Another Rcbo Discussion

[Ticketmaster]

I am currently at the stage of choosing circuit breakers for a new house. There have been past discussions on this board about using RCBO’s on instant water heater (shower) circuits. The sparkies that have weighed in seem to also advocate this. But since these devices are already equipped with ELCB’s, it seems like an unnecessary redundancy. Sure we want to maximize safety, but given serious expense, there are limits. Any advice?

Second, when I left the US several years ago, the only residential [they called them GFI’s ground fault interrupt devices] required by code were for electrical outlets in bathrooms and out of doors. Using these devices on lighting circuits or other electrical outlets was unheard of. Yet on this forum, there seems to be strong advocacy
for using RCBO’s everywhere. What’s the score on this?

One could use an RCBO main breaker and cover many circuits, saving a ton of money, but since RCBO’sometimes trip for mysterious reasons (always a scientific reason, but often difficult to determine), using an RCBO as a main covering multiple circuits would make trouble shooting mysterious trips exceedingly difficult, so I will stray away from them.

[selftaopath]

I fear the water heaters typically used in Thailand. Therefore I opted for a water heater which uses LPG and only has a AA battery to turn it on/off. I feel much relief. The idea of having an electric device in the shower area scares the hell outta me.

[Crossy]

The built in RCD devices in water heaters only offer protection from internal failures. Backing up with a unit in the board provides protection for the cable running to the heater.

Many countries electrical regulations now advocate RCD protection on ALL circuits in a domestic environment (UK and Aus specifically). As a minimum you should protect all outlets with some form of RCD, maybe not the one for the freezer but certainly everything else.

One further point to consider. When in Thailand you're likely to be barefoot and damp (ok sweaty) on a concrete floor, your hands will also likely be damper than they would back home. All this lowers your bodys electrical resistance, which, coupled with the higher supply voltage than the US, will make any shock you receive more hazardous.

RCDs and RCBOs are not expensive compared to a life.

To minimise costs, reduce inconvenience from nuisance trips and still provide protection, consider a split-service board like the one on this page http://www.crossy.co.uk/wiring/Consumer.html

[bankruatsteve]

I put the shower unit (with ELCB) on an RCBO only b/c I also put a bath outlet and a few outside outlets on the same circuit. Otherwise, I think the ELCB is adequate and if the electrical connections are inside the unit.

I can't find any meaningful statistics on RCD protection vs. not and, as stated, an RCBO is not much compared to a life, but would a life be lost without one? Who knows?

Another difference for Thailand compared to the states is that grounded appliances (tools, etc.) are very rare.

[Crossy]

Another difference for Thailand compared to the states is that grounded appliances (tools, etc.) are very rare.

Class-I appliances with the ground not connected (rather than Class-II which don't need a ground) are very common here.

Number one reason to have an RCD / RCBO

[lopburi3]

As said above the RCBO within the shower unit only protects on the down side of that unit (if that - yes I have has a mechanical failure of a name brand unit where the test shaft stuck and prevented the breaker from tripping). At least you are alive working to find the trip cause rather than DOA. Having used for full house more than 35 years do not believe the handful of times I have had to search for fault to be excessive - and on one occasion it was inside a wall outlet so not easy to find.