Circuit Breaker needed for Split Air-con with Inverter

Johnny Swails · Mar 31, 2019

Hello all. I´m installing a new multi split Air Conditioning (Inverter Type) in my dwelling and I have to purchase all of the electrical parts needed for the installer. I am currently running a 63a Type-A RCCB and I was told by the electrician that I could use the Type-A with a 16a Type-C MCB but according to my research, I need to upgrade to a Type-B RCCB. Does anyone have any experience in this?

Johnny Swails · Mar 31, 2019

In short, we don't want to replace the RCCB with a Type-B because of cost if it's possible

Johnny Swails · Mar 31, 2019

In short, we don't want to replace the RCCB with a Type-B because of cost if it's possible

plugsandsparks · Mar 31, 2019

FWIW, never had to install a Type B yet for these small units. The larger ones dont yet command RCD protection.... suspect that may change.......
The leakage currents are very very small and the more modern the unit the less impact they are having on supply harmonics. I would expect the latest Daikin baby unit to be more than happy on a type A.
UNLESS Daikin STATE IT MUST BE A TYPE B

plugsandsparks · Mar 31, 2019

Just a thought though. A/C units do leak to earth, even if its a small amount. I do remember one flat i went to that had 3 large units all fed off one up front RCCB, they were experiencing random tripping. Once i added all the leakage from the AV equipment they had as well as the a/c, there was no wonder it was tripping as the combined leakage of the whole flat was well above 15mA, cannot remember how far over it was but i simply put each a.c unit on a separte RCBO.....

Johnny Swails · Apr 1, 2019

plugsandsparks said:
Agree with C16 either MCB or RCBO depending on whats up front. This system looks like a 2 room multi-split with both rooms indoor units powered from a 3C+ earth direct to outdoor unit. I personally do not use indoor local isolation as there is little point, you still need to isolate the compressor before working on it. So i cable direct using YY cable. Daikin are the Daddy, R32 gas is the new stuff bit more flammable than R410A so have it serviced regularly.. .....

It's a 2 room multi 2.5kw for bedroom and 3.5kw for living room. I ran a 4x1.5 between both indoor units to outdoor. I ran all cable through cable canal and piping canals

plugsandsparks said:
Just a thought though. A/C units do leak to earth, even if its a small amount. I do remember one flat i went to that had 3 large units all fed off one up front RCCB, they were experiencing random tripping. Once i added all the leakage from the AV equipment they had as well as the a/c, there was no wonder it was tripping as the combined leakage of the whole flat was well above 15mA, cannot remember how far over it was but i simply put each a.c unit on a separte RCBO.....

Thanks for the reply. As I said before, I am no electrician. My father is, and I worked with him many of summers in his company but he´s in America and the US has a completely different system. I also wasn´t allowed to do any work in the breaker box and for good reason. With that said, I have a "decent" understanding of running wires, connections, GFCI´s, etc..I however don´t completely understand everything in the box. This is exactly what Daikin gives in the manual. It´s quite vague. Nowhere does it specificly state that it must be a Type-B but according to my research, it would need a Type-B because of the inverter. We also do have several computers if that does play a role.

[ElectriciansForums.net] Circuit Breaker needed for Split Air-con with Inverter

Johnny Swails · Apr 1, 2019

My electrician friend here said that he would recommend leaving the Type-A and just installing a C16 for the unit. Any thoughts? Or would I be better with a RCBO "x"16? Would the RCBO be run off of/in sequence with the RCCB or would that cause problems?

plugsandsparks · Apr 1, 2019

Valid options are: C16 MCB leave RCCB in place as electrician suggests, possible outcome too much leakage overall, however, this is a small chance. I have two outdoor units off a RCCB in Spain but there's just a TV, Sat receiver and laptop.
2nd option C16 RCBO, this will need the board to be re-jigged and may not be physically possible if the board is old and not designed for RCBO's. / not enough room for a common isolator if there is not one already.
I would go with your electricians suggestion as if it does not work, he will be the one to figure out why.

Deleted member 105166 · Apr 1, 2019

Johnny Swails said:
My electrician friend here said that he would recommend leaving the Type-A and just installing a C16 for the unit. Any thoughts? Or would I be better with a RCBO "x"16? Would the RCBO be run off of/in sequence with the RCCB or would that cause problems?

Where an upstream device is rated similar to the RCBO, there will be no selectivity therefore won't prevent nuisance tripping.

Johnny Swails · Apr 1, 2019

plugsandsparks said:
Valid options are: C16 MCB leave RCCB in place as electrician suggests, possible outcome too much leakage overall, however, this is a small chance. I have two outdoor units off a RCCB in Spain but there's just a TV, Sat receiver and laptop.
2nd option C16 RCBO, this will need the board to be re-jigged and may not be physically possible if the board is old and not designed for RCBO's. / not enough room for a common isolator if there is not one already.
I would go with your electricians suggestion as if it does not work, he will be the one to figure out why.

Thanks. I believe we will start there. In any case, we would still need to install the c16. We can always get a Type-B RCCB later and install if needed.