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In my kitchen I have some cabinets with 10w, 12v halogen bulbs (i have no idea what those numbers mean, I'm just reading it out as its marked on the bulbs - all I generally know is higher the watts - the brighter the bulb :) ) and they are G4 socket... when pulling one of the bulbs out, one of their "prongs" kind of broke, so I shut down the mains and slowly pulled it out of the socket with some pliars.

Now I am curious, had I not shut down the mains before pulling out that broken prong, could I have gotten a shock?

I am in Europe (220v unlike the US' 110v)

Mag1cboy
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  • If you know what you are doing, then shutting off power is not necessary. I've seen wall outlets replaced while power was still live, and This Old House on TV once had live power from the street connected to a house panel. But that is not safe practice for most people. Be safe rather than sorry (or dead). At worst you spent a little extra time shutting off power and then resetting some clocks. – sawdust Oct 20 '14 at 00:55

3 Answers3

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No, you cannot get a shock from 12 volts, so there is no need to switch off the mains.

However, do remember that the 12V bulb is connected to a transformer which converts the 220V mains into the 12V needed by the bulb. This means that lethal voltages are present at the other end of the transformer. This transformer may be installed right behind the bulb (inside the lamp fitting), or it may be some distance away inside the wall or ceiling.

Either way, it is very unlikely that you will come into contact with the mains voltage. However, do make sure the light is turned off at the switch. The main reason for turning it off is to ensure you don't short out the transformer when poking around with pliers, as that could possibly destroy it - but even then it would still keep the 220V away from you.

hdhondt
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  • I don't like that as a blanket answer - "you cannot get a shock from 12 volts" - try touching a car battery. – Tetsujin Oct 20 '14 at 07:23
  • @Tetsujin I have touched car batteries and have never felt anything. Even if you do feel something, the current from 12V will never be dangerous - and I assume that is what's meant by "a shock". I regularly test 9V batteries by licking them. Yes, I do feel that, but that does not imply there is any danger. – hdhondt Oct 21 '14 at 09:43
  • it's not the voltage that kills, it's the ampage. Sufficient ampage at 12v will kill you just as dead. Compare that to the spark from a rubbed ballon - thousands of volts, almost zero amps. – Tetsujin Oct 21 '14 at 09:48
  • Thank you, I have chosen your answer but I am unable to vote it up as my rep is below 15 :( – Mag1cboy Oct 21 '14 at 14:51
  • @Tetsujin, how do I find out who many amps is at the socket? – Mag1cboy Oct 21 '14 at 14:55
  • @Mag1cboy It does not matter how many amps the socket can provide. What matters is the current through the body. That is determined by the body's resistance, via I=V/R. When you just touch a 12V terminal the current will always be low and not dangerous. Even Tetsujin will find it difficult to imagine a situation where it could possibly be dangerous. – hdhondt Oct 22 '14 at 10:31
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You wouldn't get a lethal shock if you touched live 12 volts (you might feel a tingle), but it would be easy to damage the socket. Shorting out the contacts with the pliers could put more current through it than it is designed to handle. As long as the light switch is off, you should be OK.

fixer1234
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There is a slight danger, in the general case, that a bunch of 12V lamps have been wired in series so they can plug into an outlet (similar to the old-fashioned Christmas tree lights). Normally, in this case, if one lamp goes out they all go out, but there are ways to prevent that, so you can't really know for sure that it's not the case.

There is also a slight danger that, instead of a regular transformer an "autotransformer" has been used. This device works like a regular transformer but does not isolate the "load" side from "the mains".

Neither of these arrangements would be legal in the US or in most of Europe, but you never can tell what some DIYer may have done, if the lamps were installed by the previous occupant.

There's also the danger that the transformer is simply defective.

Given all this, it's prudent to disconnect from "the mains" before working on the circuit. Or, at the very least, use insulated pliers.

Daniel R Hicks
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