RCCB - residual-current circuit breaker

[OneMoreFarang]

30 minutes ago, bankruatsteve said:

Interesting observation.  What do you mean by "too much leakage"?

The guy in the vides explains that a typical 30mA RCD interrupts the circuit at 24-25mA.

He explains that if you have a house with a couple of devices it is normal that some devices leak a little current. 1mA here and 2mA there and some more and it adds up and suddenly you are in the range where the RCD interrupts the circuit.

In the first video he tries to find a fault in a house with such a situation and he explains the problematic. 

[sometimewoodworker]

9 hours ago, bankruatsteve said:

Interesting observation.  What do you mean by "too much leakage"?

While not answering for OMF it is likely a reference to individual items having a small leakage current that when grouped exceed the RCCB’s limit so causing nuisance tripping.

[rcjoop]

A bit confused now, thought that since about 2016 use of RCBO is mandatory for the main switch with the subswitches often be non-RCBO. According to the video this would be problematic.

 

Was planning to replace the MCB in our house with a RCBO 50A Square D but hesitate now. Our house is not very big and the normal stuff connected, couple of aircons, 2 water heaters, fridge, waterpump etc nothing special.

The same I was thinking to do for the house of the daughter that also lacks a RCBO.

 

Would like comment from Crossy or one of the other pros if I would improve safety with the swap but get other problems in return, as we have had none in 15 years or that the swap is a good idea.

 

Thanks, Joop

 

[bankruatsteve]

45 minutes ago, rcjoop said:

Was planning to replace the MCB in our house with a RCBO 50A Square D but hesitate now.

That's probably the best way to go.  The downside is that you may (will) get nuisance trips when outside outlets/switches get wet or get critters inside.  You can easily re-set by turning off the MCB for the problem circuit and then find the culprit.  Another downside is if it trips when you are not there and the fridge/freezer stops running.  That is where some will put the single-pole RCBO on individual circuits and leave the main breaker as 2-pole MCB only.

[Muhendis]

41 minutes ago, rcjoop said:

A bit confused now, thought that since about 2016 use of RCBO is mandatory for the main switch with the subswitches often be non-RCBO. According to the video this would be problematic.

 

Was planning to replace the MCB in our house with a RCBO 50A Square D but hesitate now. Our house is not very big and the normal stuff connected, couple of aircons, 2 water heaters, fridge, waterpump etc nothing special.

The same I was thinking to do for the house of the daughter that also lacks a RCBO.

 

Would like comment from Crossy or one of the other pros if I would improve safety with the swap but get other problems in return, as we have had none in 15 years or that the swap is a good idea.

 

Thanks, Joop

 

I think it is not a good idea to use a whole house RCBO. The simple reason for that is, if something caused it to trip in the middle of the night, you would loose your lights too. 

[OneMoreFarang]

59 minutes ago, rcjoop said:

A bit confused now, thought that since about 2016 use of RCBO is mandatory for the main switch with the subswitches often be non-RCBO. According to the video this would be problematic.

 

Was planning to replace the MCB in our house with a RCBO 50A Square D but hesitate now. Our house is not very big and the normal stuff connected, couple of aircons, 2 water heaters, fridge, waterpump etc nothing special.

The same I was thinking to do for the house of the daughter that also lacks a RCBO.

 

Would like comment from Crossy or one of the other pros if I would improve safety with the swap but get other problems in return, as we have had none in 15 years or that the swap is a good idea.

 

Thanks, Joop

 

I also like to see a comment from @Crossy or other experts.

 

What you write above sounds like you have one MCB and you want to replace that with one RCBO, correct?

It would be a lot better if you would use several MCBs or several RCBOs.

Edited April 25, 2022 by OneMoreFarang

[OneMoreFarang]

6 minutes ago, Muhendis said:

I think it is not a good idea to use a whole house RCBO. The simple reason for that is, if something caused it to trip in the middle of the night, you would loose your lights too. 

That is the reason why many houses use multiple RCDs. To be sure that there is still electricity in part of the house. 

[OneMoreFarang]

10 minutes ago, bankruatsteve said:

That's probably the best way to go.  The downside is that you may (will) get nuisance trips when outside outlets/switches get wet or get critters inside.  You can easily re-set by turning off the MCB for the problem circuit and then find the culprit.  Another downside is if it trips when you are not there and the fridge/freezer stops running.  That is where some will put the single-pole RCBO on individual circuits and leave the main breaker as 2-pole MCB only.

Exactly that is explained in the first video which I linked above - for the people who prefer to watch.

[Crossy]

9 minutes ago, Muhendis said:

I think it is not a good idea to use a whole house RCBO. The simple reason for that is, if something caused it to trip in the middle of the night, you would loose your lights too. 

 

I agree.

 

But if you have nothing now and are on a limited buget ...

[Photoguy21]

30mA to trip sounds a bit high in a country where you are constantly perspiring 

[bankruatsteve]

22 minutes ago, Muhendis said:

I think it is not a good idea to use a whole house RCBO. The simple reason for that is, if something caused it to trip in the middle of the night, you would loose your lights too. 

Yah.  In my case, I just have RCBO on outside outlets and bathroom.  I could care less that light circuits have RCD protection and don't want it on fridge, pump, etc.

An upside to main breaker RCBO is not to worry about borrowed neutrals which can be difficult to find.

[Crossy]

10 minutes ago, Photoguy21 said:

30mA to trip sounds a bit high in a country where you are constantly perspiring 

 

10mA are available, but then you are into the realms of "tripping when you don't want it to".

 

In reality to 30,30,30 rule (30V, 30mA, 30ms) is arbitrary anyway and is non-lethal to 95% of healthy adults, the elderly, very young or infirm are much more suseptable to death by shock.

 

By far the best defence is the prevent the possibility of shock by good grounding, MEN implementation and proper design, the RCD/RCBO should be your second line of defence.

[Photoguy21]

5 minutes ago, Crossy said:

 

10mA are available, but then you are into the realms of "tripping when you don't want it to".

 

In reality to 30,30,30 rule (30V, 30mA, 30ms) is arbitrary anyway and is non-lethal to 95% of healthy adults, the elderly, very young or infirm are much more suseptable to death by shock.

 

By far the best defence is the prevent the possibility of shock by good grounding, MEN implementation and proper design, the RCD/RCBO should be your second line of defence.

A leakage of 30mA is a lot really. I set mine to 20mA and never had it trip

[Crossy]

8 minutes ago, Photoguy21 said:

A leakage of 30mA is a lot really. I set mine to 20mA and never had it trip

 

30mA is an international standard for 230V countries chosen as a happy medium between not killing most people and not tripping at those inconvenient times (like when you're away and didn't put your freezer on an un-protected outlet).

 

Actually, a 30mA unit will trip anywhere between 15mA and 30mA, it doesn't take many PCs leaking via their mains filters to get into the tripping risk zone.

 

If you have an adjustable unit there's no reason not to set it as low as it will go without going off when you don't want it to.

 

It's worth noting that the RCD/RCBO doesn't actually limit the shock current, that's determined by your body resistance, it just (hopefully) disconnects the supply before you die (the 30ms) if it detects MORE than 30mA going where it shouldn't.