EAWR's)

Interesting that Megger use it though! Everyday is a school day......

my point was of course that you never MEASURE R1+R2 using three leads, what you saying is that you would measure Zs, and the meter would kick out an R1+R2 from it......... got a meeting with Megger soon, I will discuss it with them!