Problem with Ze test

[maclellan0141]

Hello There! I'm relatively new to testing (the last time I held a test instrument was for my trade test 2 and a half years ago.) But luckily, I kept most of my papers from college and they have been very helpful.

I started A new job last week that involves alot of testing. I'v picked up most of it pretty well but I seem to be having a problem when I carry out my Ze test.

For the record, I work in a warehouse that tests site cabins before they are delivered to a job. My boss told me to not bother with doing a Ze test. I assume this is because the Ze at the warehouse will have no relevance to whatever site the cabins end up at. But I'd still like to do it anyway just for myself so I know what I'm doing in future jobs.

I'm isolating the CU at the cabin, disconnecting the main incoming earth and testing between there and the incoming line. When I press the test button it comes up saying 'trp' on the multi-meter and voila, the RCD at the db feeding the cabin has tripped. Am I doing something wrong?

The kit I'm using is a Meggar MFT1720. There are 2 knobs on it. The left knob is being set to 'L-PE' and the right knob is being set to 'Max Z'

Thanks in advance, any responses will be appreciated.

 

[telectrix]

this is because you are trying to do a high current EFLI test with an upstream RCD. that's why it trips. basically, they don't like it up 'em mr. mainwaring.

 

[trev]

I agree with your boss that the test is a waste of time and effort but can understand you wanting to do it just to get it into your head. Does your meter have a no trip function? It's sometimes called D-lock.
Obviously I'm not familiar with the one you're using

 

[maclellan0141]

I'm looking at it now and can't see a no trip function on it. There are 4 settings under the 'Loop' part of the dial. Z, Max Z, Z ref and R1+R2. Do any of them sound right to you? If not it's no big deal. I guess I'll just have to bite the bullet and ask the boss.

 

[maclellan0141]

Thanks for the shout!

 

[trypod]

What is the firmware version?

On the firmware versions V1.08 or lower you may have to change the leads around to stop it tripping the RCD

What make is the RCD?

 

[maclellan0141]

Sorry man I'm not sure about either of your questions. I'll have a look when I'm on the job tomorrow. If I haven't figured it out what i'm doing wrong, I'll report back here...

 

[applemac]

its all confusing with the new firmware, on L-PE you get only to options 3 lead low current or 2 lead hi current i think..

 

[maclellan0141]

Yeah thats right I think. I'v been using the 2 lead hi option. Do you think this might be the problem? I guess the 3 lead low option is connecting the 3rd lead to the incoming neutral? What is the differance between the 2?

 

[applemac]

should just be a 2 lead test, 1 one the main earth disconnected from met or earth bar, one on the incomer at the main db
if your testing at a sub board fed from a rcd it will trip as its up river n all...

 

[maclellan0141]

Ah cool. Thanks for that mate. big help.