Author Topic: Cheap, electronic US-to-EU mains converters  (Read 2997 times)

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Offline wraper

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Re: Cheap, electronic US-to-EU mains converters
« Reply #25 on: November 05, 2023, 11:06:05 pm »
I doubt very much that you would be prepared to take legal responsibility for that statement. Just because you are unaware of a case doesn't mean they don't exist.[/color][/font][/b]
I doubt you are prepared to use logic. Any earthed mains powered device that is legally sold in EU must tolerate full mains voltage between earth connection and either of prongs as plugs are not polarized. Implying there is safety hazard if you halve that voltage makes no sense. And again, Norway uses the same sockets/plugs and has IT earthing system where neutral is not connected to earth.
EDIT: And if something like that exists, it should have never passed safety tests to begin with as both wires must be treated as live.

« Last Edit: November 05, 2023, 11:26:08 pm by wraper »
 
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Offline wraper

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Re: Cheap, electronic US-to-EU mains converters
« Reply #26 on: November 05, 2023, 11:17:45 pm »
If you have the common US 240-120V center tap grounded neutral power available, an industrial transformer like this https://www.ebay.com/itm/385206481442 would suit your purposes because it can be wired for isolation of the secondary 240V so that you can ground one side and call it neutral.  Inrush protection may be needed depending on your circumstances and proper fuses and or circuit breakers should be used.
Or you use autotransformer and make direct use of existing earth and neutral connections without doing any shenanigans.
 

Offline tridac

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Re: Cheap, electronic US-to-EU mains converters
« Reply #27 on: November 09, 2023, 01:45:52 pm »
Sure, an auto would be smaller for the power, but an isolation transformer would perhaps be safer for someone not familiar with electrical systems...
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Offline wraper

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Re: Cheap, electronic US-to-EU mains converters
« Reply #28 on: November 09, 2023, 05:18:27 pm »
Sure, an auto would be smaller for the power, but an isolation transformer would perhaps be safer for someone not familiar with electrical systems...
Preventing GFCI from tripping is not safer. The suggestion from Gregg of connecting "neutral" output wire from isolation transformer to earth is the dumbest. Since output won't be floating, you can get electrocuted form touching "live" wire and anything that is earthed but GFCI in electrical box won't have any clue that something gone wrong.
« Last Edit: November 09, 2023, 05:21:11 pm by wraper »
 
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Offline BrokenYugo

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Re: Cheap, electronic US-to-EU mains converters
« Reply #29 on: November 09, 2023, 06:38:06 pm »
For cheap? Use the 240V already in the building. Sometimes you find a place with a 240V air conditioner socket (15-20A) already installed. Or if you're comfortable assembling such things buy a sub panel and plug it into the stove or dryer socket (240V 30 or 50A) and install a 15A two pole breaker to give a 240V 60Hz split phase supply to a socket of your choice. Note that in an apartment you sometimes get 2/3 of a 208Y 3 phase supply so you'll have 208V and not 240.

UK/EU devices are designed to work with a power supply that has the neutral bonded to the earth at the installation source. US 240V is split phase and there is no earth-neutral bond in this case. It might be ok, or it might cause problems, ie with the mains input filtering. Proceed with care and caution if you choose to do this.

What hazardous situation do you envision? The power is earth/neutral bonded, heavily, around me with a ground rod every house (I think modern code is 2 per building with #8 wire) and a wire running down every pole, all bonded together, the earth is just connected at the center tap of the pole transformer 240V winding feeding the building instead of one end. In a mains filter the Y caps to earth would see less stress only having 120V across each rather than 240V across one.

The big gotcha that does come to mind now is RCD/GFCI protection on 240V circuits in the US is uncommon, the breakers are available albeit expensive and probably special order for 15A. Also don't trust a non contact voltage probe around split phase, mine (old and cheap) only triggers on split phase cables sporadically, I guess because it's sort of balanced power with no neutral load, so it radiates less?
 

Offline AVGresponding

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Re: Cheap, electronic US-to-EU mains converters
« Reply #30 on: November 10, 2023, 03:00:46 pm »
For cheap? Use the 240V already in the building. Sometimes you find a place with a 240V air conditioner socket (15-20A) already installed. Or if you're comfortable assembling such things buy a sub panel and plug it into the stove or dryer socket (240V 30 or 50A) and install a 15A two pole breaker to give a 240V 60Hz split phase supply to a socket of your choice. Note that in an apartment you sometimes get 2/3 of a 208Y 3 phase supply so you'll have 208V and not 240.

UK/EU devices are designed to work with a power supply that has the neutral bonded to the earth at the installation source. US 240V is split phase and there is no earth-neutral bond in this case. It might be ok, or it might cause problems, ie with the mains input filtering. Proceed with care and caution if you choose to do this.

What hazardous situation do you envision? The power is earth/neutral bonded, heavily, around me with a ground rod every house (I think modern code is 2 per building with #8 wire) and a wire running down every pole, all bonded together, the earth is just connected at the center tap of the pole transformer 240V winding feeding the building instead of one end. In a mains filter the Y caps to earth would see less stress only having 120V across each rather than 240V across one.

The big gotcha that does come to mind now is RCD/GFCI protection on 240V circuits in the US is uncommon, the breakers are available albeit expensive and probably special order for 15A. Also don't trust a non contact voltage probe around split phase, mine (old and cheap) only triggers on split phase cables sporadically, I guess because it's sort of balanced power with no neutral load, so it radiates less?

At no point did I specify "hazardous" as a potential situational outcome, though I suppose that's possible too. I said it "might cause problems" and that's what I meant. Some devices you might wish to connect will have mains status detection and might well see the neutral being 120V away from earth as a supply problem and not function as you intend them to.
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