Sorry for the basic question, I am not especially electrically minded.

I have a system that requires 16A and 240V power, however we only have 10A wall outlet power available.

I did consider connecting two transformers in series across two 240V 10A wall outlets to produce 240V 20A, however I'm not confident that this is the best/cheapest/most convenient solution.

Aside from having an electrician come out to install a 20A wall outlet, are there any convenient or more versatile solutions to this issue?

  • I doubt there's any standards-compliant way to do this short of installing a 20A outlet.
    – Hearth
    Mar 10, 2020 at 23:08
  • 2
    What country are you in - electrical systems vary between countries. In any case, this question would be better in the DIY stack (they'll still want to know where you are.) Mar 10, 2020 at 23:10
  • Any other method of supplying 20A 240V to a system? I've heard of Uninterruptible Power Supplies but am unsure if that would help here ?
    – solar_enemy
    Mar 10, 2020 at 23:10
  • I am in Australia
    – solar_enemy
    Mar 10, 2020 at 23:12
  • You need an electrician, which is a topic for DIY, not EE.
    – Dave Tweed
    Mar 10, 2020 at 23:30

3 Answers 3


Dude: Don't monkey wire this up. There's no way you;re going to get 16 amps at 240 out of a 10 amps outlet. I understand in the down under your convenience outlets are at 230 or 240, if not, and you are at 120, it's even much worse. But still, whatever you are supplying, do it right. The approach of parrallelling two transformers to deliver the needed amperage.... that would require them to be on the same phase forever. That is a hack job. Just run the correct cable and breakers and sleep easily.

  • I would agree and add not only on the same phase but the windings of the transformers would have to be the same you would be surprised the difference in a dozen transformers same MFG and specs, a phase shift over 30 degrees (this was a college electronics lab). You need an electrician to add a breaker to your customers unit for this load.+
    – Ed Beal
    Mar 11, 2020 at 2:14

Get to know your electrical equipment

I gather you picked a 10A circuit because it's the first one you looked at. But do an exhaustive search of your panel and your house's wiring. I bet you'll find circuits rated at 15A or 20A.

You might be presuming all power points are the same. Actually, they're not. Take a look: there are five different types, keyed differently to keep a too-large load out of a too-small power point. Do not defeat this keying. They appear to be downward compatible, and they look almost identical... so it wouldn't surprise me if there's a 20A power point in your house, right under your nose and you don't know it. Right under your cell phone charger.

But for sure, at bigger appliances like water heaters, space heaters, air conditioners, hob, washer/dryer, etc.

  • 15A outles are are rare in australin homes. 20A very rare. most dryers and heaters use 10A, many air conditoners need 15A, but plug-in air con is fairly rare.
    – Jasen
    Mar 11, 2020 at 10:31
  • I know the difference between 10A and 20A wall sockets, and I know that 20A sockets are downwards compatible. And Jasen is correct, 20A sockets are not common at all In Aus, so I’m sure I’m not simply confusing them. Thanks though... Mar 13, 2020 at 12:48
  • You will not find anything but 10A sockets in the average NZ home, plus a 32A socket for the hob/range and 15A for the oven if they are not hardwired - and the 32A could be any of about 5 different proprietary or standard options. Most commercial facilities will use ASNZS3123 instead. AU is I think similar except the appliances are more likely to be hardwired. Mar 30, 2020 at 14:49

I have a system that requires 16A and 240 power volt, however we only have 10A wall outlet power amperage available.

If you need 240v @ 16 amp then that is 3840 watts of power;

power is in units of watts and mathematically (generally speaking) is W = V x A.

If your circuit breaker only allows for 10 amps @ 240v then that's only 2400 watts of power available. You're short 1440 watts so depending on what you are looking to do you are probably going to need a new outlet installed and wired to provide 240v rated for 20 amps.

I did consider connecting two transformers in series across two 240V 10A wall outlets to produce 240V 20A

I cannot readily picture that wiring, but a transformer is used to convert AC voltage to some new voltage such as 120v to 240v, or 240v to 120v, or 120v to 5v (usb phone charger) etc. And in doing so, the given transformer is only rated to deliver so much power. For example if you had 240V @ 10A that is 2400 watts of power and to keep the same amount of power at 120V there would need to be 20A. Any transformer will have a power output rating, you are looking for 3840 watts of power and I don't thing you are going to find anything for consumer/residential use at that power level. Not to mention you already have 240v available, so you don't need a transformer. Your problem is not enough amperage available which using a transformer will not solve.

Aside from having an electrician come out to install a 20A wall outlet, are there any convenient or more versatile solutions to this issue?

Doing this would provide the simplest means (and probably safest) of getting the necessary amount of amperage at one outlet for use. With nothing other than electrical wiring in mind (somewhat considering your in Australia and however they do electrical down there) it sounds like you have all 10 amp outlets to work with at your location so you would simply need is wiring from 2 separate 10 amp outlets that are on the same phase from your load center panel then run in parallel to your load to provide 20 amps; this would be the most convenient (inexpensive) way of making use of what you have available but since you said I am not especially electrically minded this is something you should not do yourself and would be better to refer this info to someone else technically competent and knowledgeable about doing something like this.

I've heard of Uninterruptible Power Supplies but am unsure if that would help here

it might depending on how long you need 3840 watts of power for. What will happen is you only have 2400 watts of 240v power providing 10 amps to charge the UPS. If you pull 3840 watts from it you will be discharging that UPS and that will only last for however long. Repeated heavy draining of a UPS like this will not help it last long, a UPS rated to deliver that much power may not be available for residential/consumer and certainly would not be cheap- it would probably be best to get a 20A outlet installed instead.

consider buying a cheap generator powered by a single cylinder gasoline engine. They are typically rated at 5000 watts output capable of ~7000 watts surge, and they provide a 240 volt outlet which i think is rated at 20 amp.

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