blookhead57 Posted January 30, 2018 Share Posted January 30, 2018 RCBO (residual currant circuit breakers ) yes is the best way to go but expensive one can cost as much as one RCD its a Rolls Royce job. Incidentally if you don't know RCBOs are circuit breakers with RCD built into them so every circuit has its own RCD on it so if the circuit trips because of earth fault then you don't loose all the installation just that circuit and you leave the main switch there or in your case the double pole circuit breaker. I would think that maybe you may have problems getting RCBO in Thailand because of the cost. Thai like everything done on the cheap so nobody would buy them plus the fact some of them probably don't know what they are. Supply and demand. Link to comment Share on other sites More sharing options...
Crossy Posted January 30, 2018 Share Posted January 30, 2018 @blookhead57 VERY IMPORTANT You can not apply UK standards here. There is no DNO fuse in a Thai domestic installation, the front end MUST be an MCB, MCCB (in 3-phase installations) or RCBO. A simple Main Switch or RCD like we would use in the UK is not suitable as there will then be no over-current protection for the incoming supply. A short in the CU will result in an event of an explosive nature, not to mention what would happen to the poor 50A meter. This document (225 Baht) https://eitstandard.com/มาตรฐานการติดตั้งทางไฟ-2/ and the others in it's family will tell you all you need to know about Thai electrical installation. Failing that AS3000 (Aussie standard) is close enough for domestic work. In our OP's CU the earth bar is indeed connected to the incoming neutral so all is well. The Thai implementation of MEN (PME) requires a local earth rod at least 1.8m long (not sure what an "earth steak" is), which is something our OP needs to verify. Schneider / Square-D plug-in 2-pole RCBOs which will directly replace the incomer are available here, I have the catalog somewhere but try a forum search. Link to comment Share on other sites More sharing options...
blookhead57 Posted January 31, 2018 Share Posted January 31, 2018 (edited) 2 hours ago, Crossy said: @blookhead57 VERY IMPORTANT You can not apply UK standards here. There is no DNO fuse in a Thai domestic installation, the front end MUST be an MCB, MCCB (in 3-phase installations) or RCBO. A simple Main Switch or RCD like we would use in the UK is not suitable as there will then be no over-current protection for the incoming supply. A short in the CU will result in an event of an explosive nature, not to mention what would happen to the poor 50A meter. This document (225 Baht) https://eitstandard.com/มาตรฐานการติดตั้งทางไฟ-2/ and the others in it's family will tell you all you need to know about Thai electrical installation. Failing that AS3000 (Aussie standard) is close enough for domestic work. In our OP's CU the earth bar is indeed connected to the incoming neutral so all is well. The Thai implementation of MEN (PME) requires a local earth rod at least 1.8m long (not sure what an "earth steak" is), which is something our OP needs to verify. Schneider / Square-D plug-in 2-pole RCBOs which will directly replace the incomer are available here, I have the catalog somewhere but try Ok an earth steak is the same as a earth rod (English term) incidentally what's a DNO fuse? Ok this Gent then cant remove the main switch circuit breaker he will have to fit an external RCD. I don't think you can get a double pole 63A RCCBO plug in breaker. Edited January 31, 2018 by blookhead57 Link to comment Share on other sites More sharing options...
Crossy Posted January 31, 2018 Share Posted January 31, 2018 31 minutes ago, blookhead57 said: Ok an earth steak is the same as a earth rod (English term) incidentally what's a DNO fuse? Ok this Gent then cant remove the main switch circuit breaker he will have to fit an external RCD I was being facetious, the word is "stake". Anyway, the DNO (Distribution Network Operator https://en.wikipedia.org/wiki/Distribution_network_operator ) fuse is the 80A (or so) BS88 fuse that is found in the service head where the supply enters the property. Thailand does not have these, over current protection for the supply is provided by the MCB in the CU. Our OP CAN replace the current 2-pole MCB (overload only) with a 2-pole RCBO (earth leakage plus overload), he cannot replace it with an RCD (earth leakage only). One of these, yes I know that's a 50A unit, but since he's likely on a 15/45 meter that's actually the right one. ;- EDIT Here's the 63A one https://www.lazada.co.th/2p-rcbo-63a-34schneider34-77047448.html still shows the picture of the 50A. Lazada have them https://www.lazada.co.th/2-50-rcbo-2p50a-30ma-10kaschneidersquare-d-23017589.html Link to comment Share on other sites More sharing options...
blookhead57 Posted January 31, 2018 Share Posted January 31, 2018 11 minutes ago, Crossy said: I was being facetious, the word is "stake". Anyway, the DNO (Distribution Network Operator https://en.wikipedia.org/wiki/Distribution_network_operator ) fuse is the 80A (or so) BS88 fuse that is found in the service head where the supply enters the property. Thailand does not have these, over current protection for the supply is provided by the MCB in the CU. Our OP CAN replace the current 2-pole MCB (overload only) with a 2-pole RCBO (earth leakage plus overload), he cannot replace it with an RCD (earth leakage only). One of these, yes I know that's a 50A unit, but since he's likely on a 15/45 meter that's actually the right one. ;- EDIT Here's the 63A one https://www.lazada.co.th/2p-rcbo-63a-34schneider34-77047448.html still shows the picture of the 50A. Lazada have them https://www.lazada.co.th/2-50-rcbo-2p50a-30ma-10kaschneidersquare-d-23017589.html ok very good this is what this gent needs I noticed its only 10KA I hope his not near the transformer where it might have short circuit potential of more than 10,000 amps. Incidentally I use to be dyslexic but I couldn't spell it LOL. Link to comment Share on other sites More sharing options...
Crossy Posted January 31, 2018 Share Posted January 31, 2018 Yeah, 10kA should be fine. We are only 150m from the village transformer our PFC is 500A (source impedance is around 0.5 ohms). Yes, we get pretty bad voltage droop on load, hence my thread on installing an AVR. As a southpaw I too suffer from word blindness (although it's much better now than it was at school), can be an issue as an engineer. Link to comment Share on other sites More sharing options...
blookhead57 Posted January 31, 2018 Share Posted January 31, 2018 4 minutes ago, Crossy said: Yeah, 10kA should be fine. We are only 150m from the village transformer our PFC is 500A (source impedance is around 0.5 ohms). Yes, we get pretty bad voltage droop on load, hence my thread on installing an AVR. As a southpaw I too suffer from word blindness (although it's much better now than it was at school), can be an issue as an engineer. a lot of intelligent people are dyslexic Link to comment Share on other sites More sharing options...
Crossy Posted January 31, 2018 Share Posted January 31, 2018 7 minutes ago, blookhead57 said: a lot of intelligent people are dyslexic Absolutely, a lot of famous names on this list https://www.thefamouspeople.com/dyslexia.php and significant commonality with this list https://www.thefamouspeople.com/left-handed.php You a leftie too? Link to comment Share on other sites More sharing options...
blookhead57 Posted January 31, 2018 Share Posted January 31, 2018 10 hours ago, Crossy said: Absolutely, a lot of famous names on this list https://www.thefamouspeople.com/dyslexia.php and significant commonality with this list https://www.thefamouspeople.com/left-handed.php You a leftie too? no just dyslexic I took a test on line and realised I was but it was never recognised at school Link to comment Share on other sites More sharing options...
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