I know that the UK has a 240-0 electrical mains and the US has 120-0 and 120-0-120 for the use of high power devices. (0 means neutral). I know I sound dumb here, but could you use a UK 220v preheat choke (not autotransformer or SRS) on the American 240v? Could you use it on 120v either?

There is still another difference and that is frequency.

For the ballasting purpose you do care mainly about the impedance (apparent resistivity, or how to call that), that is the effect limiting the current.
With an inductor, the impedance is L*2*pi*f, so 60 instead of 50Hz means 20% higher impedance. That means on the same voltage 20% lower current. For most fluorescents that is not that much an issue, so it will work.

The problem is safety: The light fixtures, installation and their design count on the fact there is just one line with voltage against ground, while you will have both. So e.g. you will need a double pole wall switch (to control both phase lines) to be safe and so on.
Therefore the code just does not allows to use the 240V for lighting.
The exceptions are large industrial installations, but there the required safety things (two pole control, local fixture disconnects,...) are installed.

If you use an autotransformer inside of the fixture, it is OK, as it is part of the fixture, so it's safety should be considered the same way as with any electrical equipment design (covers,...; normal ballasts generate even 600V and yet it is OK) The feed installation is still just 120V.

So the US 120-0 (neutral)-120 setting would work on an UK preheat choke? Other places round the world have 240v 60hz and Japan has 100v 50/60 hz, depending where you're at and their 100v ballasts work fine and draw less current and run cooler on 120v...

Just so we're clear, it's this set up that would work:

So the US 120-0 (neutral)-120 setting would work on an UK preheat choke? Other places round the world have 240v 60hz and Japan has 100v 50/60 hz, depending where you're at and their 100v ballasts work fine and draw less current and run cooler on 120v...

It will work the 120+120, but with 20% lower current than originally designed.

The mains voltages in use are mainly the 120V/60Hz and 220..240V/50Hz, Japan has 100V/Hz (so the inductive ballast are the same as for 120V/60Hz).
I do not now about any place with standard (home) installation 240V/60Hz (do not count the "120+120" as in US, that is just for high power or an industrial use).

Only in China is quite a mess (from HK comes the UK legacy, the mainland has very frequently imported systems from the US investors,...), due to the chaos how the electrification is developing there (that's, why they preffer electronic ballasts - as those are quite immune when it comes to any parameter, once the voltage is at least similar)...

Yep it will work, few things though :

1. We dont have "14-20" chokes, it is "18w" for 18W T8, it can run the 18 T8, 20 T12, 18/24 PL-L, 26 PL-C/PL-T, 28 2D (a bit underpowered though), and 22 circline. Its not suitable for 14W lamps. We have another choke for 15W T8, maybe that will work

2. With 240V you can run pretty much everything all the way up to 100W 8ft on a choke (without capacitor), as well as 2 x 20W in series on one choke

You may need special starters above 65W. The 65W lamp is still about the same voltage as 40W so FS-4 starter will handle it even if not rated, but the starter life may be somewhat shorter due to the higher preheat current so more arcing between the starter contacts. Above that it may not allways be able to start the lamp. For 2 x 20 use FS-2

3. 277V may be a better choice if you have that avalable. The higher voltage will compensate somewhat for the frequency change

4. If there are parallel PFC capacitors, the capacitor will draw higher current by the same 20%, so "over correct" the power factor. you have to use a capacitor of value 60% of what is used on 50 Hz for 240V or 80% for 277V. But you can just run it low power factor without the capacitor

5. For series capacitor and SRS the 60 Hz still may be a problem. I am not sure if you can just tweak it by changing the capacitor

South Korea uses 220V 60cy/sec with a system like our split phase 120V/240V system except the center tap is only used as a ground point and both current carrying conductors in a properly functioning system are hot with respect to ground.  Saint Kitts uses 230V 60cy/sec, but they also use 50cy/sec at the same potential.

If the only reason you want to use a 230V choke ballast is for collection and demonstration purposes, then the safest way would be a voltage converter (the transformer kind, the black box that has a fuse, universal outlets, etc, not the cheap wall wart travel converters). They can be had for about 200 dollars on eBay. I believe those have a 230V to neutral configuration.

With that being said, could I also run a SRS unit or is that completely different.

Safety design of European appliances (and that include lighting) is different in some things from US safety design. One thing where difference takes place is the treatment of Neutral :

In the US, many appliances have polarised 2 pin plugs to provide correct placement of the Neutral. This is a safety measure : The switch on an appliance switches the Phase, the screw base of a lamp screwed partially out of the socket will be at Neutral potential, and so on

In Europe, appliance design is making no assumptions on which wire is which. Several European receptacle/plug designs have no way to require insertion of the plug in a certain way at all. So the appliances are isolated equally on Phase and Netral, screw base lamp sockets break contact from both sides when the lamp is partially out, and so on

So i dont see any concerns whatsoever with connecting 240V applince between 120/120, and switching off only one side of it in normal use. In Europe you would have 1/2 chance of it being at 240V when switched off, and there is no problem with that. If you are going to take it apart and mess with the insides then just unplug it....



The 120/240 transformers can be of any of 3 configurations :

1. Isolated : The output wires are at 240 between them but no defined voltage to Earth
2. Common at 120V Neutral : Output is 0/240
3. Common at 120V Phase : Output is 120/120

You can change between 2 and 3 by swapping Phase and Neutral in the 120V side

The connected appliance won't mind which configuration you use anyway



SRS is based on the resonance point of the ballast+lamp system shifting in a certain way respective to the line frequency as the lamp is starting

It might "work" on 60 Hz but over stress the capacitor (which will make it fail sooner), it might be able to work right with changing the capacitor value, and it might not be possible to make it right at all. Which of them is really the case i dont know

Hongkong mains used to be 200 volts at 50 cycles now being gradually changed to 220 volts. Taiwan has 240 v at 60 cycles I know this cos I got a dehmidifier from there it seems happy enough on  my 250 volt 50 cycle supply.
UK mains plugs are polarised and you cannot insert them the wrong way round unlike europlugs

I just looked at your diagram and one problem you might have is that the tube might have a slight glow all the time due to one live leg always being connected I don't think it will be much as its only the tiny capacity to earth that will cause a current flow. Of course you won't get that problem if you unplug it or have a double pole switch

I would have to use a DPST switch for it to be up to code. I need to get some 240v chokes from eBay or something and do some tests. I'd have to do this in the dubroom because this is the only easy to access 240v at 50A(?) for the hot tub.

Im not sure what NEC says about it, it could just as well forbid it anyway ("lighting in home is required to be 120V only" sort of stuff)

But you can connect the lights through a receptacle, just like highbays are, at least here (do they connect HID highbays through receptacle and plug over there too ?)

Then question remains whether it is ok to cut only 1 side of a 240V receptacle with the switch

I think it's unsafe to leave one line connect since it may become loose or I'f the fixture is damaged and the wire gets exposed.