Appliance Voltage and Travel Issues

IMPORTANT NOTE

The National Electrical Code in the U.S. allows for appliances to be supplied at 240 V only if they would draw more than 12 amps at 120 V (1440 W). So, small appliances are not allowed to be plugged into a 240 V outlet, even if they are rated (for use elsewhere) for that voltage. NEC 210.6 (A) (2).

Further answers

Some small portable 50 Hz appliances - such as electric shavers, battery chargers for cell-phones, cameras, music and video players, laptop or netbook personal computers, etc. - have been designed to run safely on different supply voltages and frequencies. Whenever that is so, it should be clearly stated on the appliances' rating-plates. In many such cases, where the power needed is low, say less than 30 Watts, a cheap and simple "International Travel Socket Adapter" is all that is needed to make the appliance plug-in and work. Many international airports have shops selling such adapters.

But, for most other household appliances, in general the answer has to be: "Not if the appliance was designed and wired to run only on the 50 Hz power service that is used in Europe and elsewhere."

The mains frequency in Europe and other 230 volt areas is 50 Hz (cycles per second) compared to 60 Hz in US, Canada and other 120/240 volt areas. Some 50 Hz appliances may work fine but others with simple motors will run too fast on the higher frequency of 60 Hz.

However the most important difference is how the Neutral wire is connected:

240 volt 50 Hz service

A 240 volt 50 Hz appliance can have up to 3 wires altogether:

• one single 240 volt "live" or "hot" wire;
• a neutral wire;
• a safety "earth" or "ground" wire but this is not required if the appliance is of the type known as "double insulated".

The hot wire feeds alternating voltage from the power station to the load and, because the voltage is alternating, the load draws an alternating current. Then the neutral wire returns the current to the power station to complete the circuit.

240 volts 60 Hz service

An appliance that is designed to be connected to strictly 240 volts 60 Hz is connected with only a two wire cable plus a safety ground wire. (For example 240 volt 60 Hz base board heaters use that.)

The only time a cable with three wires plus safety ground is used is if 120/240 volts is needed in the equipment. (For example kitchen ranges or washing machines which have time clocks or programmers that require only a 120 volt feed.)

Thus an appliance designed to run on a 240/120 volt 60 Hz supply can have up to 4 wires altogether:

• two 120 volt 60 Hz live "hot legs" which run in opposing phase to one another: when one hot leg goes "+" (120 volts positive) the other leg goes "-" (120 volts negative);
• a neutral wired as a "central" common current return conductor:
• a safety "ground" wire but this is not required if the appliance is of the type known as "double insulated".

One of the two hot wires feeds a 120 volt alternating voltage from the power station to the 120 volt load - the clock or programmer - and, because the voltage is alternating, that load draws an alternating current. Then the neutral wire returns the current to the power station to complete the circuit.

Important conclusion

There is a 240 volt voltage difference between the neutral and the hot conductor in the 50 Hz system and only a 120 volt voltage difference between the neutral and each of the hot conductors in the 60 Hz system.

That is why an appliance designed to be connected onto the 50 Hz system cannot be used safely on the 60 Hz system without first having a proper technical inspection done, followed by any necessary modification work done to ensure that the appliance can be operated safely because, in the main breaker box, at the point where the 60 Hz "neutral" gets connected to the ground, this difference will cause serious problems!

A licensed electrician or electrical engineer would be able to consider whether or not a particular large appliance, that was manufactured to work on 50 Hz-only, could be modified to run safely at the higher 60 Hz frequency. However it won't usually be worth the expense of doing the work because it would be more cost-effective to buy (new or secondhand) an equivalent large appliance designed to work on 60 Hz.

A further answer from briank101:

Several appliances such as European electric kettles can be connected to the US 240 volt supply. I have done this successfully and safely. It has been absolutely worth it. One just needs to purchase a long extension lead that has a receptacle that matches the plug on the kettle (Buy this in the same country where the kettle was bought). You will cut the 3 pin plug off the extension lead and leave the rest of the extension lead intact. You will wirestrip the cut end to wire it into the 240 volt supply. As long as the ground within the European appliance is not in any way connected to the neutral within the European appliance, it appears that this method is doable. It is extremely important that the European ground or earth conductor is connected to the US ground conductor. Very importantly, the European Neutral conductor is not connected to the US neutral conductor, it is however connected to one of the live US phases and the European Liveconductor is connect to the other live US phase within the US 240 Volt outlet (The US uses a split phase). The voltage between the 2 US live conductors is 240 Volts, which will now be the voltage supplied between the European Live and Neutralconductors. The American neutral conductor is not used in this configuration and must be isolated in this specific setup. Do not attempt this if there is any doubt in your electrical capabilities. I have connected a European 3300 watt electric jug kettle to my US 240 volt supply this way and it has been one of the most satisfying mini projects that I have performed. I can boil 2 cups of water in about a minute. It would take almost 3 minutes in 1250 watt American kettle. If your kitchen is located above or near a 240 volt outlet, it is a really straight forward job to run wiring to it.

A comment from Martinel:

Maybe this is getting to be like a discussion page but I think it's very important to say this: be very careful to ensure you know the risks you are taking because your existing 60 Hz 240 volt branch circuit would typically be protected by a breaker specified for a dryer, a water heater or a similar powerful heating device.

Because of the current drawn by the appliance on the circuit it's protecting, that breaker could be for 30 amps, 40 amps or more.

I know exactly how great the performance of a such a kettle is! If you are someone technical enough to really know what you are doing I'm not saying you should not do what you have described at all. But I am saying it would be best practice to say - as part of your instructions to the general public here - that it is necessary to install a separate 240 volt branch circuit protected by a 16 amp (or max 20 amp) breaker and having a socket outlet that is different in size and shape to the one you have on your existing 30 amp or higher branch circuit.

The European 3300 watt kettle takes a bit less than 14 amps so your standard US 240 volt circuit will not be properly "breaker protected" for the kettle. In mainland Europe such a kettle would be plugged into a branch circuit protected by a 16 amp breaker. In the UK and Eire (Republic of Ireland) such a kettle would be plugged into a socket connected to a ring main protected by a 32 amp breaker but the kettle's own plug would always have a 13 amp fuse in it. In fact kettles are normally sold in the UK and Eire with a maximum power of 3000 watts, not 3300, because that only takes 13 amps at 230 volts.

Also it is important to give advice to the end-user never ever to change the plug on the cord of the kettle to a type that can be plugged into a dryer or other higher amperage 240 volt outlet. If they do that, and something goes wrong with the kettle itself, its cord or its plug, there could be a significant fire risk if one of those items should ever get a fault condition which is not a simple short but one that is just a higher-than-normal current draw. That kind of fault condition often happens with an electric kettle because of all the handling it gets and the facts that it has to keep being filled with fresh water and when its boils it emits lots of steam, so the environments they are located in can be quite damp. If such a fault condition occurs, which is not uncommon, then the part that has the fault could easily catch on fire because the too-high-amperage circuit breaker would not necessarily shut off the power. If the kettle was unattended, a house fire could be started.

BrianK: I second the advice that you have added. Some of what you suggested I had already done (resize the breaker and used the British standard outlet and plug), but failed to mention in my comments. As I spent half my life in Ireland and half in the U.S., I am pretty much aware of the advantages and disadvantages of each countries electrical characteristics.

Yet another answer

I have wired up a dozen or so 240v 50hz electric kettles that I have brought back from England for my family. As Martinel correctly points out, most 240v circuits in US homes are likely to have circuit breakers that are much too large to properly protect the kettles. I solve this problem by splicing inline fuse holders into both of the 240v legs of the kettles' cords as close to the plug as possible. Before insulating the connections and going "live", I use an ohm meter to check for any leakage between every connection and the body of the kettle. The connections should be soldered, not merely twisted, and each splice covered with at least two layers of heat-shrink tubing followed by another layer of heat-shrink over both splices. Fuses should match the manufacturer's rating which will be marked on the appliance (typically 15a for British kettles, 10a for New Zealand/Australia.) Install the appropriate size fuses (be sure and leave the fuse-holders accessible, don't cover them with heat-shrink) and you should be protected. In 20 years of doing 240v kettle conversions, I've never blown a fuse or encountered a problem but it is important that you know what you are doing lest you create a potentially fatal safety hazard.

<><><>

As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.