I want to install USB charging ports in the back of a row 60 lockers.

I want each locker to have 2 usb ports, up to 2 amps per port.

I also want each locker to have its own automatically resetting overload-breaker, so that if one locker gets overloaded, it simply waits a few moments and tries to reset, or it waits until the phone is unplugged, and THEN resets. (I don't want to have to reset it manuallly, and I don't to let it bring the whole system down)


60 Lockers * 2 usb ports * 2 amps per port = 240 amps

Should I get a massive 5 volt power supply to power all the USB ports in parallel with a little DC circuit breaker attached inline with each port?

Should I keep the electricity plain old 110AC and then just literally have an over-the-counter phone charger connected behind each locker?

Should I have a massive 12V DC Power supply to power everything in parallel and then have conceptually a car-charger behind each locker?

Conceptually, what do you think is the best way to do this, for economics, reliability, and not letting an over-load bring down the whole system?

 

Plain old 110AC and then just literally have an over-the-counter phone charger connected behind each locker sounds best if you already have the AC outlets installed. This keeps everything approved for most local electrical code requirements, makes maintenance and upgrades easier and offers redundancy from single point failure of the 'massive' DC supply.

 

Also, remember that (in an ideal case) to get 5VDv at 250A you will need a circuit to convert to DC and a voltage regulator or switch mode supply. There are losses there.

But, you will likely need a dedicated circuit, because you will need around 12A as input to your 5V (or so) transformer. And you will need multiple circuits to convert the AC from the transformer to the DC for the USB hubs. I cannot think of such a circuit that operates at 240A.

 

Something like these?

 

Should I have a massive 12V DC Power supply to power everything in parallel and then have conceptually a car-charger behind each locker?

This is viable and there might be some safety advantages (leading to a cost advantage) to a 12V system near lockers. If not, then I agree with @nsaspook.

One issue you will have to address with any approach other than the 110V+adapters solution is the utilization factor. You can easily calculate the peak current you need, but you will never be at that peak and it would make no sense to build to that capacity. You might only need 30% of whatever the theoretical peak is. But then you need a way to handle a potential overload. These are the same things that utility companies wrestle with.

 

just go with the simple array of cheap AC powered chargers.

The subtle and complex issues that come up trying to roll your own solution are not worth the trouble.

 

Yeah, I'm thinking just plain old outlets and then just simple multi-port usb hub chargers like this one:

https://www.walmart.com/ip/12-Port-...54288&wl11=online&wl12=46167641&wl13=&veh=sem

The lockers don't have any electrical outlets directly next to them.

I'm not exactly sure what passes electrical code. I don't know if having a bunch of usb ports mounted into metal lockers passes code or not. I should probably talk to an electrician.

I also need to decide how to mount the usb port receptacles themselves into the sheet metal.

 

I want to install USB charging ports in the back of a row 60 lockers.

I want each locker to have 2 usb ports, up to 2 amps per port.

I also want each locker to have its own automatically resetting overload-breaker, so that if one locker gets overloaded, it simply waits a few moments and tries to reset, or it waits until the phone is unplugged, and THEN resets. (I don't want to have to reset it manuallly, and I don't to let it bring the whole system down)


60 Lockers * 2 usb ports * 2 amps per port = 240 amps

Should I get a massive 5 volt power supply to power all the USB ports in parallel with a little DC circuit breaker attached inline with each port?

Should I keep the electricity plain old 110AC and then just literally have an over-the-counter phone charger connected behind each locker?

Should I have a massive 12V DC Power supply to power everything in parallel and then have conceptually a car-charger behind each locker?

Conceptually, what do you think is the best way to do this, for economics, reliability, and not letting an over-load bring down the whole system?

Use individual chargers. Buy a few extra. Have an electrician add outlets as needed.

 

I don't think outlets in lockers will fly with an inspector. Maybe.

 

If the low voltage USB ports could be inside the locker but the high voltage part outside, in a sealed cage, there shouldn't be any wiring code issue.

 

If the low voltage USB ports could be inside the locker but the high voltage part outside, in a sealed cage, there shouldn't be any wiring code issue.

I would think that multiple low power supplies would be needed. All sixty lockers off one supply presents a challenge. If the TS could break it into several strings, each with its own supply and then run, let's say 9V to each locker, where there is a local regulator and charging circuit, it might be feasible.

 

Having seen the way people chuck things into lockers, I reckon the ports/modules would need to be well protected from physical damage/abuse.

 

Having seen the way people chuck things into lockers, I reckon the ports/modules would need to be well protected from physical damage/abuse.

I agree. I think mounting it in the "roof" of the locker would probably be the safest.

 

My plan as of now is to have plain old 110v power strips above the lockers, then a plain old off the shelf 12-port USB charging hub every few rows.

Planning to drill a hole in the back right corner of each locker from the very top all the way down, then slide plastic conduit down from the top. The plastic conduit will have a slice in one side so that I can stick the usb cables inside and then have one usb cable pop-out of the conduit in the top right corner of each locker.

Is electric code completely concrete, like for example "You cannot have more tan 3vdc near metal lockers" or is it more vague like whatever the inspector thinks is reasonable and safe?