Assessment on tuesday

[p11jor]

Hi all as I previously posted I cancelled my niceic application and applied for napit so Tuesday is tge day of my assessment.My main work is new build installations oppose to alot of testing, I did my 2392 which was very breif.......so I need to refresh myself on the zs, I understand how to take it and maxium zs for size of breaker etc, the 80% rule. But what else is the zs result used for?Also say I get a reading on a tt system of 5.4 I understand a 100ma rcd to stop nuisance tripping.....as you can see I need a bit of guidance on this!

 

[telectrix]

on a TT system, all circuits need 30mA RCD protection. as the Zs values will be too high for the MCBs to trip within the stipulated time, due to the low values of fault current, you rely on the RCD to give fault protection. your max. Zs values will the be 1667ohms.

 

[ezzzekiel]

to ensure that under fault conditions sufficient current flows to operate the ocpd

Also say I get a reading on a tt system of 5.4 I understand a 100ma rcd to stop nuisance tripping

eh?

 

[malcolmsanford]

Are you sure you are really ready for this.

You do know what the Zs of the circuit is for don't you? And why it is so important to have.

What is this 5.4 your referring to ohms, voltage, the forecast for hackney dog track? Where is the 100mA RCD coming into the equation, is it protecting a sub main?

 

[sparks_114]

Zs will indicate whether the protective device will break/trip in the stated time as laid down by the regs. If your Zs is sky high (say 2000 ohms) then perhaps even an RCD wouldn't trip (1667 ohms is maximum for a 30 mA RCD). Conversely if your Zs is so low (which would mean high prospective fault currents) it may be that the protective device might not be able to handle the said fault currents. In basic language that is it I believe.

 

[p11jor]

Malcolm ohms obviously what a stupid question, the rcd at 100ma I had been advised to put in as main isolator before the board (right or wrong) I don't know hence coming on here for others advice. And yes now the other helpful members have contributed.

 

[malcolmsanford]

Malcolm ohms obviously what a stupid question, the rcd at 100ma I had been advised to put in as main isolator before the board (right or wrong) I don't know hence coming on here for others advice. And yes now the other helpful members have contributed.

Well there you go then sorry that I asked such a stupid question. I obviously have not had the required training in clairvoyance as the other guys. I stand truly corrected.

I don't know son is it needed as a main isolator ?

 

[alanl]

But you are not clear in what you have written, and , to be fair, you have come across as though you are not ready for an Assessment.
I think you'll find that NAPIT are very keen (as are the others too) on your testing procedure, and understanding the results, so you really need to know it off by heart for most common incidences.
You'll be able to look in the book, but you really should know the basics without looking anything up.

Alan.

 

[p11jor]

I am not claiming to be some great test engineer, nor some fantastic spark, I have had a full chat with napit, explained everything about what work I carry out, the fact I don't do PIRs etc, all I do is install then test my installs correctly. Idealy I would be defined scope if they could cover rewires. At 24 years of age given good health I have Many of years left in me to keep learning, I have 2330, 2382 & 2392 so I have done everything possible so far to be a competent person. I am constantly on the lookout for any info that can help my I always have to OSG out picking up on certain parts so I am just trying to go about things the right way hence joining a scheme so 1. My customers are left with a cert and 2. To keep myself in work at these hard times without having to add £280 labc fees on. I have a older semi retired spark working with me age 63 been sparking since 15 an he dosnt have a clue about zs, ze, PFC continuity ring final. But from a installation point of view he's one of the best about.

 

[p11jor]

And Alan my first post was saying I take my zs reading for whatever final circuit it may be get my check it against what type/rating apply the 80% rule to give me the correct disconnection time.Also I know that on a tt system if you have ADOS then that acts as your fault protection etc. Just needed someone with more experience than myself to confirm I am right. Wish I hadn't bothed now confidence is well down now. Cheers

 

[malcolmsanford]

OK settle down son, what is the actual work you did for the assessment, was it a CU change, or what?

Once we establish what you have done perhaps we can move you along.

 

[gooner1984]

look p11jor, don't take it to hart. i don't know the other's to say, but im sure they didn't mean, to offend you, they are just saying, "do you think you are ready "

 

[p11jor]

Rewire, 2 radialsRing for kitchen2 light circuitsCooker circuitSplit loadedThen swa out to garage on RCBO1 unprotected radial feeding one socket next to the board for a Internet and phone plug in due to themNeeding constant supply for work reasons (and yes cable is over 50mm in partition)Oh yer and obv smokesSo pretty good installation to show themAnd to the question "am I ready" here is my answer.....Starting doing PIRs for a living.....NORewiring houses and self certify them....YESFire alarm systems.....YESThree phase installations.....NO

 

[gooner1984]

well good luck for Tuesday, im sure your be be fine, :1eye:

 

[p11jor]

Also to add to that this is part p dwellings scheme which some governing bodies let you in with one of them domestic installers quals which are what....5/10 day courses, So yer am I ready to be in a part p scheme....yes defo