Voltage, plugs and adapters in the Triple Frontier

Direct answer: In Foz do Iguaçu the standard outlet is 127 V at 60 Hz, with three round pins. In Puerto Iguazú and Ciudad del Este the grid is 220 V at 50 Hz, with different plug shapes. Dual-voltage phone and laptop chargers only need an adapter; single-voltage hair dryers and flat irons may need a converter.

The three sides in one table

Foz do Iguaçu: 127 V at the outlet, 220 V in some spots

In Brazil, voltage varies from city to city. Foz is served by Copel, and the utility's supply standard provides 127 V between phase and neutral and 220 V between two phases, always at 60 Hz across its service area. In practice, the regular outlet in hotels, apartments and restaurants delivers 127 V. The 220 V supply shows up at dedicated points such as electric showers, air conditioners and, sometimes, an outlet labeled "220 V" in the room.

Check before you plug in: hotels often label the voltage next to the outlet. If there is no label, ask at the front desk.

The outlet follows the Brazilian NBR 14136 standard, mandatory since 2010 for plugs and outlets sold in the country: three round pins, with the middle one as ground. There are two pin sizes: 4 mm (10 A, most devices) and 4.8 mm (20 A, high-draw appliances).

Puerto Iguazú: 220 V and flat pins

Argentina supplies 220 V to homes, as stated in the country's own regulation on electrical equipment, at 50 Hz. Outlets follow the IRAM 2071 (outlet) and IRAM 2073 (plug) standards: two angled flat pins plus a ground pin, the shape known internationally as Type I. Some Argentine outlets are dual and also take the thin two-round-pin plug, but you can't count on that in every room.

If you are coming from Brazil, a three-round-pin plug will not fit a standard Argentine outlet. Argentine visitors in Foz have the opposite problem: flat-pin plugs don't go into Brazilian outlets. Both sides need an adapter.

Ciudad del Este: 220 V and every kind of outlet

ANDE, Paraguay's state power company, defines low voltage as 380 V between phases and 380/√3 V (about 220 V) single-phase, and the Paraguayan grid runs at 50 Hz (that is why Itaipu has a 50 Hz sector for Paraguay and a 60 Hz sector for Brazil). Outlet shape is the weak spot: in practice Paraguay has no single standard. You'll find outlets for two flat pins, two round pins and three pins. In 2022 Paraguay's standards body, INTN, released a standard based on the international IEC 60906-1, but compliance is voluntary. A universal adapter takes care of it.

Adapter or converter?

Mixing them up is what fries devices.

• An adapter only changes the plug shape. It does not touch the voltage. It works for anything dual-voltage.
• A converter (or transformer) changes the voltage. It only makes sense for single-voltage devices.

To check, read the label or the power brick. If it says "100-240 V, 50/60 Hz", it is dual-voltage and works in all three countries with just an adapter. That covers almost every phone, laptop and camera charger.

Heating appliances are the ones to watch: hair dryers, flat irons, curling irons, older shavers, electric kettles. Many are single-voltage or have a selector switch.

• A 127 V-only device plugged into 220 V (in Puerto Iguazú or Ciudad del Este): it burns out. Use the selector switch if it has one, or a converter.
• A 220 V-only device plugged into 127 V (in Foz): it usually won't burn out, but it runs weak. The dryer blows lukewarm air and the flat iron doesn't heat properly. Use the hotel's 220 V outlet if there is one, or bring a dual-voltage model.

A charger marked 50/60 Hz won't notice the change in frequency.

Where to buy an adapter

A universal adapter with USB ports is cheap and easy to find at electrical supply stores, supermarkets and electronics shops on all three sides. Ciudad del Este has plenty of options, so check the build quality: when Paraguay's 2022 standard was announced, local press reported on cheap plugs that overheat and melt. Choose one with a solid body and firmly fixed pins, and avoid running a powerful hair dryer through a flimsy adapter.

If you plan to buy electronics across the bridge, confirm the power supply is dual-voltage before paying. More in buying a phone or iPhone in Paraguay and the Paraguay shopping allowance.

Before you go

Read the label on each device, set aside anything single-voltage and pack the adapter in your carry-on. It belongs on the list of what to pack for Iguazu Falls, next to your SIM: see SIM cards and internet in the Triple Frontier to avoid roaming by accident.