Powercuts (and shoddy workmanship)
Last night, we had a power cut. They are not uncommon here, but mostly happen during the afternoons or early evenings. Last night’s was a bit different though.
Sometimes in the past, we’ve been without power for several hours at a time. It’s not too big a deal though, since this apartment complex has several backup generators. Our generator is pretty much directly below the apartment next door, and is right next to where we park our motorcycle. It’s a massive thing – about the size of a small shipping container.
The generator doesn’t power the entire place though – it powers one fan and one light in each of the main rooms in each apartment. So, for us, that means one in each bedroom, and living room and dining room. There are no lights in the bathrooms, and none of the power sockets work. Well, that’s not strictly true – Gopal made a small modification to allow the socket the router is plugged into to draw power from the generator, so we can still have internet when the power is down. Nothing else works though.
When the power fails, the generator automatically starts up a couple of minutes later. It doesn’t automatically power those lights and fans though – we actually have to flip a switch in the living room to switch from mains power to generator power. When the power comes back on and the generator turns off, we lose power again and have to flip the switch back to mains power.
Last night, we got home just before midnight. I was sitting in the dining room in the dark, using my laptop, while Gopal was in the shower. After a few minutes, I noticed the internet had gone off and the bathroom light had gone out. Although the generator hadn’t started yet, I got up and walked into the living room and flipped the switch to switch to the generator in anticipation.
As soon as I flipped the switch, there was an explosion! The power supply for the router died with a big bang, some sparks and a big puff of smoke. I instantly flipped the switch back to mains and summoned Gopal out of the shower to find out what was wrong. We quickly realised it wasn’t a normal powercut since the generator still hadn’t come on, and then we peered outside and saw that the neighbours had their lights on and there were lights in the stairs and corridors.
We had a look at the fuse box – even pulling the covers off to check the wiring underneath, but nothing had tripped. Gopal went downstairs to the main supply cupboard and could smell that burned electrical smell which indicated that something had burned out in there. There wasn’t much else we could do at midnight, so we went to bed and called an electrician the next morning.
The electricity supply in most of India is different to our New Zealand domestic supply. It is the three phase system that most commercial buildings use. Instead of a single 240v live and a neutral, there are three 240v live lines plus the neutral. Each of the live lines (phases) is used to power part of the building. So you can have a partial powercut where one phase goes out and you (say) lose power in the kitchen only, while the rest of the house has power. The neutral is very important, because if you lose neutral, you lose all three circuits, even though all 3 phases are still live.
The electrician went to a central fuse box, saw that one circuit breaker for one of our phases had tripped, reset it and then said it was all fixed. Gopal knew that wasn’t the issue – if only one phase was out, we would have had power in some of the apartment, but we had none. He asked the electrician to come upstairs and check.
Up here, the electrician realised that we indeed had no power anywhere. He checked our fuse box but saw nothing had tripped. He asked for a stool and some tools so he could take the cover off to check the wiring. Gopal suggested he look downstairs first. He was a little reluctant but (probably thinking it was pointless) went down to the supply room.
He went in and opened the cable cupboard and it was on fire! It seems that the neutral wire hadn’t been connected properly, was loose and eventually started sparking, heating up the cables and causing a fire. At the point where we lost the neutral line altogether, we experienced the powercut, because the circuit was broken, although all of the phases in our apartment were still live. Eventually the insulation had burned away and the neutral made a short circuit with one of the phases. The main circuit breaker for that phase tripped on the control board at that time. Because there was still a (short) circuit completed in the cable cupboard, it kept generating heat and kept burning all night.
But why did the router power supply blow up when I switched to generator supply? Remember that we still had two live phases but with no neutral to complete the circuit. It seems that when I connected the generator, that completed the circuit through the generator, but with two phases instead of one. That meant that we had a circuit connected with some 480v. Luckily, all the lights and fans were off, and the only thing we had plugged into the generator circuit was the router. Not so lucky for the router of course, which instantly blew up. Anyway, since you are reading this online, we have by now obviously replaced/repaired the power supply and are back online. We do still need to make sure that the electrician actually does a proper repair job down in the cable cupboard, and doesn’t just leave it with the improvised temporary repair he did that morning to get our power restored. Otherwise the same thing is likely to happen again.