Sweden cadmium electrical switch fire hazard

Other regulations: a number of years ago people in Sweden decided that cadmium was a toxic metal, and they wanted to ban it from the environment. There's about a tenth of a percent cadmium in the silver contacts in every light switch — that fifteen or twenty amp light switch on the wall, that you turn on the lights with — it's got a little bit of cadmium oxide in it. Because otherwise it would be a seven amp switch. Without a little bit of cadmium oxide you get arcs. With a little bit of cadmium oxide it suppresses the arcing, and you can get twenty amps out of that same silver contact. You go to the store and you buy this little cheap switch for $2 — you ought to buy the one for $10, the better quality one — but nonetheless, you can buy them. The Swedes decided cadmium's toxic. Well, the amount of cadmium vapor that comes off whenever you don't get an arc in a cadmium switch is so small that I don't think anyone in Sweden was dying. Someone could calculate some death rate from cadmium vapors. If you've got fifty million people in Sweden, I guess one person would die every thousand years. But within one or two years, they were burning down so many houses, they decided they could use cadmium. They reversed themselves.

1970s-80s Swedish environmental policy outlawed Cd in electrical components. Within three years, house fires from inadequate arc-suppression in <15A switches forced reversal. Teaching point: 0.1% CdO in Ag contacts raises arc-suppression rating from ~7A to 15A.

In Sweden, back in the 1970s or 80s, they're very environmentally conscious, and they decided to outlaw cadmium in the environment. The Scandinavians also wanted to outlaw chlorine in the environment. I don't know how you do that when you're surrounded by ocean. But they decided to outlaw cadmium, and they took the cadmium oxide out of their electrical switches. Within three years, they decided they would rather have cadmium oxide in their electrical switches than have people's houses burn down. They were burning down houses left and right.

Sweden outlawed cadmium ~30 years ago (i.e., ~1982 from a 2012 lecture). Light switches without cadmium oxide arc-suppression burned down houses; standard relaxed for electrical switches.

In part of the welding course I talk about cadmium and brazing. One time the Swedes outlawed cadmium in light switches. Every light switch — if I go flip the switch, I just created some cadmium vapor in this room, because that switch is a silver cadmium electrical contact. If you don't put the cadmium oxide in there it can only carry seven amps. That's a fifteen amp switch. The reason it can tolerate fifteen amps rather than seven is because the cadmium oxide suppresses the arc when you shut the thing off. You get some inductive effects — we don't have to go through what happens, but you could potentially get a little arc. If the arc lasts long enough it can melt the contacts together, and so you try to turn the switch off and it just welds itself together and stays on and starts fires.