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Firstly, this is in France so we're talking 220V power.

I've got two new single/individual induction hobs. They're both 2100W at full blast. I'm replacing a double hob unit where one hob was 1900W and the second one was 1400W. For one 20A fuse, there are two sockets in my kitchen. One socket has, on a power strip:

  1. a microwave - 1400W microwave and 1300W toasting both of which I do often, and 3100W max for oven duties which I never use.
  2. a small convection oven (2900W), almost daily use

It's the second socket I want to put these hobs on. But I don't know what to calculate to see if everything will be fine and would love some help with the maths.

What I know for sure, usage-wise...

  • I've had microwave and oven at full blast and both the old 1900W hob and the 1400W hob in use and never had problems.
  • The only time I'll ever go up to full blast (2100W) on the new hobs is when I'm boiling water and even then it'll only be on one, never on both.
  • Everyday cooking will hardly ever go above halfway, power-wise, so we're talking 1100-1300W max. But using both at that strength is common for my cooking.

Am I leaving anything out for someone help me out? Am I just adding up amps and that's that? Or is it more complicated than that? I'm asking now because before the hobs were 1900W and 1400W and now they both have the potential to be stronger. So, I'm concerned. And also, I'd simply like to learn about consumption more.

Thanks!

5

Simply if both of those kitchen outlets are supplied from the same circuit with the 20A fuse you have a problem.

The maximum available power is: 220VAC * 20A = 4400W.

It is usually recommended that a circuit be derated to 80% of it's fused capacity for loads that may be on for any length of time. That takes your recommended available usage to 3520W. So any usage combination the you come up with from that mix of loads that goes over 3520W is a hazard and should be avoided.

So ... you should definitely be considering the the addition of a new circuit to your kitchen for the new dual burner unit. Call in a professional electrician and they can tell you what you need to be safe and code compliant in your area.

  • Thanks for the help! I have another circuit right below that one, on a 20A fuse that is only there for the fridge. I'd have to use a splitter of some kind but would that be better for putting one of the two hobs? Possibly both? By the way these are separate single hobs with regular plugs for wall outlets. – tinpanalley May 30 '16 at 15:09
  • I still suggest that you have an electrician come out and pull in an additional NEW circuit (if not two). You are are the fast dangerous lane with overloading the one you have and trying to pull off the refrigerator circuit does not sound like a good idea. Some locations even specify an independent circuit for a refrigerator. It sounds like you live in a place with 1950 style wiring and are trying to deploy appliances never anticipated by the original setup. It is time for a major upgrade. – Michael Karas May 30 '16 at 16:59
  • Thanks again. Really appreciate your help. The thing I don't get is that I have, several times, been in this situation... - strong on the hob at about 1700W boiling water - the oven at 200C for 40 minutes - the other hob at about 600W - the microwave for a short 1 minute burst on high, so another 1400W I've never had anything, any cables, go wrong or even get remotely hot. How did I get away with that for the past three years? And what can I do to replace that double 1900W-1400W hob with the two 2100W individual ones? – tinpanalley May 30 '16 at 18:02
  • I'll say it again. Get in a licensed electrician from your region that understands the local electrical safety code and can analyze your setup first hand. They will be able to provide the proper suggestions. As to how you got away with things.....maybe luck.....but don't push it. An electrical fire is not something you want to have happen. – Michael Karas May 30 '16 at 18:11
  • If you actually do have fuses you may want to carefully check to see if things there are Ok. People have been known to place a coin under a screw in fuse to "work around" a fuse that went open due to overloads that they wanted to stay powered. Snap in cartridge fuses also have a number of shortcuts that people have tried albeit very dangerous. – Michael Karas May 30 '16 at 18:18

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