3 step test on ring final circuits

[sparkyork]

hi guys n gals,

just swotting up on some test procedures and im wondering how many of you do a 3 stage test on ring main circuits? i know from previous employers on a new build for instance, they just wanted me to get the end to end results and then go round to every socket and record which one has the highest reading?

are there different rules for new builds or were they just a bit rough!! i can see why they wanted me to do it this way as it would take a bit longer to do the full 3 stage test.

thoughts and comments anyone?

rich

 

[PAUL M]

i allways do the full test just to be on the safe side.

 

[spark-doctor]

Look at page 69 of the OSG. The 3 stage test is one of the three to be carried out in a sequence so if you only did one you would not be completing the sequence and i think you would fail your assessment.

Get out clause!
I am NAPIT so not quite sure on NIC rules but with NAPIT you have to do the 3 tests.

Good Luck.

 

[sparkyork]

cheers, i intened to do the full 3 stage test if i get asked to do the ring test that is.
just thinking about previous employers who only wanted end to end readings, then highest Zs reading from a socket outlet.

 

[PAUL M]

depending on who you get at your assesment he might just ask you to do the live/cpc sequence to obtain your R1 +R2,BUT BEST TO PREPARE FOR THE WORST.

 

[sparkyork]

yeah true! another ponder! ive got a pair of uninsulated croc clips that i use to do these sort of things, general linking of stuff at the consumer unit for test purposes, only used when the main switch is off and locked off. are they likely to moan about these as well, cant be arsed spending £20 on some fancy clips

 

[greekislandlover]

Although you should be prepared to do the full test if asked, I think you may get asked to discuss the method rather than do it in practice. On our NIC annual check, AFIK the inspector hasn't asked to see anyone do this - they have usually accepted continuity, IR highest Zs and RCD tests. Maybe because they must know that (as you state) it's not an uncommon practice.

I seem to recall that this time we got picked up on somebody calculating R1 +R2 by taking Ze from Zs, whereas the previous inspector had other views. So if doing radials (obiously not sockets!) make sure you measure Ze and R1+R2 and calculate Zs rather than the other way round. Measure Zs in any case, but the reading to note is the Zs=Ze+(r1+r2) calculation.

Even though the NIC are money-grubbing, I don't think the inspector is out to trip you up on purpose. Provided you can demonstrate sound knowledge you should be OK.

 

[sparkyork]

thats exactly how ive filled out my domestic installation certificate! worked out r1 + r2 by calc, is he gonna pull that then or just if i do the test in this way for him to see? ive always been taught to do it this way when testing.

sooner i do me 2391 the better i feel!?

 

[wayne]

its good to see someone like rich trying/planning to improve things .good luck with your assess

 

[spark-doctor]

I will be bloody well glad when he has passed it and we can go back to looking at women sitting on rocks with little on

Seriosly, remember the 6 P's, Proper Preperation Prevents P**s Poor Performance, which you seem to be doing.

Get rid of the uninsulated croc clips though, my asser ripped me a new one for using them when he saw a insulated set in my tool box.

just rememeber the asser is not there to trip you up just to make sure you are compertent to do the work. My asser told me that most people fail because of the basics such as safe isolation, forgeting your copy of BS7671.

 

[sparkyork]

cheers wayne, im always willing to learn but then you gotta in this game or you get left behind!!
ill go out and buy some nice crocs then. was in me wholesaler today looking at some, things is they have the clips, but the linking wires that plug into em are about 600mm long!! only need 200mm max

anyone know where you can get shorter GS38 style leads that are this long and plug into croc clips!!??

rich

I will be bloody well glad when he has passed it and we can go back to looking at women sitting on rocks with little on

Seriosly, remember the 6 P's, Proper Preperation Prevents P**s Poor Performance, which you seem to be doing.

pi%%ed my little white Y fronts!!

 

[greekislandlover]

thats exactly how ive filled out my domestic installation certificate! worked out r1 + r2 by calc, is he gonna pull that then or just if i do the test in this way for him to see? ive always been taught to do it this way when testing.

sooner i do me 2391 the better i feel!?

I did 2391 recently (couple of years ago) and they said to measure Ze and add (r1+r2), so I'd say go with that for the test, but just check the Zs measures something sensible as a precaution. Show willing like.

I know you can argue this point several ways, but the previous NIC inspector felt that proving the Zs at the end of line by meter was better than calculating it.

 

[sparkyork]

yeah if need be ill do the test the "proper" way then like u say confirm Zs with a meter, which i agree is the best method of varifying the circuit.

 

[Carter]

Look at page 69 of the OSG. The 3 stage test is one of the three to be carried out in a sequence so if you only did one you would not be completing the sequence and i think you would fail your assessment....

Agree with all of that. The Continuity of Ring Final Cct. Conductors test is a pre-requesite to the integrity of any subsequent tests. Among other things, a partial test doesn't provide a sound legal basis on which to legitimately proceed to the next test stage. (ie live testing)

 

[Shakey]

yeah if need be ill do the test the "proper" way then like u say confirm Zs with a meter, which i agree is the best method of varifying the circuit.

be carefull with the Zs tests , Rich

I have an NIC training video in my possesion, and they like C&G on 2391/2392 exams are invoking the EAWR principle of ONLY measuring Zs when there is no other way to obtain the reading and only when it is acceptably safe. Arguably, if you have Ze, and (R1+R2), then if you measured Zs at say, a ceiling rose, he could (and should) question you on why you doing it

There is a stock answer you can give him mind.........