Why hair dryers fail abroad
A heating element is a fixed resistance with no regulation of any kind. That is not a shortcoming — it is the entire design. It also means the supply voltage decides the power, and the relationship is a square, not a ratio.
P = V² / R, and why that is unforgiving
Put a fixed resistance across a supply and the power it dissipates is the voltage squared, divided by the resistance. Double the voltage and you do not get twice the power. You get four times it.
Take an American hair dryer: 120 V, 1500 W. That fixes the element at about 9.6 Ω. Plug it into a 230 V supply through nothing but a shape adapter and it will try to dissipate
230² ÷ 9.6 Ω ≈ 5,510 W — 3.7× what it was built for.
Nothing in the device limits that. The element glows far past its design temperature, the plastic housing around it softens, and the thermal cut-out opens — permanently, in most units, because it is a one-shot fuse rather than a resettable switch. The good outcome is that the fuse does its job. The bad one involves the smell of hot plastic in a hotel bathroom.
The other direction is harmless, and useless
Reverse it. A European dryer, 230 V and 2000 W, has an element of about 26.4 Ω. On a 120 V supply:
120² ÷ 26.4 Ω ≈ 544 W — about 27% of rated power.
Nothing is damaged. Nothing is at risk. It simply blows barely-warm air very slowly, and the motor turns lazily too. This is a genuinely different outcome from the first case, and it is the one most guides collapse into the same warning. We give it its own verdict — safe, but it won't work properly — because "don't take it" and "take it, it just won't be much use" are different pieces of advice.
Why a converter does not rescue this
Because of the numbers. Here is what our device table records these things actually drawing:
| Device | Typical draw | Needs earth |
|---|---|---|
| Full-size steam iron | 1000–2400 W | yes |
| Hair dryer | 1200–2000 W | no |
| Handheld clothes steamer | 800–1600 W | yes |
| Travel kettle | 600–1000 W | yes |
| Travel iron | 400–1000 W | yes |
| Baby bottle warmer | 100–500 W | yes |
| Hair straightener | 30–250 W | no |
| Curling iron or tong | 25–200 W | no |
| Electric blanket | 60–200 W | no |
A travel converter rated "2000 W" is almost always rated for minutes, not for continuous duty, and it delivers a chopped waveform rather than a sine wave. A transformer that will genuinely carry 1800 W continuously exists, weighs several kilograms, and costs more than the dryer. The difference between those two products is the single most useful thing to understand before buying either.
Why your charger is fine and this is not
A phone charger is not a resistance. It is a switch-mode power supply: it rectifies whatever arrives, chops it at high frequency, and regulates the output to 5 V regardless. Feed it 100 V or 240 V and it draws whatever current it needs to deliver the same watts. That is why the same brick works everywhere, and why none of the arithmetic above applies to it.
The dividing line is not "expensive versus cheap" or "modern versus old". It is whether the thing has a regulator in it or a wire that gets hot.
What to actually do
- Hair dryers: essentially every hotel above hostel level has one on the wall. This is the rare case where the answer is genuinely "don't bring it".
- Straighteners and tongs: lower wattage, and dual-voltage models are common and inexpensive. Buy one of those rather than a converter.
- Travel kettles and irons: the same physics, plus most of them need an earth. Check the earth survives your adapter.
Run your trip through the tool and it will sort everything you own into what travels, what needs an adapter, and what to leave behind.