# Different phases on different components

Say I have a typical wiring in my room where in I have two computers (A and B). A is a power hungry machine whereas B is simply a laptop.

Due to various reasons I decided to get a power board with 3 electrical phases in it. So my main AC board where you plug in the computer power cable has 3 sockets each on different phases namely Red Yellow and Blue respectively. This board is only available to the computer A.

I connect my laptop B to another AC board which runs on the Red phase.

Now if I connect my main pc A to draw power from AC socket with phase other than Red which is Yellow or Blue and let the laptop run on Red phase, my questions are as under.

I want to clarify here that both the systems need to be connected to each other using ethernet.

• Would I blow my whole setup if I connect the two systems on different phases by connecting them using an ethernet cable?
• Is this setup correct and will work or all devices in a network should be connected via a single phase.

Would I blow my whole setup if I connect the two systems on different phases by connecting them using an Ethernet cable?

No. Computers have isolating power supplies. The logic circuits (motherboard, etc) are not directly connected to the mains.

Isolation is provided by a transformer - usually as part of a switched mode power supply.

Figure 1. A simplified schematic of a switched-mode power supply (SMPS). Source: SMPS.us.

Note the transformer in the DC-DC converter section on the right. The transformer symbol represents two coils wound on a ferrite cord. The windings are insulated from each other and so there is no direct connection between the AC line on the left and the DC outputs on the right.

Is this setup correct and will work or all devices in a network should be connected via a single phase.

All devices will be fine for the reasons given above.

• You mean to say that even if I connect them using Ethernet connection it is safe? – LoneWOLFs Aug 12 '17 at 12:01
• Yes. Think about it a bit. All your computers are earthed or can be via USB connected devices or audio circuits. The network cards are the same. If this was not the case you could receive a shock if you touched the chassis on a computer. – Transistor Aug 12 '17 at 12:13
• In addition, Ethernet connections are also transformer-coupled. So, even when the device has a transformerless power supply, the two circuits are still insulated from each other. – Janka Aug 12 '17 at 12:25
• @Janka: Thanks. I was going to mention that but I couldn't find a good, simple illustration. – Transistor Aug 12 '17 at 12:32
• @LoneWOLFs yes, ethernet has its own isolation. – Jeroen3 Aug 12 '17 at 13:30