Easy Test

[Nicky Tesla]

All the books tell you to isolate the electrics by switching off the DB, then put in a temporary connection between the busbar or phase conductor to the earth bar, and then to take a reading at the accessory to get r1+r2.

After you have done this you may need to refit the accessorys in an occupied house, remove the temporary link, and then go round undoing all the fittings again to get a Zs reading at fused spurs etc.

My way saves loads of time and inconvenience.

r1 is normally thought to be the phase conductor, but it is actually the neutral conductor also. What I do, is undo the accessory, take r1+r2 on the live cct but from neutral to earth, then take Zs readings as normal and then refit the accessory. Job Done.

If there is an RCD on a split board, the r1+r2 test will trip it out still, so just put in a temporary link between the two neutral bars. Easy.

 

[kme]

I find it hard to believe that you are not trying to wind us all up NT. You cannot be seriously suggesting this as a valid testing method???????????

The reason "all the books" tell you to do it that way is for a very good reason. Your results would be very different to any of ours. If you actually do your tests like this, then you should take up a different career - traffic warden for instance.

I`m not going to explain the issues with your method. It`s pretty self-evident. Think about it..........

KME

 

[Nicky Tesla]

Try it both ways, same results.

it is AC remember r1 relates to both conductors, neutral is often referred to as a live.

The neutral will be the same csa as the phase and run in the same cable. If you get an odd result from the Zs test, then double check your readings.

I dont see much point in doing r1+r2 readings on existing wiring anyway most of the time cos you get all the info req from Ze and Zs. r1+r2 readings are necessary only to make sure that BEFORE you switch the power on, when installing a NEW cct that the Zs reading will be what is required.

 

[binky]

I dont see much point in doing r1+r2 readings on existing wiring anyway most of the time cos you get all the info req from Ze and Zs. r1+r2 .

There is nothing wrong with calculating r1/r2 from Ze and Zs. I usually do Zs first on existing installs because it gives some idea of state of system, however, r1+r2 is also to check for cross connection of ring circuits and starting at some point along the circuit is risking missing a problem. It is also good practice to repeat Zs or do a ZE through the MCB to ensure cables have been re-connected properly in CU before leaving site

 

[Nicky Tesla]

I always do the continuity tests on the ring ccts.

If i get infinity on say the phase. I put the earth and the neutrals back in the terminals, but put only one of the phase conductors in with the neutrals.

I then go round each socket checking for continuity between L+N and note at which ones I get readings and which i get infinity. With the readings you can work out the route the wiring takes to see the sequence they go round in. Then I swap the L in the neutral terminal and repeat the above. From the readings you can see which is the last socket in the sequence from both sides to work out where the cable will be between that has been cut.

The first thing to do after you know between which sockets the faulty cable is, is to check the walls above for rawlpugs and nails. I did this the other day and it worked a treat.

 

[wally]

Regarding the text book method of shorting out at c/u & testing at accessory. I havnt looked up the text book but this seems wrong to me. I always short out at the accessory & disconnect r1 & r2 at c/u & take the reading here. Doing it the other way will include parralel earth paths inc any cross bonding so in my eyes it could be an incorrect reading (lower than what it actually is)

 

[SPECIAL LOCATION]

The neutral will be the same csa as the phase and run in the same cable.

On a lighting circuit looped to ceiling roses.. with live & switch live dropped to the actual switch..

"R1" (the phase or line conductor) will be longer than the "N" neural conductor?

also it is not uncommon to come across 1.5mm to light fittings..

dropped to switch as 1.0mm?

with a large room with two way switching..

you could be adding quite a few meters on 1.0mm into the circuit!

with 10m of 1.0mm would add 0.18ohms onto your R1+R2 reading?

just a though to consider?

 

[welshwizard]

Nice one, Trailer Boy.

 

[kme]

Regarding the text book method of shorting out at c/u & testing at accessory. I havnt looked up the text book but this seems wrong to me. I always short out at the accessory & disconnect r1 & r2 at c/u & take the reading here. Doing it the other way will include parralel earth paths inc any cross bonding so in my eyes it could be an incorrect reading (lower than what it actually is)

The revised method is NOT to put a link between busbar & earth block. Apparently, some wazzock left his link in place when energising circuit. OOPS

The relevant phase & cpc conductors should be removed from their respective terminations, and shorted - AT the CU!

Nicky - et al specloc`s post; but also to note that you SHOULD be checking polarity at the same time (or do you do an extra [dead] test for this - thus negating the "time-saving" generated by doing the test incorrectly in the first place)?

Wally - you short out every accessory, and then return to cu to do test?

??????? Why, may one ask?

The testing procedure has been designed the way it is for a specific set of reasons. To mess with it in the way NT suggests strikes me as the sort of thing a first-year student, on having his first explaination of testing procedure, would come up with as an "alternative"

Don`t you think that better minds than yours (or indeed mine) have devised the BEST & SAFEST way of testing electrical wiring? Admittedly, we ALL have small tricks that may "round off a corner or two"; but you`re basically substituting R2Rn (which is a seperate test on a s/o circuit, for the R1R2.

You will note - the neutral conductor is NOT R1. It is Rn

NT - Could you explain how you confirm polarity, as a dead test, on, for instance, a lighting circuit? I`m honestly curious.

 

[Nicky Tesla]

The revised method is NOT to put a link between busbar & earth block. Apparently, some wazzock left his link in place when energising circuit. OOPSThe relevant phase & cpc conductors should be removed from their respective terminations, and shorted - AT the CU!

Nicky - et al specloc`s post; but also to note that you SHOULD be checking polarity at the same time (or do you do an extra [dead] test for this - thus negating the "time-saving" generated by doing the test incorrectly in the first place)?

Wally - you short out every accessory, and then return to cu to do test?

??????? Why, may one ask?

The testing procedure has been designed the way it is for a specific set of reasons. To mess with it in the way NT suggests strikes me as the sort of thing a first-year student, on having his first explaination of testing procedure, would come up with as an "alternative"

Don`t you think that better minds than yours (or indeed mine) have devised the BEST & SAFEST way of testing electrical wiring? Admittedly, we ALL have small tricks that may "round off a corner or two"; but you`re basically substituting R2Rn (which is a seperate test on a s/o circuit, for the R1R2.

You will note - the neutral conductor is NOT R1. It is Rn

NT - Could you explain how you confirm polarity, as a dead test, on, for instance, a lighting circuit? I`m honestly curious.

Some wazzock left his link in when energising cct,.......To put a link in to the busbar, you dont actually have to put it directly on the busbar, you just put your link in one of the MCB terminals pref 6A, and this joins to the busbar, this way, if you do accidentally switch on, the mcb will trip, no probs and easier to do.

The switched live thing.....How easy is it to add the resistance from live to switch live at the ceiling rose. You can even pull out the live to the switch to stop you having to switch the mcb off. Or you could just take the Zs and and make adjustments.

Polarity on a dead test......There is only continuity between neutral and earth via the pme connection at the incomer. You need to keep the main switch on. There is no continuity between live and earth, especially if there is no supply power

 

[Nicky Tesla]

The relevant phase & cpc conductors should be removed from their respective terminations, and shorted - AT the CU!

Christ, how long would that take

 

[SPECIAL LOCATION]

(i)

There is only continuity between neutral and earth via the pme connection at the incomer.

(ii)

You need to keep the main switch on.

(iii)

There is no continuity between live and earth,

(iv)

especially if there is no supply power

(v)

The relevant phase & cpc conductors should be removed from their respective terminations, and shorted - AT the CU! Christ, how long would that take

(vi)

To put a link in to the busbar, you dont actually have to put it directly on the busbar, you just put your link in one of the MCB terminals pref 6A

(i) Unless its NOT a PME installation ?

(iii) live & earth ? a neon indicator or something left switched on would have a path from live - neural & thus earth?

(ii) & (iv) Are we talking here of "new build" type installations before supply connected? as you are talking of main switch on but no power?

I initially was under the impression you were looking at existing "Live" installations as you talked about taking live Ze test?

At what point do you verify there is no parallel earth neutral path distorting readings? i.e. are you checking Insulation resistance between neutral & earth first? ?:|

(v) Not much longer that doing (vi) I would suggest?

 

[Nicky Tesla]

(ii) & (iv) Are we talking here of "new build" type installations before supply connected? as you are talking of main switch on but no power?

I initially was under the impression you were looking at existing "Live" installations as you talked about taking live Ze test?

At what point do you verify there is no parallel earth neutral path distorting readings? i.e. are you checking Insulation resistance between neutral & earth first?

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You aint arf argumentative, looking for every little thing that might destroy my technique

Keep trying you aint done it yet.

I was asked earlier about doing the above on a DEAD test. Sometimes you know, the power supply companies actually cut off a supply, especially when the house has been empty for a while, and sometimes there is an empty token meter. Amazing I know.

(v)Not much longer..........Who are you kidding

(vi) I would suggest..........I dont know what youre trying to say, are you agreeing disagreeing, what?

Are you checking insulation resistance between neutral & earth............of course, dont you do insulation tests?

 

[SPECIAL LOCATION]

(You ain't arf argumentative

Well actually I was just trying to clarify one or two points from your method? ?:|

In much the same way I would try and verify points from other peoples posts that I didn't fully get my head round....

which in my book is "discussion & debate".

(looking for every little thing that might destroy my technique

See paragraph above. who mentioned destroying anything? ?:|

I am just trying to help clear up any areas of confusion that may lead others up the wrong path.

(Keep trying you aint done it yet.

What sort of statement is that then?

constructive?

discussion?

or a person trying to provoke an argument?

I am not interested in that sort of game... :|

But if you do want to discuss practical issues relating to the thread then fine..

On you opening post you talked of Zs on live installations...

Now we are talking of dead installations..? ?:|

You initially gave impression the method is suitable for all installations..

You are now talking of PME..? ?:|

It is hardly a greater effort to remove a couple of wires phase & earth and strap them together at a connector block to do R1+R2, readings at accessories... ?:|

And as I pointed earlier R1+R2 on lights.. I would say is quicker doing the proper reading, than fiddling working out additional calculations for switch drops later.

Also while those wires are off you could do your Insulation Resistance tests.

Because as you will be aware it is not uncommon on older installation to have to separate circuits off because of the parallel impedances reducing the overall Insulation resistance of the whole installation.

That is assuming most accessories are still connected and you are doing Phase & Neutral combined with reference to Earth?

Cuz it does take a lot longer if you are going to go round the whole property unplugging everything.

Those are just my thoughts..

If you consider that an "argument" and "trying to destroy techniques"..

well I am sorry Nicky that you feel that way...

but its a free world you can think what you like.. :|

But that is not what is intended or indeed what I think.

I will be perfectly honest with you.. When I am doing a PIR..

Its about me verifying to my own satisfaction that the readings and observations I put on the sheet

that I am signing are accurate and correct!

Its not about get in - get out as quick as possible to get some values?

I would hate to think I had got a continuity reading for a circuit that was actually open...

but was reading a parallel path through some bonding or and an appliance or accessory still connected somewhere?

 

[kme]

You aint arf argumentative, looking for every little thing that might destroy my technique

Keep trying you aint done it yet.

I, for one, wouldn`t want to "destroy your technique" Nicky.

I don`t need to look for "every little thing". There are a number of very big things that jumped off the screen and bit me!

Your technique is flawed! It`s that simple.

Testing isn`t a race. It takes as long as it takes. You want to get in, do half the dead tests, and an efl, and whoopee - you`ve done!

Only thing is - you haven`t done anything except a half-hearted prod about, which proves nothing.

Do you have a scam provider? Have you used "your technique" during the assessment? Thought not mate.

We`re not being argumentative. At least, I`m not. I`m simply stating a fact, to wit:

Your testing technique is wrong. No grey area on this one - its right or its not. Yours isn`t. I`m sorry if you disagree, but you are incorrect.

KME

 

[kme]

Well actually I was just trying to clarify one or two points from your method? ?:|

In much the same way I would try and verify points from other peoples posts that I didn't fully get my head round....

which in my book is "discussion & debate".



See paragraph above. who mentioned destroying anything? ?:|

I am just trying to help clear up any areas of confusion that may lead others up the wrong path.



What sort of statement is that then?

constructive?

discussion?

or a person trying to provoke an argument?

I am not interested in that sort of game... :|

But if you do want to discuss practical issues relating to the thread then fine..

On you opening post you talked of Zs on live installations...

Now we are talking of dead installtions..? ?:|

You initially gave impression the method is suitable for all installations..

You are now talking of PME..? ?:|

It is hardly a greater effort to remove a couple of wires phase & earth and strap them together at a connector block to do R1+R2, readings at accessories... ?:|

And as I pointed earlier R1+R2 on lights.. I would say is quicker doing the proper reading, than fiddling working out additional calculations for switch drops later.

Also while those wires are off you could do your Insulation Resistance tests.

Because as you will be aware it is not uncommon on older installation to have to separate circuits off because of the parallel impedances reducing the overall Insulation resistance of the whole installation.

That is assuming most accessories are still connected and you are doing Phase & Neutral combined with reference to Earth?

Cuz it does take a lot longer if you are going to go round the whole property unplugging everything.

Those are just my thoughts..

If you consider that an "argument" and "trying to destroy techniques"..

well I am sorry Nicky that you feel that way...

but its a free world you can think what you like.. :|

But that is not what is intended or indeed what I think.

I will be perfectly honest with you.. When I am doing a PIR..

Its about me verifying to my own satisfaction that the readings and observations I put on the sheet

that I am signing are accurate and correct!

Its not about get in - get out as quick as possible to get some values?

I would hate to think I had got a continuity reading for a circuit that was actually open...

but was reading a parallel path through some bonding or and an appliance or accessory still connected somewhere?

Sneaked in ahead of me bud.................

But agree with above plus:

We can also confirm dead polarity with the "original technique", esp. with regard to lighting circuits.

Submit your procedure on the IET; and see if they include it in the OSG. Surely they will, if it`s so much better than the existing system.

 

[Nicky Tesla]

Sorry lads if ive upset anybody, but at least ive provoked a response

The PME thing, I was waiting for somebody to mention that, as well as the switched live thing,while waving a finger of disapproval in my face saying "yeh but!"

Ive done the tests both ways, and definitely find my way quicker giving the same results in the same house. Visiting each accessory only once while still live which is a bonus in an occupied house keeping things safe and the kettle boiling.

I guess you lot just dont want to go home early cos youre misses might make you do the hoovering . :^O

 

[wally]

Just to clarify my post folks. I switch off the mcb & disconnect N & E from the C/U, this avoids parallel earth paths. I then find the furthest light on the circuit & test R1 & R2 at eighter this fitting or at the C/U end, it all depends which end I short out R1 & R2. The reading should be the same whichever end you use.

 

[SPECIAL LOCATION]

Sorry lads if ive upset anybody, but at least ive provoked a responseThe PME thing, I was waiting for somebody to mention that, as well as the switched live thing,while waving a finger of disapproval in my face saying "yeh but!"

Ive done the tests both ways, and definitely find my way quicker giving the same results in the same house. Visiting each accessory only once while still live which is a bonus in an occupied house keeping things safe and the kettle boiling.

I guess you lot just dont want to go home early cos youre misses might make you do the hoovering . :^O

Good evening KME m8..

here's a laugh for you..

I had this dream that a bloke posted some utter garbage on this er forum?

twas something like the example post I invented above..

my answer was something like this....

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

I would have thought a person with an HND in electronic would realise that and extra 10m of 1.0mm @ 0.0181ohm per metre would add an extra 0.181 ohm on to the values?

But there again these are just basic electrical science using Mr ohms favourite rules & laws...

as per published figures by IEE..

Spose there is the risk that Non-experienced spark with cheap test gear may not be able to differentiate expected values? ho hum!

Thank you Mr Tesla for a very informative and non argumentative post..

(spot the plonker Rodney.. answers on a postcard to steptoes horse please. )

From YOUR post #13 on this thread...

(vi) Are you checking insulation resistance between neutral & earth............of course, dont you do insulation tests?

At what point are you doing these tests on your "LIVE" installation..?

with the kettle boiling..... so you can get home early ?

Many of your points are very clearly clarified now..

Just to summarise for the benefit of all concerned..

More "waffle" than a "potato waffle"!

Yep! thats about it in a nutshell?

goodnight... So long and thanks for all the fish...

oh by the way....

I think you will find it even quicker to just stick "42" in all the values on your cert..

Here I am Brain the size of a planet... and he asks about hoovering..

I am sure ALL of the true gentlemen sparks on here do the hoovering AND The washing up.. AND put the kids to bed as well... ; \

Its what we live for! :x :x:x:x:x:x:x:x]

- - - - - - - - - - - - - - - - - - - - - - - - - - - - -

so whad aya reckon KME?

was it a dream.... nightmare.. carry on film... A UFO.... Captain scarlet...

Bagpuss... Monty Python sketch...

Or just on of our normal off-the-wall beer chats?

Hope you had a good start to the week m8?

 

[kme]

Sorry lads if ive upset anybody, but at least ive provoked a response

Yes - If you call making yourself look an utter wallaby counts as "provoking a response"

The PME thing, I was waiting for somebody to mention that, as well as the switched live thing,while waving a finger of disapproval in my face saying "yeh but!"

Why? It stood to reason that anyone with a basic understanding of the aims of proper testing would realise that your system was massively flawed. Now you seem to be suggesting that you do R1R2 (actually R2Rn) with a neutral to earth link, WHILE THE INSTALLATION IS ENERGISED??????

You obviously don`t understand the inherent dangers this poses, to you and anyone else within the property at the time.

Ive done the tests both ways, and definitely find my way quicker giving the same results

*****Pardon me - male cow poo alert*****

in the same house. Visiting each accessory only once while still live

I only visit them once whilst live - AFTER visiting them DEAD.

which is a bonus in an occupied house keeping things safe and the kettle boiling.

Safe?? SAFE?? Your testing procedure is about as safe as the Ebola virus!

I guess you lot just dont want to go home early cos youre misses might make you do the hoovering . :^O

Not at all. I simply will not leave the premises until I am satisfied with it`s safety. I like to be able to sleep at night, without wondering if arrogance or negligence will kill someone today.

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Thanks SL - Busy but good. Had 2 immersions to change today; after not having had 1 for a year or so. 1st was ok; but the second was almost welded to the tank, and the damn thing started buckling when I tried to remove it.

Cue cylinder change. Finished that 5.00 tonight.

You ok? You haven`t had any more of Theo`s home brew have you?

You really went funny m8 - started having these nightmare things.........

Did you ever watch Brian Conley on Saturday nights?

I read someone`s post, and "Dangerous Brian" sprung to mind!!!