Quick Answer: Ten ports do not mean ten times the current. A 60 W supply shared across ten ports gives 12 A in total at 5 V, or 1,2 A each when every port is loaded, and one 60 W USB PD laptop takes the whole budget and leaves nothing for the other nine. Size the supply at 1,2 to 1,5 times the measured sum, insist on a UL 62368-1 listing, and expect 10 to 15 W of heat inside a closed cabinet.
The purchase decision is a power calculation, not a port count. Start from what will be plugged in, add the cables, then choose a supply with headroom. A station that browns out at 8 pm is a supply that was sized from the label rather than from the load.
The arithmetic that decides the supply
Sum the ports, then derate
At 5 V, one ampere is 5 W. Ten ports at 2,4 A each would need 24 A and 120 W if every port ran flat out, which is rare but not impossible on a tablet trolley. Size the supply at 1,2 times the realistic sum and never below the sum of the rated port currents if all ports can be occupied at once.
Shared or dedicated per port
A shared rail divides its total between ports, so the tenth device charges slower than the first. Dedicated converters give every port its full rating and cost more. For phones overnight, shared is fine; for tablets or laptops in a shift, dedicated converters are the difference between a full battery and 40 per cent.
Matching layout to the load
| Port layout | Total output | Max per port | Typical load |
|---|
| 10 x USB-A, 60 W | 5 V, 12 A | 1,2 A average | Phones overnight |
| 10 x USB-A, 120 W | 5 V, 24 A | 2,4 A each | Tablets, shared rail |
| 8 x USB-A + 2 x USB-C, 120 W | 5 V, 24 A | 60 W PD single | One laptop plus phones |
| 2 x USB-C PD 100 W + 6 x USB-A, 200 W | 5 V, 40 A | 100 W PD single | Two laptops plus phones |
| 10 x USB-C PD 30 W, 300 W | 5 V, 60 A | 30 W each | Ten tablets at full rate |
Cable gauge decides what arrives
A 28 AWG charging lead has about 0,213 ohm per metre, so a 1 m lead carrying 2,4 A loses 1,0 V in the pair and the device sees 4,0 V instead of 5 V. At 3 A the same lead loses 1,3 V and most devices drop to a slow charge. Use 20 AWG or 22 AWG leads above 2 A, and note that a usb-c to usb-a cable is usually rated 2,4 A even when the port can do 3 A. The differences between the two plug types are set out in usb a vs usb c, and the current rating matters more than the plug shape on a ten port station.
USB PD and PPS negotiation
A USB-C port rated 60 W only delivers 20 V at 3 A after the device and the port agree a contract. If the device asks for 9 V at 3 A and the station only offers 5 V, it charges at 5 V and the port looks faulty. Confirm the station supports the profiles the devices request; usb pd pps matters for phones that ramp voltage in 20 mV steps.
Heat, listing and mounting
A 120 W station dissipating 12 W inside a closed steel cabinet will reach 50 C above ambient. Mount it with 50 mm of clearance on every side, or choose a unit with a metal case and vents. Check the case for a UL 62368-1 mark and a separate listing for the power supply; the CE mark alone is not a safety listing.
Practical scenarios
- Situation: a school trolley holds 10 tablets at 2,4 A each. That is 24 A and 120 W; a 60 W station charges five at a time and the rest sit idle, so specify 120 W and a 20 AWG lead per device.
- Situation: a reception desk runs 10 phones plus one 60 W laptop. Use a station with two USB-C PD ports, keep the laptop on its own converter and leave the shared rail to the phones.
- Situation: a wall box has no socket for a second supply. Feed one 200 W station through a 16 AWG extension of 3 m and check the volt drop stays under 0,3 V at 40 A, which is not achievable – shorten the run instead.
- Situation: a station resets when the cleaner plugs in a vacuum on the same circuit. Move it to a circuit with 20 A capacity and confirm the supply input range before blaming the ports.
FAQ
Can a 60 W station charge ten tablets at once?
Only slowly. Sixty watts divided ten ways is 6 W per port, about 1,2 A at 5 V, so a 10 000 mAh tablet takes roughly six hours. Size the supply from the number of devices that must be full by morning.
Does a higher wattage port damage a phone?
No. USB charging is negotiated, and a phone takes only what it asks for. A 100 W port feeding a phone that requests 18 W delivers 18 W. The risk is a non-compliant supply, not a large one.
Are all USB-C cables suitable for 60 W?
No. A cable must be rated 3 A or 5 A and carry the correct electronic marking. A thin lead rated 2,4 A limits the port to 12 W whatever the station can deliver, and the device simply charges slowly with no error message.
