2391 - function testing ?

[Womble]

Hi all, i have my 2391 practical exam coming up on thursday (22nd March) im currently running through all the tests, and making a publication showing a list of tests where i can just fill in the values for each test, ive come to the function tests section, as i see it i would add lamps back in again, and switch each of the lighting circuits, so dimmer, and the normal 2 way switch.

Although for the fussed connection unit (spur) how can i function test this ?, there is no load on it, just a pyro cable run, and a metal clad spur

any help would be apprecieted as i feel daft asking such a simple question !!

 

[trev]

Functional testing is just that mate. Does it function as it should?

 

[Adam W]

If you're doing a long lead R2 test you could move the probes over to the busbar and live load and operate the switch, which will prove operation of the switch.
That will test the polarity as well.

Do you know anything about doing the Zs on the lighting circuit with the dimmer?
Presumably you can't leave it linked out, and you wouldn't have to go through safe isolation again, so do you have to calculate Zs?

 

[Womble]

I think what i'll do is a quick resistance test (low resistance ohmeter ) and quickly check the switching of the spur during the dead tests, means i can just leave the energized test as ive already done it

Adam, your Zs can be calculated from Ze + (R1 + R2), so if you get your Ze reading during the earth fault loop impedance test, you can fill in the Zs column on your schedule of test results by adding the R1+R2 values for each circuit ?

Meaning you can just use Ze throughout and just calculate everything for your Zs value

 

[brucelee]

you dont need to do any functon check jsut the polarity check when doing the continuity of protective conductors
jsut operate the light switches
use socket adapter ( martindale to see working correctly )
dont forget to operate the test button of the rcd after you have done your rcd tests
operate cbs its not that bad mate just take your time and not rush

dont forget to ask for old test sheets
fill in what you can of them and then
start inspecting visually the set up and operate the lights so you can see what switches what
then seek permission to isolate
locate and isolate lock off retain key in pocket POST WARNING NOTICE
also switch off the singLe phase board
then select gs38 voltage indicator prove working on known supply or suitable proving unit
test at the 3 phase board 10 point test
L1-L2,L1 -L3, L2-L3,
L1-N,L2-N-L3-N
L1-E,L2-E,L3-E
N-E
then check approved votage indicator working agin on known supply or proving unit
BEGIN CONTINUITY OF PROTECTIVE CONDUCTORS (INC MAIN AND SUPP BONDING
which can be done before the final circuit protective conductors
thinks you will have that in your head already

dont forget to put the key in your pocket or you will be shot with lighting bolt and fail

jsut calculate the Zs of all circuits except the sockets

your Zs for the supply to the single phase board is also the ze for that board
so to get the zs of the single phase final circuits

except for sockets which you can measure
use
Ze +(R1+R2) for the supply to single phase board then add (R1+R2) of the singel phase board to get
the Zs for the single phase final circuits

Good Luck mate

 

[Adam W]

Meaning you can just use Ze throughout and just calculate everything for your Zs value

I think I'll be measuring Zs wherever possible - just calculate it for the 3 phase socket and the lighting circuit with the dimmer. Calculating it everywhere is fine in theory, but the theory doesn't always transpose into reality.

 

[Womble]

"BEGIN CONTINUITY OF PROTECTIVE CONDUCTORS (INC MAIN AND SUPP BONDING)"

This is just to fill out the inspection report i imagine ? no values will be recorded as such, as for the main earthing conductor, just link out in the 3 phase board, and measure between the pins on the plug he uses to energize the test rig ?

 

[Adam W]

You'd take the main earth out of the MET and test between the end you've just taken out and the earth in the DB.
Take the main protective earths out of the MET and test between the end and the service pipe(s); I think on the exam rig there's only a water pipe.
You don't record the figures, just verify connection.

 

[brucelee]

I think what i'll do is a quick resistance test (low resistance ohmeter ) and quickly check the switching of the spur during the dead tests, means i can just leave the energized test as ive already done it

Adam, your Zs can be calculated from Ze + (R1 + R2), so if you get your Ze reading during the earth fault loop impedance test, you can fill in the Zs column on your schedule of test results by adding the R1+R2 values for each circuit ?

Meaning you can just use Ze throughout and just calculate everything for your Zs value

meaning you can use Zs =Ze +(R1 +R2)for the three phase
and then for single phase baord
Zs =Ze+(R1 +R2) + (R1 +R2)
the only circuit you need to measure Zs is the socket oultet circuit
as this is exactly what i did saves time
and when calculating gives a true reading as the measured is lower because of parallel earth paths
as long as it complies calculated it will comply when measured