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by sbradford26 1020 days ago
Largely yes a 1.5 kW device (a 12.5 amp space heater for example) is less safe on a 40 amp circuit. Since if it fail pulling more load than designed but not truly shorted the breaker may not trip. But if you put that space heater on a 15 amp circuit it would most likely trip the breaker. As other commenters have said the UK addresses that risk with fuses in the plug.

Also I recently redid my kitchen and I added an additional 20 amp circuit just for the kitchen island outlets and it has been super nice.
1 comments
bialpio 1020 days ago
Are safety concerns alleviated here by GFCI breakers? In what cases could this appliance pull more amps than it was designed for? I know it's not required for circuits outside kitchen and bathroom, but I was thinking about just replacing all the breakers with combined GFCI/AFCI ones (especially given that my circuits are so old that there's no ground on them, in which case code I believe mandates that the outlets are GFCI-protected and labeled as "no ground").
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sbradford26 1020 days ago
So the risk would be reduced. Since if the failure causes a electricity to travel anywhere other than the neutral it will cause the gfci to trip. A scenario where a device would pull more power would be a short developing in a heating element reducing its resistance. So it would just pull more power but all of the power is still going to the neutral and wouldn't trip the GFCI.

Also with replacing all your breakers it can increase safety. But first the breakers are not cheap. Second it can lead to a lot of nuisance trips, albeit that is better than it used to be with modern breakers.

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bialpio 1020 days ago
Gotcha, so I guess it'll only protect from electrical hazard but fire hazard is still going to be there...

Breakers are probably going to be a bit cheaper and easier than opening all the walls to redo the circuits though...

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sbradford26 1020 days ago
Yeah your AFCI in theory is supposed to help reduce fire risk. Since failures like that cause arcing. But yeah it will be around $60-$80 per breaker, but there is definitely cheaper than ripping open walls to re-run wires.
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bombcar 1020 days ago
GFCI is not a magic “make everything perfectly safe” - you could electrocute yourself to very dead without tripping a GFCI if all the power went down the main wires and none went to ground.
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