Assessment questions & Test Procedure

[revolt3k]

HI
I have my first Assessment Coming up and thought i would ask you guys a few questions about it.

First of all i know my main tester (Metrel Easi Test) needs to have its anual check and certificate done, how quick can these be obtained by the way. But does my proving unit and volt tester also have to have a cert?


Im hoping to have at least 3 jobs for him to choose from. Will they want me to select one or do they?

If showing him somting like a new circuit for outside lights would the following procedure be about right

Isolate the supply (main swith) by means of lock and key

Place warning notice in the location og isolation (would above the c.u be ok as attaching this to the lock may interfeer with working on the boad its self. What do others do with the notice?

Prove test equiptment for correct working

Test between L - N > L - E > N - E

Prove test equiptment for correct working after to make sure the equiptment was working

At this point i would add the cover back to the C.U and take out all lamps and tubes on the outside lights. Is this correct?

Dead Tests

I would test for continuity of protective conductors (R1+R2) link out the 1.5mm live and earth at the end of the circuit (last light) with a block, then null my machine and test. and record the result.

Would a test of L - N be required?

I would then test insulations reisitance. Remove the link and seperate the conductors at both ends.
Test IR between L - N > L - E > N - E and record the results.

At this point Polarity would be check and by doing R1+R2 i should have confirmed the correct polarity


Live Tests

I would first test for Ze at the C.U. With all conductors connected into the terminals and lamps and covers installed.
I would remove the main 16mm earth and connect the eath clamp from the easi tester and then test before the main switch as to not make the installation live with no earth pressent. I would record the 2 readings ohms is my Ze and Amps is the PFC (reconnect earth)

Zs - As the lights are outside and half way up the wall i wouldnt do a live test for Zs at the lights as this doesnt really confirm with H&S EAW regs and so i would calculate the Zs by means of Zs = Ze + R1+R2
and record this.

RCD Test.
This circuit is protected by a 6A - 30Ma RCBO to make sure the circuit is 17th edition ect

What would be the best way to test this without going up ladders in the rain and attaching leads etc.

Once the tests were complete and results checked & logged. I would make sure all conductors and accessories are back in place and remove the isolation.


Any advice and criticism welcomed as i would like to make sure im doing things as should be

Dave

 

[Archie]

Sounds perfect,

Make sure you have all the paperwork i.e.
Electricity @ Work Regs memorandum
17th Regs
On Site Guide
Part P
Risk Assessments & Method Statements
PL & PI insurance
Copies of issued certs, estimates & invoices etc

I'm sure you'll pass

On one of my assessments I took the NICEIC Engineer to the Cafe for a massive blow-out breakfast, after that he was too bloated & sleepy to to do much else

 

[Spudnik]

Dave,

The jobs that you take him to should already have test results, otherwise the installation should not have been energised.

Once on site, he will tell you what tests to do and he may also ask you to interpret what the results mean, not just what they are.

Good luck.

 

[revolt3k]

Dave,

The jobs that you take him to should already have test results, otherwise the installation should not have been energised.

Once on site, he will tell you what tests to do and he may also ask you to interpret what the results mean, not just what they are.

Good luck.

thanks, yeah i know the results will be on my cert that i did for that job already at the time it was installed.

So basically if he says why is the results from the IR 20M and not 800M i should be giving him an answer like due to cable age the insulation is deteriorating or the UV from the sun is causing deteration. Or maybe a lamp holder is starting to ware. If the results were 800m to start with then the answer would maybe be that the install is new and the IR is good due to new cables and accessories.

On a small light circuit like 3 outside lights the R1 + R2 would have low readings due to short ish cable runs with 1.0 or 1.5 milli cable. If the reading was really high then bad terminations could be the cause and investigation should be carried out.

would this be somtihng like?

Any help you guys can prove i am VERY greatfull for. Im new to this area being assessd etc

many thanks

 

[Spudnik]

Sounds good to me.

But heres a couple:

Why are we testing R1 + R2 and not just R2?

What are the maximum trip times in ms for a 30mA RCD at x1 and x5?

Why do we test Zs?

No cheating!

 

[revolt3k]

Sounds good to me.

But heres a couple:

Why are we testing R1 + R2 and not just R2?

What are the maximum trip times in ms for a 30mA RCD at x1 and x5?

Why do we test Zs?

No cheating!

Okay well i think with R1 + R2 we test this way to both confirm continuity of the Live and Earth conductors and to confirm the correct polarity at the same time?

30Ma RCD at 1x i think this is 40ms? and i cant seem to remember x5 (somthing i need to brush up on)

Zs - To check that the earth path back to the main supply transformer is good enough to provide a hight enought fault current to trip the protective device quick enought. .4 for sockets and 5seconds for lights and fixed equiptment.


Thanks for your replies by the way. This place is great for sharing and helping others.

Sorry i forgot to ask how could i test the RCBO protecting the outside light circuit withount working live up the ladder ( big no no)

 

[Spudnik]

Okay well i think with R1 + R2 we test this way to both confirm continuity of the Live and Earth conductors and to confirm the correct polarity at the same time?

30Ma RCD at 1x i think this is 40ms? and i cant seem to remember x5 (somthing i need to brush up on)

Zs - To check that the earth path back to the main supply transformer is good enough to provide a hight enought fault current to trip the protective device quick enought. .4 for sockets and 5seconds for lights and fixed equiptment.


Thanks for your replies by the way. This place is great for sharing and helping others.

Sorry i forgot to ask how could i test the RCBO protecting the outside light circuit withount working live up the ladder ( big no no)

Where is the supply?

Is the circuit for the outside light behind the switch?

If so, test it there.

 

[revolt3k]

Where is the supply?

Is the circuit for the outside light behind the switch?

If so, test it there.

No, just a twin run from a 6A RCBO to 3 PIR floods

 

[Spudnik]

No, just a twin run from a 6A RCBO to 3 PIR floods

Hmmm.

Gotta be honest. You should ideally have local isolation for these lights, even if its a switch by the back door or similar.

 

[revolt3k]

Hmmm.

Gotta be honest. You should ideally have local isolation for these lights, even if its a switch by the back door or similar.

ok, would a 20A double poll isolator work next to the cu maybe?

 

[Spudnik]

ok, would a 20A double poll isolator work next to the cu maybe?

Yep that should be fine, and maybe a label to say what it does.

That way you could also test the RCBO from there.

 

[revolt3k]

Yep that should be fine, and maybe a label to say what it does.

That way you could also test the RCBO from there.

Just a quick on, If you were carring out an RCD test from the 20A double poll isolator for the lights how would you connect the leads and carry out the test.

thanks again

 

[kung]

Also a habbit i have before an IR test is switch back to continuity and do a quick lead test just in case there is an open circuit in the lead and your meter on a 500v test would give a reading of greater than 299 meg ohms and fool you into thinking youve tested the circuit and passed it when in fact you havent tested anything at all.

 

[revolt3k]

Also a habbit i have before an IR test is switch back to continuity and do a quick lead test just in case there is an open circuit in the lead and your meter on a 500v test would give a reading of greater than 299 meg ohms and fool you into thinking youve tested the circuit and passed it when in fact you havent tested anything at all.

Cheer Kung,

What about the live RCD test mate?

 

[kung]

Hi Revolt3k
You shouldnt need to test lead for RCD testing as if the RCD opperates in required times then you know the leads fine as well and if not a quick continuity test using a multimeter will still prove lead is ok. But if you mean in refferance to your question about the testing at the isolator a live RCD test it will contravine reg 14 of EAW regs so only perform RCD tests at socket outlets mate.
Regards
Kung.