Advertisement - Content continues below
Advertisement - Content continues below

Discuss Live Earth loop testing on light circuits in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

EddieB

-
Arms
Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

Help!! Every time I attempt a live loop test at the light the RCd trips, I have 2 loop testers and both are trip locked but the result is the same with both, so it must be something I'm doing wrong. I have a 3 lead set up which allows me to mate 2 of them together leaving a 2 probes to do the test with. Answers on a virtual postcard please.
 
Advertisement - Content continues below
D

DanBrown

I think you may be doing it wrong mate...
If you connect the 2 probes together to do a 2 lead test, this is a high current test method, and will trip RCD's regardless of trip lock etc..
Do the test using 3 lead method and see if that works. E.G. Live = Live, Neutral = Neutral and Earth = Earth.

What tester are you using??.

Let us know how you go...
 
T

Tiger

When you say trip locked, is this the same as a no trip loop tester.
have you performed this test before on a rcd with sucess.
I'am afraid i only have experiance with a megger and you can't really go wrong with that. Whats your tester
 
If you're sure you are doing the test correctly and the RCD is still tripping, try doing a ramp test on the RCD to see what current it is tripping at. It might be the RCD that is at fault!
 
Help!! Every time I attempt a live loop test at the light the RCd trips, I have 2 loop testers and both are trip locked but the result is the same with both, so it must be something I'm doing wrong. I have a 3 lead set up which allows me to mate 2 of them together leaving a 2 probes to do the test with. Answers on a virtual postcard please.
you need to grow another hand.
your live and neutral both go through the rcd,so you need to be useing your circuit neutral or else put a temporary bypass on your rcd.
 
S

Spudnik

I have had problems sometimes if the probes are not pushed in tight.

Although 2 wire high current loop testing will almost always trip the MCB/RCD.

Like others have said, bypass the RCD or maybe swap it out for a double pole main switch for the purpose of testing.
 
W

WarrenG

I think if you are mating 2 of the three leads together for the three lead test than that is where your problem is.

As Dan Brown has already said if you are using three leads, they all need to be connected to each terminal L. N. E. at the lighting point where you are taking your Zs reading.

If you tester has a low current test (no-trip @ 15ma) then it should not trip the RCD

Let us know how you got on?
 

slocm3105

-
Arms
Without a doubt, use all 3 leads, I was working with a spark who was using two leads on his NEW meter and wondered why it tripped lol. If u got 3 leads, use 3 leads :).
 
S

super spark

Why bother with the Zs test? its unreliable and riddled with parallel paths!

I presume you have already taken your r1/r2 and Ze so just calculate it, its much more reliable and safe.

you wouldn't take a polarity test after continuity so why do people still take Zs ???????

Zs = Ze + (r1+r2) - job done

calculation = reliable, accurate result

meter = Parallel paths (lighting - chrome switches, back boxs, chrome fittings, cpc still connected in MET?)
 

EddieB

-
Arms
  • Thread Starter Thread Starter
  • #12
I fully agree with you S/S, however there is a requirement on the test schedule for a measured Zs
 
G

Guest123

Why bother with the Zs test? its unreliable and riddled with parallel paths!

I presume you have already taken your r1/r2 and Ze so just calculate it, its much more reliable and safe.

you wouldn't take a polarity test after continuity so why do people still take Zs ???????

Zs = Ze + (r1+r2) - job done

calculation = reliable, accurate result

meter = Parallel paths (lighting - chrome switches, back boxs, chrome fittings, cpc still connected in MET?)
Would you not measure Zs after installing an additional light/socket onto an existing circuit at your new point?? By doing this you also confirm correct polarity as most meters will not perform the test otherwise.

You cant add that up.
 
Why bother with the Zs test? its unreliable and riddled with parallel paths!

I presume you have already taken your r1/r2 and Ze so just calculate it, its much more reliable and safe.

you wouldn't take a polarity test after continuity so why do people still take Zs ???????

Zs = Ze + (r1+r2) - job done

calculation = reliable, accurate result

meter = Parallel paths (lighting - chrome switches, back boxs, chrome fittings, cpc still connected in MET?)
What parallel paths??? You don't get them from a "chrome switch,back box or chrome fitting"(unless you are fixing to earthed metal)In a domestic situation the only parrallel path you are likely to encounter are thru the water/gas pipes.
 
S

super spark

Would you not measure Zs after installing an additional light/socket onto an existing circuit at your new point?? By doing this you also confirm correct polarity as most meters will not perform the test otherwise.

You cant add that up.
I would carry out a Ze & r1/r2 test prior to installation to ascertain whether the circuit was capable of carrying the additional load whilst still conforming with max Zs values, then on completion of the addition I would carry out an r1/r2 again.

Yes the NICEIC certificate asks for a (measured value), and as the r1/r2 & Ze values were measured, adding the r1/r2 value to the Ze is still measured.

If you used the designers method then it would be calculated and not appropriate.

What parallel paths??? You don't get them from a "chrome switch,back box or chrome fitting"(unless you are fixing to earthed metal)In a domestic situation the only parrallel path you are likely to encounter are thru the water/gas pipes.
You can encounter parallel paths from the MET, so unless you disconnect the MBC from the MET when carrying out the Zs test these paths will be present.

As a Zs test is live I would not recommend disconnecting the MBC, this could create a dangerous situation

(other poss parallel paths inc... supp bond conductors, steel conduit etc...)

I fully agree with you S/S, however there is a requirement on the test schedule for a measured Zs
As I stated this calculation is still derived from measured values thus it is a measured reading. Calculated Zs is a completely different calculation and much more in depth used by designers.
 
Last edited by a moderator:
Aico Carbon Monoxide Detectors
This official sponsor may provide discounts for members
Advertisement - Content continues below

Reply to Live Earth loop testing on light circuits in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

SuperlecDirect - ElectriciansForums.net Electrical Suppliers
This official sponsor may provide discounts for members
Advertisement - Content continues below
Top Bottom