individual RCBOs or a main breaker RCBO? and what trip level 10mA or 30mA

[peter le grand]

I have the feeling that I might have small currents running in the house. So first of all, I am considering to get a leakage clamp meter. But besides of this, I am also considering to replace the breakers with RCBO. But then the question, should I go for indivdual rcbo or just replace the main breaker with an rcbo? and if I replace individual rcbo should I go for 10mA or 30mA? I have the feeling it should be 10mA as in general, you want to do something about if there is 10mA and tripping does is the correct thing to happen.

any suggestions?

 

[littlespark]

The standard in the Uk domestic is 30mA.

Individual RCBO per circuit is preferred just to avoid nuisance tripping.


If you think that every device or piece of equipment carries a tiny tiny element of earth leakage… nothing that would individually trip even a 10mA… but all added up, could do.

So a 30mA as a main switch covering all circuits is sensing an accumulation of everything plugged in and connected… not necessarily
switched on.
If that tripped, everything would be turned off, it would be more difficult to find the fault.



What makes you think you have a fault?

 

[MDJ]

I have the feeling it should be 10mA as in general,

any suggestions?

Think again


Get a spark in

 

[littlespark]

Maybe 10mA is a standard size in Thailand??

but it wont be much use as main protection for all circuits. Maybe one circuit or even just one appliance.

30mA gives a little more leeway, but if there's a known fault.... its just going to trip.

 

[pc1966]

In general an RCBO board is a much better choice, if there is a fault your impact is limited to only the faulted circuit and not others off the same RCD.

As for 10mA versus 30mA that will come down to local regulations. What you have to remember is the RCD side dose not limit current, it limits time above the current. That is a very different aspect! So 10mA and 30mA RCD will hurt just the same, what would reduce that pain & risk is quicker tripping times.

What 10mA trip gives you is less chance of being in the narrow window of "can't let go" to "RCD trips" but in reality most unfortunate encounters with an RCD has a bit more current as you grip tighter and either type will go fast. If working!

Test your RCD, and test them regularly (6 months etc)!

 

[littlespark]

the 10mA and 30mA are the differences between line and neutral. if they arent equal, then that current must be leaking to earth... which may or may not be through a persons body.

the limiting factor is how quickly they are supposed to trip off.... in UK, its 40ms... but thats a limit... they normally trip way before that.

 

[peter le grand]

Thanks for all the advice. The reason I am looking at this is just to improve my electric system. I found various issues and see various reasons why this might be a problem. I will do a separate post on some of them. But some water pipes I have the feeling have some charge. Further, there are some strange voltage measures on the ground cable at some point. And I have ghost lights.

There are actually no regulations here. Also for residential there are not really certified electricians. they work for industries.

 

[Harmet]

Ground the water pipes.

 

[Teddy Lop]

In general an RCBO board is a much better choice, if there is a fault your impact is limited to only the faulted circuit and not others off the same RCD.

As for 10mA versus 30mA that will come down to local regulations. What you have to remember is the RCD side dose not limit current, it limits time above the current. That is a very different aspect! So 10mA and 30mA RCD will hurt just the same, what would reduce that pain & risk is quicker tripping times.

What 10mA trip gives you is less chance of being in the narrow window of "can't let go" to "RCD trips" but in reality most unfortunate encounters with an RCD has a bit more current as you grip tighter and either type will go fast. If working!

Test your RCD, and test them regularly (6 months etc)!

Sort of; technically speaking the 10mA is required to hit the 40mS target at 50-149mA, whereas the 30mA device can be happily snoozing along for it's 300mS alarm call. Of course in reality they tend to all meet the 40mS time whatever the fault current.

10mA pointless for general use though, a hospital thought they were being mostest cleverest and had them fitted, ended up ripping them all out due to excessive nuisance tripping. Also the American embassy specified 10mA RCD sockets in the kitchen on a house rented for a diplomat. Besides that I don't think I've ever seen one, not in the city anyway!