I live in Pakistan and we have no electric panel or separate wires for different devices. I am going to rewire my house but before that I wanted to secure the refrigerator wire. I've been reading everywhere that there should be a 20A circuit breaker for the dedicated refrigerator line so I went to an electrical shop and asked him to give me a 20A breaker for it. He said that 20A is too high and I should get a 4A circuit breaker for it. We have a 220-240 single phase coming to our house. My refrigerator's nominal current is 1.25A (200W). The circuit wire is 7/0.29mm. I tried to object saying the breaker would keep tripping because its a big one but he said that he has been using the same breaker for his own big size refrigerator so it will work. Eventually I ended up buying it and attaching the refrigerator phase wire with it. Its been 3 days but still it hasn't tripped. So I want to know is it safe with this amp breaker? Why do we need a 20Amp breaker for it when 4Amp is working just fine?
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your breaker is 4A, your fridge is 1.25A. Why do you expect it to trip? Also: hire someone, your are obviously not qualified– ChristianCommented Jun 1, 2016 at 6:44
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Yes, I am definitely not qualified. I just want to know that why everywhere on the internet its mentioned that there should be a 20A breaker for the refrigerator circuit when the 4A circuit breaker works just fine.– SaadCommented Jun 1, 2016 at 7:36
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The firdge almost certainly uses an induction motor and these can pull 5+ times their normal current for a few thousandths of a second as they spool up, this doesn't hurt the motor and won't hurt the wiring (it's prolonged overcurrents that cause problems here), 20A seems a little overkill, maybe for a 500-1000W fridge, but for a 200W fridge, I'd be surprised if it pulled more than 4 or 5 amps for a few milliseconds (which is unlikely to trip the breaker anyway, they are usually not quite that sensitive). Most houses do not have dedicated breakers for every appliance though.– TomCommented Jun 1, 2016 at 10:08
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20A on a 120v system is the equivalent of 10A on a 240v system, and even that is a bit of overkill, possibly future proofing. Fridges were often on non-dedicated 15A/120v breakers in the past, leaving less than 7A on an equivalent 240v circuit for the fridge without issue.– BMitchCommented Jun 1, 2016 at 11:06
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@BMitch that explains it!– SaadCommented Jun 1, 2016 at 17:22
3 Answers
Commonwealth countries normally use British standards in electrical wiring. For household wiring, there will be two distinct outlet from the distribution/circuit breaker board. One is 6A lines for the lighting circuits, and another one is 20A lines for all power outlet sockets. Lighting circuits are wired using 1.25 millimeter squared wires and the power outlet wires are 2.5 millimeter squared copper cross section area.
So, what you might have read from the internet is, anything connected or plugged in to the outlet socket is protected by the 20amp breakers. These breakers are rated actually to protect the wires in the house wiring, not to protect the appliances plugged to the sockets.
Properly rated fuse is already attached in your appliance power plug or embedded in its internal wiring. The 200Watts chiller is definitely consumes less than one ampere nominal current and its startup current may be three times higher, no way a 20Amps breaker will protect it unless it fully burnt and melt down.
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Note that exact sizes does vary a lot between countries - 10A is standard for lighting here in NZ, and in 1mm^2 not 1.25 (I don't think you can get 1.25). Power varies between 16 and 20A. Commented Jun 1, 2016 at 10:56
Most advice you'll find online is for the US, which doesn't really apply to you. They use 120V, so appliances use more current for the same power, requiring more dedicated circuits. I wouldn't run a dedicated circuit for anything except the range (stove, oven, hob, whatever you call it) and hot water (if electric). Everything else is on one of a couple of general power circuits (or lighting).
"7/0.29" seems to be rated similarly to 2.5mm^2 copper, so would probably be on a 16A or 20A breaker.
The circuit breaker is (mainly) to protect against starting fires from circuit overloads. If the circuit is all 7/0.29, it can handle that current, and I would have no worries about a 16A circuit breaker.
4A is fine, but you then have a much thicker cable than needed ($$$), and will have nuisance trips if you ever try to plug something else in or add more sockets to that circuit.
The refrigerator's motor may surge current on startup, but the local electrical code will discuss whether this is an issue. Anyway, this is beside the point.
The point is, breakers protect wires. Whatever is the thinnest wire in that circuit - look up what amperage is permitted on that wire - the breaker should be no larger than that.
