Why are power tools made in 110V and 240V?

[lavenders19]

... and are there any advantages to having a 110V even though you have to **** about with a transformer.

[manatbandq]

The transformers are centre tapped so that the maximum voltage from ground is 55V as against 240V with a normal domestic tool. This is considerably safer.

MBQ

[owdman]

Safety - no risk of shock in risky situations such as on building sites working off metal ladders, near water, high risk of cable damage due to presence of cutting tools or other causes. Not so important in quiet domestic situations.

cheers

Jacob

[Tim S]

Because the 110V transformers are actually 55-0-55 centre tapped to earth, so the most likely exposure you'll get on a wet building site is 55V, which is not totally safe, but way better than 240V.

Cheers

Tim

[.]

as the other have said, safety.

BUT (and there's always a but) many moons ago, someone I know was told to put a plug on a 110v item and test it. so he put a plug on it, plugged it in and it exploded in his face and damaged 80% of his eyesight. he wasn't told it was 110v and there was no readily identifying marks on it.

the firm (very famous) eventually accepted liability and paid out a significant sum in compo as a young trainee should not have been doing that sort of thing unsupervised.

[lavenders19]

I take it then that there are no advantages on a like for like basis of tools lasting longer etc or being able to take more stick.

[Doctor Drivel]

There is no regs saying you need 110v on sites. It came about in the 1950s.

240v with RCDs is just as safe, or even safer. Times have moved on and 110v on sites should cast to history. BTW, it is not the 110v as in the USA, which is 110v, not 55-0-55. I suppose we could have 120-0-120 transformers, as the tools can be used anywhere. I know some contractor who will not do site work as it would mean spending many 1000s on 110v tools.

[Andy Hall]

It does also allow you to buy some kinds of tool in/from the U.S., often at substantially lower prices than in Europe.

Among these are cordless tools with a charger - the charger will operate from an autotransformer or site transformer, and tools with a universal motor (i.e. with brushes) which will work from a site transformer. Machines with induction motors may well not, but this is due to their being designed for 60Hz operation as opposed to any voltage issue.

[John Rumm]

The tools will run from higher current and hence need heavier windings on the motors. This may make them a little more resiliant, but by the same token they are more succceptable to voltage drop on the supply, and also likely to dissapate more heat internally (due to the extra current).

(you could argue that you only tend to find 110V versions of the better tools in the first place - so there is less chance of buying a cheap and very nasty 110V tool)

[manatbandq]

Depends what you mean. A 10% drop in the supply is a 10% drop whatever the nominal voltage and leads to a 10% drop in power.

Power = I*V, double the current and halve the voltage and the power dissipated remains the same.

MBQ

[Doctor Drivel]

Yep.

[Weatherlawyer]

240/ne 230 european volt tools are substantially cheaper in Britain than the 110 equivalent because only a few people buy 110 v equiptment here. The number is dropping as battery tools take over and sites supply specific tools not normally required by agency workers.

Agency tradesmen can demand the site provide SDS drills, 110 planers and circular saws. Smaller sites will usually allow 240 volt tools if they have to, even though most will carp. Larger sites have too many middlemen to do so. And they want all their safety rules followed regardless of anything else.

It is a PITA sorting out wiring and transformers all the time with

110v. They weigh a ton too which adds to the travel expense.

[Doctor Drivel]

What amazes me, is that is there is just no need for it.

[Dave Plowman (News)]

Most of the 'contractors' you seem to quote use DIY shed tools, so no surprise there.

[Doctor Drivel]

Isn't it sad. The senility has really set in. He has invented some contractors now. Sad, very sad. Year ago he would have been locked up.

[Weatherlawyer]

Not now no, maybe but I can remember the good old days.

[Fred]

In the US the 110V is generated by a transformer, often in the home and fed with a much higher voltage which I thought was 2.2KV though not sure. The transformer is tapped to give a nominal 55-0-55 wrt ground potential. Forgive me if I'm wrong. IANAE

[Doctor Drivel]

Now they are the bad old days, and having 110v is needless. Also many tools are double insulated as well as having RCDs. Why 110V? Madness.

[John Rumm]

Done the same way here - 240V is usually steped down from a 11kV feed.

IIUC, the US system typically uses 110 - 0 - 110 centre tapped, and both lives are taken to the property. That way thay can use both to get a

220V supply for higher power fixed appliances like tumble driers etc.

[John Rumm]

Yes but voltage drop will be an absolute value for a given length of wire etc and hence will represent double the difference in percentage terms since the voltage is halved. (i.e. it is not a function of the supply voltage, only I and R)

This is hence why you have to take far more care with voltage drop on

12V lighting systems if you are not to see an obvious difference in brightness between lamp fittings.

Power dissipated for a given resistance of motor winding will be I^2*R hence rises in proportion ot the square of the current.

The two points I make above have different implications. Voltage drop on a tool using a universal motor simply results in lower power output in proportion to the percentage drop of the voltage. On a tool with an induction motor however, it means higher winding current and hence possibility of damage.

The dissipation issue comes into play even without any appreciable voltage drop issue. One of the reasons house fires caused by electrical installs are far more common in the US than here.