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I must be confused about some wording,

Light circuit R1+R2 is 1.84 Ze measured = 0.28

So if I do Ze +(R1+R2) I get 2.06

Maximum Zs allowed is 6.14

actual measured Zs is 0.88

This measured Zs is much lower than the max value, I know higher is not good but lower Zs leads to any problems ??
 
make sure you batteries are not low and that you have good connection with your test leads. could also be parrallel paths make earth loop lower
 
Low batteries!! yes I do have low batteries, I wonder if this is the reason. I shoulds change batteries and see. Thanks dwardy
 
I must be confused about some wording,

Light circuit R1+R2 is 1.84 Ze measured = 0.28

So if I do Ze +(R1+R2) I get 2.06

Maximum Zs allowed is 6.14

actual measured Zs is 0.88

This measured Zs is much lower than the max value, I know higher is not good but lower Zs leads to any problems ??[/QUOTE]



You cant expect your Zs to be bang on the maximum every time....it's a maximum for a reason. If a lower than maximum Zs would be a problem we would have to measure Ze before installing any cables,work out the reistance required to reach the maximum and install a length of cable of exactly that resistance....dont happen does it?
 
Measured is always better than a calculated reading

I agree in a way but if calculated is within spec then no need to measure as you're working on live equipment when it isn't necessary just to gain another still compliant figure. You've already measured Ze so know there's an earth path and you've proved the CPC is continuous.
You're also wasting time by effectively doing the same test again......

You may consider this a little over the top but that in itself would contravene the EAWR section 14(a):

Work on or near live conductors

14. No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless–
(a)it is unreasonable in all the circumstances for it to be dead; and
(b)it is reasonable in all the circumstances for him to be at work on or near it while it is live; and
(c)suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.
 
I agree in a way but if calculated is within spec then no need to measure as you're working on live equipment when it isn't necessary just to gain another still compliant figure. You've already measured Ze so know there's an earth path and you've proved the CPC is continuous.
You're also wasting time by effectively doing the same test again......

Defo not a waste of time! Ok so you did your R1+R2 test , which you disconnected at the CU, measuring your Zs is the only way to prove you remade the connections properly and also to establish wether or not there is a possible loose connection in the circuit.
Do it Properly
 
just because you get an earth loop value doesnt mean your cpc is continous. you should ALWAYS do a R1+R2 test
 
Regulations state calculated is an accepted method, and R1R2 tests should be carried out so if you wish to use a calculation or go on and do a live zs either is acceptable - cant see the problem
 
Defo not a waste of time! Ok so you did your R1+R2 test , which you disconnected at the CU, measuring your Zs is the only way to prove you remade the connections properly and also to establish wether or not there is a possible loose connection in the circuit.
Do it Properly

What did I disconnect and reconnect?
To carry out my R1+R2 test I merely add a link between the top of the circuits MCB and the earth bar within the consumer unit. I then go to all areas measuring R1+R2 and record the highest figures. When I've done this with all circuits I remove the link from the earth bar.
That is doing it properly and safely. I think you need an understanding of how to test if you don't agree.
Also, if you can't disconnect a conductor and reconnect with visual verification then you've no right to be in this industry.

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Regulations state calculated is an accepted method, and R1R2 tests should be carried out so if you wish to use a calculation or go on and do a live zs either is acceptable - cant see the problem

No problem but live Zs testing is replicating a previous test but with added dangers of live testing which should be avoided if possible.

Imaging stood on a pair of step ladders with your meter set to no-trip mode due to the circuit being on a RCD. Many testers then require all 3 probes to carry out a Zs test which can be awkward, especially at height. It's just not required.
 
Last edited by a moderator:
What did I disconnect and reconnect?
To carry out my R1+R2 test I merely add a link between the top of the circuits MCB and the earth bar within the consumer unit. I then go to all areas measuring R1+R2 and record the highest figures. When I've done this with all circuits I remove the link from the earth bar.
That is doing it properly and safely. I think you need an understanding of how to test if you don't agree.
Also, if you can't disconnect a conductor and reconnect with visual verification then you've no right to be in this industry.

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Very strong words my friend!!!!
I,ve been doing this for more years than i can care to remember, and on a daily basis (this is my Job)
So you do not disconnect anything? How do you for example verify "Ring Final Circuit" continuity? Ze ? Do it properly= do it once
 
Work on or near live conductors

14. No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless–
(a)it is unreasonable in all the circumstances for it to be dead; and
(b)it is reasonable in all the circumstances for him to be at work on or near it while it is live; and
(c)suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.

I get a bit fed up with this crap Live working regs were never intended to stop people Live TESTING, read the bit in Red.
insulating material...Are the wires and the termination points not 'Insulated' to BS Standards ? Is your tester and leads not to BS Standards and GS 38 ?, why is anyone fumbling around with three probes in a light rose ? buy a set of EZ test adapters and it's a doddle
why is a measured a superior value ? Think about it ? your measuring the whole of the circuit including any terminations that may have nipped down on the insulation


 
Agree with Steve Breeds here. Live working is not live testing IMO. I may choose not to do a ZS test up a ladder on a lighting circuit but we know where to place our insulated probes to test don't we?!
 
Work on or near live conductors

14. No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless–
(a)it is unreasonable in all the circumstances for it to be dead; and
(b)it is reasonable in all the circumstances for him to be at work on or near it while it is live; and
(c)suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.

I get a bit fed up with this crap Live working regs were never intended to stop people Live TESTING, read the bit in Red.
insulating material...Are the wires and the termination points not 'Insulated' to BS Standards ? Is your tester and leads not to BS Standards and GS 38 ?, why is anyone fumbling around with three probes in a light rose ? buy a set of EZ test adapters and it's a doddle
why is a measured a superior value ? Think about it ? your measuring the whole of the circuit including any terminations that may have nipped down on the insulation



Agree with Steve Breeds here. Live working is not live testing IMO. I may choose not to do a ZS test up a ladder on a lighting circuit but we know where to place our insulated probes to test don't we?!

How inconvenient that the HSE and any expert witness in court will not agree with your view. HSR25 Memorandum of Guidance, paragraph 208, specifically states that in respect of EWR:1989 Regulation 14 Live work includes live testing ...
EWR:1989 Regulation 14 does not stop you working live, but you must be able to justify your need to work live, particularly when you have removed any insulating barrier to access the live terminals in order to perform the test eg. CU cover, busbar barrier, pendant cover, lamp holder cover etc.

Memorandum of guidance on the Electricity at Work Regulations 1989. Guidance on Regulations - HSG25
 
Yea and my justification is that a measured value is infinitely superior to a calculated one and always will be, if you use the correct testing equipment, the correct techniques and the knowledge you have as a competent electrician who is trained, what's the problem ? I'll tell you what it is, tree hugging, sandal wearing, muesli munchers telling me that they know better than I do and people like you banging their drum, well when the tree falls on them, they trip over their sandals and choke on the Muesli they may realise that life is risky, tell you what just stay in bed all day buddy, that way you wont go near any live street lamps in case you get a shock off one that has dog wee on it !
 
for me, it depends on the situation. At the moment, the jobs im doing, involve fitting out steel kiosks with wooden lining, with lighting power and a heater. We are using steel conduit on plastic accessories (dont ask). tyhe conduit willbe earthed onto the plastic cu via a banjo, but the tube will not be earthed onto the sockets ect, as we are running a CPC to every circuit.
The CU has an RCD as the main switch. I dont trust the no trip setting on the megger 1552, afdter getting all sorts of readeings different to the high current setting.
So in the situation in the kiosks, i dont have to disconnect anything other than the light fitting for testing, and they are push fits anyway, with no way of getting ypur probes in.
i see no need for Zs in this situation, as there are no paralell paths, and the Zdb (which i do measure) +R1+R2 is accurate.
Where trhere is no RCD, then i measure every time.
 

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