Why you need a Tav Teken

I recently bought an electrical splitter from a local hardware store. I specifically wanted a cordless one, and one with the maximum possible number of outlets. Usually you only get up to three points on a cordless splitter, so I was very happy to find one with four points.

But hold on a second. My electrical engineering instincts told me that something was amiss. Didn't I once encounter one of these splitters before, many years ago, in the context of a minor electrical explosion? Well, let's open this baby up and see what sordid sins are hiding behind that clean facade...

Have you spotted the problem? Let me enlarge and annotate this second picture for you...

Well, the earth (green) looks OK. Now take a look at the live circuit (brown). As you face the socket, live should be on the right. And on the right had side of the splitter, the right hand socket is brown. But look at the left hand side: the positions of the live and neutral points have been reversed!

I took it back to the store and got a refund. I showed this faulty wiring to the shop attendant, who assured me that it's perfectly OK to switch around the live and neutral points; it makes no difference which side they're on - and he promptly put this michshol straight back on the shelf.

I presented him with my credentials as an electrical engineer (sort of true - I got the degree then went to work in programming), and attempted to explain that while it may be OK to switch the live and neutral for your unearthed radio/tape player, the minute you plug in an appliance that needs to be earthed, you are going to create a moderately large explosion. The earth and the neutral need to be at the same voltage (or close), while the live oscillates between about +330V and -330V, creating a Root Mean Square voltage of about 220V. (Wow! I remembered that from university, 15 years ago!) If you start sending oscillating voltages up your neutral wire where there's an earth connected, you are going to create a big, fat 220V short-circuit into your earth. That makes a nice big spark, possibly destroying the appliance you were unfortunate enough to plug into this socket.

Yeah, yeah. Whatever. And the splitter stayed on the shelf for the next unwitting victim.

If I'd had more time, I would have been more forceful. Perhaps I should have been, anyway - this may be a case of hashovas aveida, to prevent damage to anyone else who might buy one of these nasty little jobbies.

Anyway, the moral of the story is: make sure that when you buy electrical stuff, it should have the tav teken. Otherwise there is no guarantee that what you bought is anything better than seriously dangerous.