We all have seen the cables hanging on poles along the street, and it looks like a total chaos for us, and dangerous as well. Surprisingly the danger doesn't really comes from this chaos, since there is order on the poles: Top level is high voltage, lower level is household electricity and the chaos comes actually from the telecom and internet companies.
But that doesn't mean electricity isn't scary here. It actually is. I am no expert and all and followed all my life the advise that you can fix a lot on things at home, but stay away from electricity. The problem is that most people here in Thailand actually think they are experts, and installation here seems to be more like an DIY way.
Today for example I plugged in the vacuum cleaner and suddenly the power socket was dead. I figured out all sockets upstairs are dead, but lights and aircon are just fine. Downstairs everything worked. Next step is then the breaker board. But all breakers were fine. I switched all off and on, but still the same problem. So I called the property management and they sent me the security (!) guard. He came with a screwdriver style neon tester - good idea, only we have safe sockets that require both pins to be stuck in at the same time to release a plastic protection. He didn't know.
So far I explained him the problem, he was also surprised the breaker didn't go off, and then we switched all breakers on and off and on and off. And... drumroll.. all sockets were live again. So he was smiling all over his face and didn't really understand why I was still concerned - power was back, work was done, let's have a nap.
But the scary part is still that the breaker didn't switch off when there was - what I think caused it - a power surge by the vacuum cleaner. That's why we have breakers. I will now replace all circuit breakers with new ones.
My neighbor has a similiar problem when he found out that he has a small current of DC where there should be none, and if it should be AC.
I remember that in Vietnam most fires in homes were caused by bad or faulty wiring, and in Laos it was quite the same. It was so scary that the advice was to call first the electricity department so they shut off the whole street - without that the firefighters wouldn't do anything.
There are some websites about what is a safe installation in Thailand. Siam Info has a good summary.
Thailand Guru has some information about grounding and earthing (by the way it seems that lightning rods are not really common here.
In case you are in trouble we found this website from Service Genie (haven't tried them yet), and they seem to know what they do. HomePro is also offering installation service and repair service. They did a pretty good job with deliver and installation of our washing machine. And you can always call the MEA (Metropolitan Electricity Authority)