2391 Practical

[danielspencer]

Hi

I've got my 2391 practical this week. The only thing I'm not 100% about is the simulated insulation resistance tests. If you get a reading 0.00Megohms on the 500v test, they want you to switch to the continuity range and take a low-ohms reading and record this.

The problem is, nobody could seem to agree at what measurement in ohms do you decide between a short circuit and a low resistance fault.

Another thing with regard to Safe Isolation at the start. The main switch on the test rig does not have terminals at the top to test for dead, IR testing etc.
I don't really want to have to remove the busbar cover. The instructor was making a pig's ear of trying to stick his voltage indicator into the busbar side of the motor circuit breaker. Would it be acceptable to turn the main switch off, remove the cover, lock-off the main switch, switch the 3 phase motor circuit breaker on and test for dead at that side of the breaker L1+L2, L1+L3 etc...?

Do they expect you to remove and inspect every socket on the ring?

Any advice would be appreciated.

Many thanks.

 

[xraytek]

When I did this exam the practical a couple of years ago it consisted of 3 small assessments (30mins allowed for each) and 1 assessment that took 1.5hrs.
The 3 small assessments were visual inspection, insulation test, and EFLI test.

The visual was to spot about 20 mistakes on a rig and took just a few minutes.

The insulation test was a sealed CU with bare tails out of the bottom. You had to test across the tails and determine which circuit had a fault, and between which conductors.
On my assessment you only had use of an insulation tester but I suppose it wouldnt hurt to use a continuity test to obtain the exact measurement. I wasnt asked to determine between a load or a fault, only to identify the faulty circuit.

The EFLI test was test taken from a socket, and I was given a senario of the rating of protective device. I then determined ( using rule of thumb) whether the reading was ok or not.

The 1.5Hr assessment was a PIR on a 3 phase DB that also fed a single phase sub main. The whole rig was isolated using a rotary switch that fed the main switch. This rig was not the same one we trained on as I dont think you are allowed to see it before the exam.