Plugging a lower drain machine into a higher drain outlet is perfectly fine, the outlet will be able to deliver all that the machine needs. And the machine will only use up what it needs, so having excess at the outlet isn't going to hurt anything. The other way around, a machine pulling more than the outlet can deliver, will trip the breaker or blow the fuse.
The four blade dryer plug brings a separate ground wire from the machine to the electrical grounding system. The three blade dryer plug depended on the neutral wire of the plug to make this connection.
It may work but will probably surge it...power coming in from both directions
This is a special purpose outlet, likely for a dryer. Normally in a house electric panel you have 120 VAC as the normal and 220 or 240 as a higher voltage. The 30 A is for 30 Amps. You can only plug in an appliance that has those ratings. You can't plug in a 120 V device.
You can use the wire rated for 20 amps on a 15 amp receptacle but you can not use a 20 amp fuse on any device rated at 15 amps. This is a tricky part of the code about receptacle outlets, You can use a 15 amp duplex outlet on a 20 amp circuit. (duplex outlet two devices can plug in) If it is a single outlet then the outlet must be rated 20 amp. NEC table210.21(B)(3). ============ A 15 amp duplex receptacle can be wired to a 20 amp rated circuit. This means the breaker OR fuse protecting the circuit can be rated 20 amps if the wire is also rated at 20 amps (12 AWG). --Sparkfighter
You would have a code violation, only a 50 amp/250V plug would fit into a 50 amp/250V receptacle. You would not have proper overload protection, the load could (worst case) call for more amps than it is rated for and catch fire before the breaker tripped.
The four blade dryer plug brings a separate ground wire from the machine to the electrical grounding system. The three blade dryer plug depended on the neutral wire of the plug to make this connection.
Well it depends. An outlet will spark when you remove a plug if the machine is still on, so make sure you turn the thing off before you pull the plug out.
You will burn up your appliance!!!!!
An outlet with too many volts in it or a short.
It may work but will probably surge it...power coming in from both directions
It is likely broken if there is power to the outlet
That happens when the appliance supplied by the outlet is switched off.
The voltage in a UK outlet is about twice that of a US outlet, which means you could ruin your sewing machine trying to plug it in. In order to use your US sewing machine in the UK, you'll need to purchase a voltage converter (transformer), and then you'll need to buy a UK adapter (since the transformer plug doesn't match UK outlets).
This is a special purpose outlet, likely for a dryer. Normally in a house electric panel you have 120 VAC as the normal and 220 or 240 as a higher voltage. The 30 A is for 30 Amps. You can only plug in an appliance that has those ratings. You can't plug in a 120 V device.
plug it into any outlet
Powed cords always plug into an outlet.
You can use the wire rated for 20 amps on a 15 amp receptacle but you can not use a 20 amp fuse on any device rated at 15 amps. This is a tricky part of the code about receptacle outlets, You can use a 15 amp duplex outlet on a 20 amp circuit. (duplex outlet two devices can plug in) If it is a single outlet then the outlet must be rated 20 amp. NEC table210.21(B)(3). ============ A 15 amp duplex receptacle can be wired to a 20 amp rated circuit. This means the breaker OR fuse protecting the circuit can be rated 20 amps if the wire is also rated at 20 amps (12 AWG). --Sparkfighter