3 Phase Testing.. Filling Out Cert?

[TPES]

Im after some advice, I'm adding a new 3 phase circuit, from the CU a few meters away to an isolator. Can some one help me out on how to fill in the certificate for this new circuit. an example of a cert filled out would help alot if anyone has one. Does it matter what phase you do your continuity test from?
What do i do when i come to IR test.. Obviously my cert has a box for phase/phase.. but what about the other phases..

Just a bit confussed..

Thanks

 

[Guest123]

Exactly the same as single phase, only do things 3 times.

On a 3P circuit you will have 3 lines for each one (L1, L2, L3) so you can put down the 3 readings.

R1+R2 = L1-E, L2-E and L3-E.

For phase-phase I/R, test between each of the phases - L1-L2, L1-L3, and L2-L3, if new circuit they'll all be >999Mohms or >200Mohms depending on your meter.

 

[electricAl]

For phase-phase I/R, test between each of the phases - L1-L2, L1-L3, and L2-L3, if new circuit they'll all be >999Mohms or >200Mohms depending on your meter.

...or even >299 Mohms if you have the little known Megger 1502/1552/1553

 

[TPES]

Exactly the same as single phase, only do things 3 times.

On a 3P circuit you will have 3 lines for each one (L1, L2, L3) so you can put down the 3 readings.

R1+R2 = L1-E, L2-E and L3-E.

For phase-phase I/R, test between each of the phases - L1-L2, L1-L3, and L2-L3, if new circuit they'll all be >999Mohms or >200Mohms depending on your meter.

Ok, I think i got ya

So for the 1 circuit im adding i will write down 3 seperate lines of results on the cirtificate, each line representing L1,L2,L3 ?

If this is right it seems straight forward enough, (I could imagine if testing a whole 3 phase board this would take forever though)

 

[TPES]

Ok.. this is the scenario..

There is a 10 way 3 phase sub mains panel, this is where the new 3 Phase circuit will be fed from..
This panel is currently feeding a number of other machinery and offices..

I wont be able to isolate this circuit due to the machines and offices running 24hrs in the factory.

This meaning there will be some readings i cant take when testing. Like Ze, PEFC.. Others?

And how do you get round this..??

 

[zupos40]

Ok.. this is the scenario..

There is a 10 way 3 phase sub mains panel, this is where the new 3 Phase circuit will be fed from..
This panel is currently feeding a number of other machinery and offices..

I wont be able to isolate this circuit due to the machines and offices running 24hrs in the factory.

This meaning there will be some readings i cant take when testing. Like Ze, PEFC.. Others?

And how do you get round this..??

So you can not isolate supply to measure Ze, did you measure Zs at the board before you installed the new 3 phase circuit, you can measure PEFC (as this is preformed with all earths in place) PSCC.

Also do they not have any shutdown for maintenace.

 

[Darkwood]

Ive never come across a firm that wont shut-down once ive expressed i cant issue a cert', its only for half an hour at most i,d only put 'testing limited' as a good reason if it was say a hospital and the board was the essential circuit supply backed by the generator.
Think your letting the customer guide you and not the other way round, what do they do in a power cut?

 

[TPES]

Thats right, i cant isolate the supply. There is no way for me to get to any incoming terminals without disconnecting circuits, (which i cant do) The board is an old rewireble 3 phase board. With isolator to the side of the panel, i cant take the cover off the isolator without switching the supply off.

I cant get to any of the incoming phases as there all concealed..

 

[Darkwood]

Thats right, i cant isolate the supply. There is no way for me to get to any incoming terminals without disconnecting circuits, (which i cant do) The board is an old rewireble 3 phase board. With isolator to the side of the panel, i cant take the cover off the isolator without switching the supply off.

I cant get to any of the incoming phases as there all concealed..

You may have write an additional note explaining this with your cert' but dont think it will absolve you if anything goes wrong, what if their is a low insulation resistance on this supply cable and the front end fuses are too big? the additional loading could create a fire. If power down is 2 or 3 hrs and a pain in the arse at least you tested it and got peace of mind.

 

[TPES]

I totally agree with you.
I think the factory would of lost alot more money with down time which is why they wouldn't of agreed on it.
I know this is no excuse for them as there saftey is main priority.

Is there any test i need to be carfull of when testing a sub mains as to not interfear with the main supply panel?