Megger MFT1553 unusual readings while testing rcbo's

[leebut]

Hi Guys

I'm fresh to the EF had a bit of a bad day, replaced an old wylex Bs3036 consumer unit with a new enclosure with 8 Rcbo's (1 x 40, 4 x 32,1 x 20, 2 x 10 amp) all went in fine all continuity, end to end tests and insulation tests went well, until I started testing the rcbo's using the auto rcd test on my MFT1553 all eight circuits tested the half load fine (>1999) but as soon as test two started the Megger gave me a reult of 400ms and wouldnt test any further.

I then tried testing all eight circuits again manually, on 1 x it's result were 400ms, then at 5 x the result was 40ms both tests did not trip the Rcbo's i then carried out a ramp test on all the circuits they all tested at 51ma, I have tried brand new batteries but I'm getting the same results, I took the tester home and tried it again on my house with exactly the same results, has anyone had the same problems and how did you get the tester back on track??


many thanks

Lee

 

[Sintra]

We're you testing at the RCBO or an outlet? What make are the RCBO's?

 

[leebut]

i was testing at the Rcbo's but i even tried testing a socket outlet both onsite and at home all with the same results


lee

 

[Marcusdmullins]

How many leads were you using to perform the test and where were you testing at? DB or outlets?

 

[leebut]

i was initially using the two leads directly onto the Rcbo's at the DB then tried testing at socket outlets with same results


lee

 

[skydog23]

Mite be a dumb answer, but wot conditions are the batteries in ?
Low batteries can throw up spurious readings on all testers.

 

[skydog23]

The new batteries that is

 

[leebut]

Put brand new batteries in and still same results


lee

 

[MarkF]

Hi Lee,

I've had a quick word with one of our engineers in our service department, if your tester is doing the same thing on different circuits, it's possible it's not putting the test current into the circuit and the unit is simply timing out - the unit should be returned for investigation. These models carried a 3 year warranty, so depending on the age, it may still be covered.

 

[leebut]

Hello mark f

Thanks for the message regarding sending my tester back for checking its a big mystery to me

Lee

 

[telectrix]

try borrowing a set of leads and try the megger again.

 

[tony mc]

When you turn on your tester look at the screen it will briefly show a code then it will flash up with your battery voltage. New batteries should show more than 12 volts on the screen! On the 1 x and half I would of said you had the blue scale set at 10 mA but putting 50mA in on the 5 x should of tripped the RCD. The 51 mA ramp also says something about your meter I take it the RCBO did trip. Let us know how you get on !

 

[Kate]

I have this tester, batteries are not great in it. I it reads 9.? Or less I get funny results all the time. Have learnt to carry spare batteries at all times. I have never had trouble testing rcbos though. This definitely sounds like u need to send it back and be checked.

 

[oldtimer]

Did I miss something here what make are the RCBO,s

 

[tony mc]

Good point and where did you buy them especially when the market seems to be getting more & more fakes. If he is getting the same results at his house then the meter has be to a good bet !