Question: What is the proper way to fuse and switch a power supply consisting of a bunch of SMPS like the following:

[![smps power supply](https://i.stack.imgur.com/qd2vI.jpg)](https://i.stack.imgur.com/qd2vI.jpg)

There would be up to 5 separate output voltages. The outputs shown are about 35W each. Other outputs would be less.

So currently I have a mockup that has a single fuse and a single switch on the AC load line.

Is this safe?

Would it be better to use a 2 pole switch to switch in both load an neutral? Why?

Should I fuse each SMPS separately? If yes, why and where?

Points labelled A, B, C and D are potential locations for reference.

Answer: 
> 
> So currently I have a mock-up that has a single fuse and a single switch on the AC load line. Is this safe?
> 
> 
> 

The majority of devices found in the home or office are wired this way and there are few issues. The problem is that if you live in a land of non-polarised mains plugs which when reversed, can make the non-switched wire live, then the internal circuitry remains live even when the switch is off. A table lamp, for example, has a single-pole swtich and the terminals are exposed when the lamp is removed. Your setup should be much safer if boxed up properly.

> 
> Would it be better to use a 2 pole switch to switch in both load an neutral? Why?
> 
> 
> 

When the switch is off both lines are cut and the circuit is completely dead.

> 
> Should I fuse each SMPS separately? If yes, why and where?
> 
> 
> 

Check your SMPS and you should find that there is a fuse on the mains side of each. The main fuse protects the wiring inside your unit in the event of a fault. Your SMPS units will supply a total of about 100 W so will draw a max of 130 to 150 W fully loaded. In 110 V land this will be about 1.5 A and in 230 V land it will be less than 1 A. Use a 2 A or 1 A fuse as appropriate in the common live line, point 'A' as you have correctly shown. This will limit any fault current to a much lower and safer value than your mains wiring can provide.
I would use a single switch and fuse as you have shown, particularly if the supplies have internal fuses.

Whether the individual supplies should be switched will depend on the application.