I am building 3 large computers each running 3 1300w power supplies. I purchased the units and I can't return them only to find them in Chinese/AU Power. The label reads "180v-264v 50-60Hz 20/10A" In my house, I ran 3 Romex 6/3 wires connected to 60A breakers. My intention was to hook 3 power supplies to each line. I ran each of these lines to a disconnect box. My problem is the power supplies have 3 wires. Brown hot, Blue natural, and Green/yellow ground. I have looked into step converters but I don't see any type of product that would let me take the 220v line I have run to the 180-264. Any suggestions how to proceed or where to find what I need?
Electrical – Chinese Power Supply 180-260v on US 220v Electric
electrical
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It's referring to the electrical service supplying the house. Most homes in the US are supplied by a single phase service, which is often described as a 120/240 Volt system. If your house is supplied by a three phase system, it could be a 120/208 Volt system.
In both these cases you'll be able to install the equipment you have.
NEMA 14 devices are four wire grounding devices. Which means they'll require two ungrounded "hot" conductors (X,Y), one grounded "neutral" conductor (W), and one grounding conductor (G). When installed on a single phase 120/240 volt circuit, NEMA 14 devices can supply 120 and/or 240 volt loads. A NEMA 14-30 device is designed to supply 30 ampere equipment.
The circuit will require a 30 ampere double pole breaker, and four at least 10 AWG copper conductors. You'll connect one ungrounded "hot" conductor to each of the X and Y terminals. The grounded "neutral" conductor goes to the W terminal. And the grounding conductor connects to the G terminal.
What size are the wires? A 40 AMP circuit is probably 8 or 10 AWG, neither of which will likely fit in the terminals of a 20 ampere receptacle. Which means you'll have to use a 12 AWG pigtail, to attach the receptacle to the circuit.
Aside from that, you've got it about right.
- Remove the existing receptacle.
- Install a new box.
- Use properly sized twist-on wire connectors to attach a 12 AWG pigtail to one of the ungrounded (hot), the grounded (neutral), and the grounding conductors.
- Use a properly sized twist-on wire connector to cap the extra ungrounded (hot) conductor.
- Remove the double pole 40 ampere breaker.
- Install a single pole 20 ampere breaker.
- Connect one of the ungrounded (hot) conductors (the one attached to the receptacle), to the new breaker.
- Use a properly sized twist-on wire connector to cap the extra ungrounded (hot) conductor.
- Install a plate to cover the empty hole in the panel cover (that was created by removing the double pole breaker).
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Best Answer
There are several issues here. But the good news is, you erred on the side of overdesign, so it'll be easy to put it right, and you'll wind up with a fair bit of spare capacity. For instance, running 6/3 was a great move. It didn't add much cost and it gave you versatility you can put to good use.
That power supply
The power supply is rated at 1300W output. One aspect of its cheap Cheeseness and lack of UL listing is that it doesn't have a nameplate power rating, or the power it needs from the power grid. This differs from output rating by a) power supply efficiency, and b) power factor. Skipping the gory details, I'm going to SWAG-guess the nameplate at 1800 VA. The numbers work out reasonably well if I do that.
(feel free to google VA and how it differs from Watts).
Aside from that "reality check", this will be a continuous load so we must do a derate of 125%. That means we need to provision a circuit for 125% of 1800 VA, or 2250 VA.
Your 60A circuit has 240V x 60A = 14,400 VA. You won't have any trouble provisioning three 2250W loads on the circuit. In fact, you could get six.
Powering the units, and neutral
RedGrittyBrick points out a serious issue. These units are made to be connected to hot and neutral. In USA 240V power, there's no neutral, it's hot and hot. The neutral on the power supply would need to be insulated to tolerate being 120V from ground, and it may not be. If only the factory could advise you! Regardless, here's how to fix it.
They make "step-up, step-down" transformers. You supply 120V at 20A (2400 VA) to the transformer. It passes the neutral straight through (so that is satisfied). Then it doubles the voltage of the "hot" wire, giving you exactly the right thing: 240V and neutral.
Supplying 120V is possible because you used /3 cable.
Power distribution off 60A
You can't just hotwire all 3 power supplies to a 60A main, especially when they're cheap units. Putting a 1800W unit on a 14,400W circuit breaker is nearly worthless, because the trip point (14,400W) is so very much higher than the rating of the power supply (1800W). You need more sensible breaker sizes.
How to safely split up that 60A supply:
PDU. Your first option to distribute power is a PDU, which is computer equipment made to sit on the bottom of a rack, take a fat power connection, and distribute it to individual servers in the rack, with sensible circuit protection. However PDUs are expensive, and subpanels are cheap.
A quality QO panel is about $45, a cheapie BR $22, breakers are $5 or $9 for 240V types.
Subpanel. Normally I recommend the biggest subpanel you can afford. But in this case, there's no use for more than 8-13 spaces (it's rated current must be at least 60A). And then, you fit breakers like this.
Note in the 120V example, you really have to watch breaker placement for the servers. Place the server breakers in pairs side by side, just like 2-pole breakers. Do not put the 6 server breakers in the top 3 rows. The aux circuit is for small loads like monitors, switches etc.
Don't parallel. Use three subpanels.
Neutral and ground must be separated in the subpanel, so add an accessory ground bar ($5) and remove the green screw on the neutral bar to unground it. This makes 120V available.