What 220v stuff would work on 110v?

[Robin]

I know most things 220v won't work on (USA) 110v but I have a mental block over resistive load items, like heaters or light bulbs etc.

Would a 220v electric radiator heater work on 110v but at double the amps?

Same question re electric blanket?

Same question re light bulbs?

If they DID work, would the amp rating for the cables be OK or too low?

I know I should know the answers but I've spent too long with DC electrics and my mind on AC is scrambled!

 

[savageseadog]

As far as head and (incandescent) lights go it's worse than you think. A 1KW 220/240V heater would operate at approximately a quarter of the power ie 250W. The current will not go up it will halve. The only electronic appliances that might work at both voltages and frequencies will be those deigned for dual voltage switchable or appliances with electronic power supplies. These items will be marked up as 100-240V 50/60Hz or similar, don't use anything not correctly marked.

 

[William_H]

Yes a heater or electric blanket might work OK on 110 volts but basically running on low power when set on high. Blower heater no good. As savageseadog says at 1/4 power. If you replace the globe in a light no probs provided it is not a low voltage type with transformer.

Many electronic transformers for battery charging and many electronic devices are designed to run on 240 or 110 volts. It will be clearly stated if this is the case. some computers etc have a switch to select 110v or 240v.
So not much really. olewill

 

[Amari]

On a slightly different tack, my boat although built in France was fitted out in USA. I tell myself, knowing nothing about electrics, that US 110 volts needs thicker wires so I assume shore power (Turkey 240v)travels round the vessel with a high safety margin, or is that bo**ocks?

 

[smonard]

I squared R! Double the current 4 times the heat!

 

[johnalison]

The only thing I know which would work on different voltages was an old Braun razor which would recharge on anything from 12 to 240 volts without adjustment.

 

[VicS]

For the same power a 110 volt appliance requires slightly more than twice the current of a 240 volt appliance.

Watts = volts x amps, or rearranged amps = watts/volts.
A 110volt, 1000watt appliance for example will therefore take 1000/110 = 9.09 amps.
A 240 volt, 1000watt appliancer will take 1000/240 = 4.17 amps.

However that is comparing two different 1000watt appliances (heaters for example), one intended to be used on 110volts and the other intended to be used on 240 volts.

Take the 240 volt one, Its resistance can be calculated from volts = amps x ohms, which rearranged is ohms = volts/amps, and is therefore 240/4.17 = 57.6 ohms
If this 57.6 ohm item is connected to a supply of only 110 volts the current that flows will only be 110/57.6 = 1.91 amps. so since watts = volts x amps the power it will produce will only be 110 x 1.91= 210 watts. Less than a quarter of the power if run on its correct 240 volt supply.

That's a long winded way of doing the calculation but I have deliberately done it like that to only use the two equations that most people recognise namely volts= amps x ohms and watts = volts x amps. I wanted to avoid expressions with amps² or volts² in them.

That goes part way to explaining why most 240volt equipment will not work satisfactorily on 110volts.

Regarding the cable sizes, because 110 volt equipment uses more than double the current that the same power equipment uses on 240 volt (just over 9 amps compared with a a little over 4 amps for 1000 watts) the cable must be heavier. So yes you have a big safety margin on cable sizes running an installation designed for a 110 volt supply on 240volts.

 

[MM5AHO]

This expains a lot.
Americans are about a quarter as powerful as Europeans, but are much heavier, and produce far less good??

 

[Robin]

Thanks all and especially VicS who gave the QED moment! I ought to have been able to get there and should probably hand back my A level Physics certificate, but over 40 years of thing only in 12v DC has given me tunnel vision!

 

[Anonymous]

There is quite a lot of dual-voltage kit about. My Dell supply is dual voltage, as is one of my razors, etc. But on the whole, no.

 

[Robin]

Yes we have quite a lot that is dual voltage too, from laptop & printer, LCD TV, hairdryers and even onboard smart charger, but I had this daft notion that a simple device that is basically a resistance wire glowing for heat or light would work equally well on half the volts but take twice the amps! I didn't sit down with pen and paper and do the basic sums but jumped to conclusions but as VicS demonstrated it might 'work' after a fashion but very inefficiently. The question arose because we plan to desert the sinking ship in a couple of years for destinations dollar and will be dumping lots of 220v stuff that we know won't work and going 110v.

 

[Anonymous]

It's usually easier to use a water analogy to get a handle on simple electrics. Pressure = Volts. Flow speed (metres per second along the pipe) = Current, Amps. Resistance to flow = Resistance, Ohms. Flow rate litres per second = Power, Watts. Total water passed in a given time, in litres = Energy supplied in kWh or Ah.

When it comes to Ohm's Law people tend to have a problem with 'cause and effect'. What causes things to happen is the pressure, in Volts. What happens when you apply a voltage to a simple resistive circuit depends on the resistance.

I think you're probably right to dump most of the 220V stuff rather than try to adapt it. Even mixing UK and EU plugs on a system is a darned nuisance; trailing transformers around would be even worse.

You could try selling the US area the idea that 220V is better (which it is). 110V was chosen for safety and these days that isn't an issue, with modern materials and techniques. By doubling the voltage, you get four times the power from wiring of the same size. Not bad, eh? Much more efficient.

 

[Graham_Wright]

You could of course use a 110/220 transformer back to front.

 

[stevebrassett]

How about something like this?

http://www.airlinktransformers.com/transformer/su7501-portable-tool-transformer.asp

Larger ones are also available.

 

[Robin]

Thanks but we will only be taking very limited electrical stuff anyway and I just wondered about a nice brass marine table light we have and thought it might work. As it happens we bought it in France and I think it has the same screw thread bulb fitting as USA bulbs so a simple bulb change might work on that, or I could change the fitting. All the other things apart from dual voltage stuff anyway like laptops, printer, LCD TV (multi system as well as dual voltage) are old enough not to be worth shipment or we won't have space for - we are going liveaboard on a boat.