Testing on RCCB boads

[Hammyboy]

Im doing a lot of testing the now but need a bit of guidance.

In the place that im workin has RCCB boards (i take it they are the same as RCD boards?) Is ok to do testing on them Insulation resisatnce etc??

I also set my testing equipment to 'no trip' on the ZS test but most of the time the breaker trips any ideas why that might be??

I would also like to know - there is a distribution board with time clocks on it is ok to test them?

cheers

 

[SparkyNinja]

Errr ok,

Have you done much testing before?

What kit are you using?

 

[Hammyboy]

Errr ok,

Have you done much testing before?

What kit are you using?

Only some, mostly worked on large sites though.

Im using a MEGGER MFT1553.

Just need some refreshing mate

 

[Spark123]

An RCCB is a type of RCD - RCD is a generic term covering a whole range of devices.
As for wether or not you can IR test depends on the type of RCD - usually electronic ones don't like 500v shoved up them. These usually have a functional earth wire attached or are in the form of a socket with integral RCD. They normally come with a sticker to put on the fuse box to tell you not to IR them.
Doing a full load Zs will send 23A down the earth so there will be an imballance, luckily for you there is a low current setting on the MFT 1553 so you can do Zs without tripping the RCDs - you'll need to use all 3 wires for this and if the supply is too noisy the MFT kicks up a fuss! I also tend to find the readings come out a bit higher than doing it the old way.

 

[JACKC]

Didn't the Megger MFT have a fault on the no trip setting, how old is your MFT, it may be worth contacting them as they carry out a mod FOC.

 

[Hammyboy]

Didn't the Megger MFT have a fault on the no trip setting, how old is your MFT, it may be worth contacting them as they carry out a mod FOC.

Ive been using the no trip setting and in most cases when testing at the RCCB it has been tripping.

Im not sure how old it is mate.

 

[Spark123]

You can measure Zs by adding your R1+R2 value to the Ze (or Zbd if it isn't at the source)
You may need to short out the RCD to do the R1+R2 test as I have found they have a tendancy to trip when 200mA is pushed through them with a MFT on continuity, but as a dead test is fine to do this.
I wouldn't recommend shorting out an RCD to do the test live though.