I want to upgrade my old fashioned fuses with fuse wire to modern circuit breakers.
I am not sure if I need a 10A or 20A circuit breaker for my hotwater cylinder. On the socket it is marked 10A, but the fuse plug itself is marked 20A. Which one is it supposed to be?
Cylinder is a Rheem 180L low pressure unit with 3000 watt element. It is about 2 years and replaced a 135L unit that was a good 50 years old.
jc239,
Dec 27, 6:02am
3kw is bout 12amps, 16amp mcb would be better, hard to say exactly though, depends on cable size
ryanm2,
Dec 27, 6:06am
The ol' old fuse board with the new 3kw element trick. Firstly before chucking 10 and 20 amp fuses all over the place you really should check the size of the cable the fuse is protecting. You may require 6A or 16A plus a 25A or 32A for your range. Just sticking to your first topic for now a 3kw element will draw around 12.5 Amps give or take. However, being an old board you probably have a round switch on your board turning the hot water on and off. This switch is only rated for 10A and will fail, sooner or later, so get that replaced , whilst the sparky is at your house he / she can check cable sizes so appropriate sized fuses are used. The porcelain fuse bases have to be changed as well, however if you change all of them you have changed all your circuit protection and therefore current regs come into place which then requires RCD protection too. Then you may as well just get your board replaced.
If you are really keen to do it yourself I would suggest buying 6A for the lighting circuits and 16A for everything else excluding range.
aredwood,
Dec 27, 4:31pm
Hope the cable to the cylinder has been upgraded at some point. As some of the really old 135L cylinders had a 1kW element that was supplied with a 1mm2 cable. (same size as lighting circuits) A 1mm2 cable will be Waaaaaay overloaded with a 3kW element on it.
easygoer,
Dec 27, 6:54pm
Water heaters were always wired with 3/029 cable then 1.5mm when metric cable was introduced, later when larger elements became the norm 2.5mm cable was used, a water heater wired in 1.0mm will most likely have been wired by a DIY enthusiast with no idea as to current draw or good practice
toymit,
Dec 28, 5:58am
What if the lighting circuit has one of those Heat/Light/Fan contraptions in the bathroom. Would that change what circuit breaker you use?
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