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I have a two way switch (for an outlet), and it was for 16 AMP.

I went to a store and asked for a new one, and when I got home and was starting to assemble it, I noticed the new one was 10 AMP...

Is it ok to use a lower AMP model, or should I get a 16 (or more) AMP?

I am almost positive the charge on each outlet won't be more than 10 AMP, but I don't really know what happens if it goes over it (I'm almost sure the switch doesn't have a fuse).

By the way, the circuit is 15 AMP.

(As you may notice by the type of question, I'm a novice).

jackJoe
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  • This looks like this would be a better fit at diy.stackexchange.com It looks like you got your question answered though. – Kellenjb Oct 19 '11 at 13:05
  • @Kellenjb true, when I posted here I wasn't sure if it was the right place, but seems it was (at least for this Q). – jackJoe Oct 19 '11 at 14:05

2 Answers2

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If the circuit is 15A, you need at least a 15A switch, and preferably have some headroom; 16A is not that much. The 10A switch won't do. Problems to be expected: fast burning in of contacts (= wear-out) and possibly welding of the contacts (= dead switch).

stevenvh
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  • So if I go for a 20 AMP that would be ok, correct? Also, could you explain a bit why a lower AMP switch can cause fast burning of contacts? – jackJoe Oct 19 '11 at 08:33
  • 20A should be OK. Heavy duty switches use different contact material, like tungsten, which has a very high melting point. Low current switches use materials which work fine for low currents, but may melt locally by high current sparks. – stevenvh Oct 19 '11 at 08:37
  • But even if the connected appliances are drawing lower than 10 AMP, can that happen too? (I'm going to swap it by a 20A, but I'm curious to know this). – jackJoe Oct 19 '11 at 08:40
  • There's no direct limit where this starts. It happens for 10A as well, but the effect will accumulate more slowly, giving your switch a longer life, but eventually it will fail at 10A too. The switch's datasheet should give you data on longevity. At 10A this may be as high as 10000 operations, while at 20A this may be reduced to 1000 operations, for instance. – stevenvh Oct 19 '11 at 08:44
  • Now you confused me, you mean the 10A in spite of not behing adequate for my circuit, can handle more operations? – jackJoe Oct 19 '11 at 08:48
  • No, if you operate it beyond its rating it may fail Real Fast, even within a few tens of operations. Note that in my example longevity decreases drastically even with only doubling current. – stevenvh Oct 19 '11 at 08:54
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A major rule when dealing with mains power is that every cable, socket, switch, etc. must generally be capable of passing through all the current passed by the smallest upstream breaker without starting a fire or creating a hazardous condition. Even if a wire or switch is only expected to pass half an amp, if it's fed by a 15 amp breaker it must be capable of passing 15 amps. If a wire that could pass 15 amps without creating a hazardous condition would be impractically large in a particular application (e.g. with Christmas-light sets) then there must be a fuse or breaker upstream of it.

There are a few exceptions to this rule that allow for protection devices to be downstream of the cable being protected (at least in the USA, many appliances and power strips generally have fuses or breakers inside them rather than in the power cord). Generally, though, a switch should be sized to handle all of the current that might be "available" to it, regardless of what the load is expected to demand.

supercat
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  • Nice one. The issue here was that the store sold me a smaller AMP switch, and as you explained, that would be hazardous. – jackJoe Apr 10 '13 at 07:44