Any tips on the C&G 2330, 303 practical exam?

[schmeagle]

Hello all members of the DIY not forum.
Was wondering if anyone has done their 303 practical exam yet and if they might have any tips that they might like to share? I have got my exam coming up in a week and even though I know how to test it would be an advantage to know roughly the types of faults that may occur and the order in how to find them with the results found i.e. IR = 0MὨ (short circuit), how can you tell were the short circuit is without the visual inspection (removing the trunking lids etc and looking for the faults).
Any help would be grateful and thank you in advance to any posts.

 

[bernardgreen]

Being pedantic if the IR = 0 ohms then the fault is where your probes are touching the conductors. You can work out where the short is by accurately measuring the resistance and then using the value of ohms per metre for the cable then work out the approximate distance to the short circuit.

There are more accurate methods but I doubt these are ever taught for testing purposes. ( testing as apposed to fault finding )

This method puts a current through the cable to generate a voltage drop along the cable. The ratio of voltages gives the ratio of distances and does not require highly accurate ohms readings which are seldom possible with the variations in contact between probes and conductors

Untitled

• bernardgreen
• 8 Feb 2011
• 3

 

[schmeagle]

Nice answer burnardgreen, any chance you could add an example by any chance on the formulae that you would use? Don’t think I will need this information for the exam but I am interested for understanding it personally?