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I wish the same about people who sell adapters for plugging 15A electrical devices into 25A electrical outlets. Sadly, the legal burden is placed exclusively o

I wish the same about people who sell adapters for plugging 15A electrical devices into 25A electrical outlets. Sadly, the legal burden is placed exclusively on the buyer (via electrical code).

jessaustin 6y ago
I don't see how such a product would be useful for anyone. At least in USA, anywhere a 25A circuit is available, a 15A circuit is also available. The converse (using a 25A device on a 15A circuit) would be useful, but also wouldn't be dangerous in any way.
- toast0 6y ago
  Looking at us (NEMA) plugs, there's plugs for 15A, 20A, 30A, and 50A. I'm going to assume everyone means 30A instead of 25A. Generally, where there's a 30A circuit, a 15A circuit is also available, but there are exceptions. You may have wired a RV hookup with only a 30A receptacle, but you want to run some lights, or tools or ? with a 15A plug from that on a temporary basis. The circuit is (presumably) good for 30A, so adapting to a lower amp receptacle is reasonable --- it won't hurt anything to draw fewer amps through the circuit. Adapting from a 15A socket to a 30A socket can be dangerous; the 15A or 20A[1] breaker or fuse on the circuit won't immediately open with a 30A draw, and the wiring will heat up during the time it takes for the circuit protection to open; possibly long enough to cause a fire. Of course, just because a load has a 30A plug doesn't mean it draws 30A all the time, there are conditions where using such an adapter is safe, but it requires knowledge of the load. [1] US NEC code allows for a 20A breaker on circuits served by 15A receptacle, as long as there is more than one receptacle
  - mikepurvis 6y ago
    If the 15A device fails short, it's going to get a much bigger load between failure and the breaker tripping on a 30A breaker than a 15A one.
blinky1456 6y ago
Why does it matter if you plug 15amp device into a 25amp oulet? Surely It will only use 15amps unless it short circuits?
- floatingatoll 6y ago
  It matters if it short circuits, yes. (Electricians, I hope I got this right enough to convey the 'why'; I know it won't be perfect.) The outlet plugs specify the circuit breaker limit. Most consumer electronics in the US use a 15amp plug, which can be plugged into a 15amp outlet or a 20amp outlet — but no higher, due to physical incompatibilities in the outlet design. The electronics that use the 15amp or 20amp plugs are therefore built not only to draw no more than the amps rated by their plugs, but also to self-destruct relatively safely if they draw the maximum amps available from the circuit breaker backing that plug. So if a cheap device correctly assumes as part of its "don't explode" protections that it will never receive more than 20amps due to using a 15-or-20 amp plug, and then it short circuits while plugged into a 25 amp circuit using an adapter, it could very well explode, because the basic guarantees of electrical safety were violated. The plug used guaranteed it would never receive more than 20amp, and now it's receiving 25! This is especially relevant when you're considering how to make use of an idle 30A dryer outlet in a garage. If you just plug an adapter into it, and your device short circuits, it will explode even more violently. Risk of harm increases with outlet power. There exist fancy "breaker box" adapters that have a 30A plug on one side, a fuse box with a 15A or 20A fuse in the middle, and a 15A outlet on the other side for you to use. It's not really an adapter at that point, but the presence of that 15A/20A fuse provides the missing piece of protection for your 15A/20A device that a plain adapter wouldn't have. So in summary, the only way to safely use a 15amp device on an outlet that delivers power higher than 15-20A is to somehow inline a 15-20A breaker between the device and the outlet (or, to rewire the outlet and its power feed to 15-20A). TL;DR: Hire a licensed electrician to tell you what your options are and decide how much you care to spend and whether you want to make permanent modifications to get the job done.
  - Dylan16807 6y ago
    Any device that becomes significantly more dangerous when the breaker trips at 25 instead of 20 amps is relying on way too thin of a safety margin and I would consider it a lurking hazard on any circuit.
numpad0 6y ago
You can’t “oversupply” electrical current(Amps), only voltages(Volts). Current is drawn and determined by Ohm’s law.
- mikepurvis 6y ago
  It matters in the case of a malfunctioning device, as others have pointed out. If you're going to have an adapter than a allows a 15A device (which would normally only need to fail safely in the presence of 15A, or perhaps a very brief lighting surge) into a plug that can supply 25 or 30A, the adapter should almost certainly contain its own 15A fuse. The reverse of this is plugging big loads like power tools or vacuum cleaners into extension cords intended for use with desk lamps, but I think most people understand that that's a bad idea.

I wish the same about people who sell adapters for plugging 15A electrical devices into 25A electrical outlets. Sadly, the legal burden is placed exclusively on the buyer (via electrical code).

jessaustin 6y ago

I don't see how such a product would be useful for anyone. At least in USA, anywhere a 25A circuit is available, a 15A circuit is also available. The converse (using a 25A device on a 15A circuit) would be useful, but also wouldn't be dangerous in any way.

toast0 6y ago
Looking at us (NEMA) plugs, there's plugs for 15A, 20A, 30A, and 50A. I'm going to assume everyone means 30A instead of 25A. Generally, where there's a 30A circuit, a 15A circuit is also available, but there are exceptions. You may have wired a RV hookup with only a 30A receptacle, but you want to run some lights, or tools or ? with a 15A plug from that on a temporary basis. The circuit is (presumably) good for 30A, so adapting to a lower amp receptacle is reasonable --- it won't hurt anything to draw fewer amps through the circuit. Adapting from a 15A socket to a 30A socket can be dangerous; the 15A or 20A[1] breaker or fuse on the circuit won't immediately open with a 30A draw, and the wiring will heat up during the time it takes for the circuit protection to open; possibly long enough to cause a fire. Of course, just because a load has a 30A plug doesn't mean it draws 30A all the time, there are conditions where using such an adapter is safe, but it requires knowledge of the load. [1] US NEC code allows for a 20A breaker on circuits served by 15A receptacle, as long as there is more than one receptacle
- mikepurvis 6y ago
  If the 15A device fails short, it's going to get a much bigger load between failure and the breaker tripping on a 30A breaker than a 15A one.

blinky1456 6y ago

Why does it matter if you plug 15amp device into a 25amp oulet? Surely It will only use 15amps unless it short circuits?

floatingatoll 6y ago
It matters if it short circuits, yes. (Electricians, I hope I got this right enough to convey the 'why'; I know it won't be perfect.) The outlet plugs specify the circuit breaker limit. Most consumer electronics in the US use a 15amp plug, which can be plugged into a 15amp outlet or a 20amp outlet — but no higher, due to physical incompatibilities in the outlet design. The electronics that use the 15amp or 20amp plugs are therefore built not only to draw no more than the amps rated by their plugs, but also to self-destruct relatively safely if they draw the maximum amps available from the circuit breaker backing that plug. So if a cheap device correctly assumes as part of its "don't explode" protections that it will never receive more than 20amps due to using a 15-or-20 amp plug, and then it short circuits while plugged into a 25 amp circuit using an adapter, it could very well explode, because the basic guarantees of electrical safety were violated. The plug used guaranteed it would never receive more than 20amp, and now it's receiving 25! This is especially relevant when you're considering how to make use of an idle 30A dryer outlet in a garage. If you just plug an adapter into it, and your device short circuits, it will explode even more violently. Risk of harm increases with outlet power. There exist fancy "breaker box" adapters that have a 30A plug on one side, a fuse box with a 15A or 20A fuse in the middle, and a 15A outlet on the other side for you to use. It's not really an adapter at that point, but the presence of that 15A/20A fuse provides the missing piece of protection for your 15A/20A device that a plain adapter wouldn't have. So in summary, the only way to safely use a 15amp device on an outlet that delivers power higher than 15-20A is to somehow inline a 15-20A breaker between the device and the outlet (or, to rewire the outlet and its power feed to 15-20A). TL;DR: Hire a licensed electrician to tell you what your options are and decide how much you care to spend and whether you want to make permanent modifications to get the job done.
- Dylan16807 6y ago
  Any device that becomes significantly more dangerous when the breaker trips at 25 instead of 20 amps is relying on way too thin of a safety margin and I would consider it a lurking hazard on any circuit.

numpad0 6y ago

You can’t “oversupply” electrical current(Amps), only voltages(Volts). Current is drawn and determined by Ohm’s law.

mikepurvis 6y ago
It matters in the case of a malfunctioning device, as others have pointed out. If you're going to have an adapter than a allows a 15A device (which would normally only need to fail safely in the presence of 15A, or perhaps a very brief lighting surge) into a plug that can supply 25 or 30A, the adapter should almost certainly contain its own 15A fuse. The reverse of this is plugging big loads like power tools or vacuum cleaners into extension cords intended for use with desk lamps, but I think most people understand that that's a bad idea.