63A RCBO

stevetuk · Jul 25, 2025

I’m currently studying for my domestic electrician qualification and have a question regarding the attached image. The device is a 63ADP30BAT, a bidirectional double-pole RCBO.

From my understanding, "bidirectional" means I can connect the supply and load to either the top or bottom terminals. However, the RCBO has no markings to indicate which poles are Live or Neutral.

Based on the internal wiring diagram, it appears that both poles (1–2 and 3–4) include a magnetic trip coil and bimetallic strip. From this, I’ve concluded that either pole can be used for Live or Neutral, as long as the supply and load are correctly matched across each pole.

Could someone please confirm whether this interpretation is correct?

DefyG · Jul 25, 2025

It does look that way but I would double check with the supplier/manufacturer or stick to convention L-1 N-2.

mickegh · Jul 25, 2025

That whole damn subject about rcd/rcbo wiring was explained here to me and I've forgotten again

Wasn't the only problem that the test button wouldn't work on some wiring variations/models assuming you wire the poles correctly L-L N -N ?

westward10 · Jul 25, 2025

I would say it probably doesn't matter but as above I would use 1 for the live as that puts the test button switching the live but looking at other manufacturers some switch the test button through the neutral.

stevetuk · Jul 25, 2025

Thanks for your response. I understand that the standard procedure is to use the first pole for L, but I’m sure there are situations where this isn’t feasible, or else these products wouldn’t exist. My question was specifically about overcurrent protection on both poles and whether my interpretation of the wiring diagram is correct. Further reading suggests that the bimetallic strip and magnetic coil allow for LL 1 to 2 or LL 3 to 4 configurations. Either way, the circuit would be protected and trip in case of a short circuit, surge, or by using the test trip feature. Thanks again.

stevetuk · Jul 25, 2025

mickegh said:
That whole damn subject about rcd/rcbo wiring was explained here to me and I've forgotten again

Wasn't the only problem that the test button wouldn't work on some wiring variations/models assuming you wire the poles correctly L-L N -N

The location of protection is important. In most circuit diagrams, domestic RCBOs typically provide overcurrent protection only on the live wire, which, as I understand, is suitable for most scenarios (though a qualified professional could confirm this). In this case, the live (L) wire would need to be on the pole that is protected by overcurrent (normally 1). As someone mentioned L1, is generally considered a standard, though I'm not sure if it's an official standard or more of an industry norm. As long as the polarity is correct, everything should be fine.

plugsandsparks · Jul 25, 2025

See attached file (added by Dan)*

Says supply (grid) can go top or bottom, i would tend to use 1 for L and 3 for N

stevetuk · Jul 27, 2025

I understand that the RCBO supports supply connection at either the top or bottom terminals, as indicated by its bi-directional design. However, my question specifically concerns overcurrent protection on both poles. The internal schematic shows bimetallic strips and magnetic coils on both the poles (1–2 and 3–4), suggesting that either 1–2 or 3–4 can function as L or N. My query is not about the RCBO’s bidirectional capability, that aspect is clearly addressed in the datasheet, but rather whether full overcurrent protection is provided on both poles regardless of connection orientation, obviously maintaining polarity across the poles, L = 1 to 2 or 3 to 4. It doesn't matter which pole is used for L and it doesn't matter if load is top or bottom (bidirectional). Hope that makes sense.

westward10 · Jul 27, 2025

That would appear to be the case.

DefyG · Jul 27, 2025

The current flow through both poles should be equal, otherwise it will trip (assumed earth leakage) so it probably doesnt matter which pole the OC protection is on.

plugsandsparks · Jul 27, 2025

The diagram shows overload trip on both poles

mickegh · Jul 28, 2025

stevetuk said:
The location of protection is important. In most circuit diagrams, domestic RCBOs typically provide overcurrent protection only on the live wire, which, as I understand, is suitable for most scenarios (though a qualified professional could confirm this). In this case, the live (L) wire would need to be on the pole that is protected by overcurrent (normally 1). As someone mentioned L1, is generally considered a standard, though I'm not sure if it's an official standard or more of an industry norm. As long as the polarity is correct, everything should be fine.

Ya I forgot that there in my reply the pole mcb protection
I was probably thinking rcd

You've got to check everything in each circumstance is a good learning