220v wiring types


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Old 05-06-18, 11:09 AM
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220v wiring types

Hi all, I am in the process of building a new cnc control and I need a little more reassurance that I would be wiring correctly. I have an image of how I plan to do the wiring. Would this work on the desktop pc adding a neutral, it says on side of pc that it is 240v3a or 110 6a.
 
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Old 05-06-18, 11:23 AM
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Welcome to the forums.

A very vague question.

We can assume your CNC machine runs on 240vac only.
Are you attempting to use one of those hot wires with a "neutral" to run the control/computer ?

The desktop could be powered off the same 240v but I wouldn't recommend it.
The desktop should be on its own supply circuit....not shared with the machine.
 
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Old 05-07-18, 04:43 AM
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There was a picture of the wiring but it didn't upload. If you read forums on building a cnc machine it's pretty standard to have one power plug and everything on the same circuit. The computer can be used in Europe and has it's own power source made for 240 hence can be used in europe. All I need is a neutral wire so the electricity returns to the transformer on the pole.
 
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Old 05-07-18, 04:47 AM
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Am I thinking correctly? I could connect the one leg of 110v and a neutral to the pc and voila 110v from 220v. Does it work like that?
 
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Old 05-07-18, 05:02 AM
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Am I thinking correctly? I could connect the one leg of 110v and a neutral to the pc
Nominal residential voltages are 120v and 240v. You house is supplied with 240 volts. The 120 is derived from one leg of the 240 volts and the neutral which is actually a center tap on the secondary of the transformer. You would only need a neutral at the CNC if you needed 120 volts. If all is 240v no neutral needed. If you run the computer on 120 volts why not just plug it into a nearby receptacle as suggested by Pete.

All I need is a neutral wire so the electricity returns to the transformer on the pole.
Incorrect. Curent if 240v returns on the opposite leg of the 240 not the neutral.
 
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Old 05-07-18, 05:16 AM
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I feel the same way when people ask about welding lol. I currently have 6-2 wire powering a welding machine ( an outlet). I have to add the neutral wire and a sub panel. 2 breakers inside. 1 goes to the welding plug wired with 2 110v legs and ground, other to cnc 2 110v 1 neutral and a ground. By using just 1 hot leg the neutral and the ground for the pc? Also should I worry about a power supply saying 230v, do I need to add a resistor to step it down 10v?
 
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Old 05-07-18, 05:19 AM
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Thank you trying to help me first off. I'm not understanding why the neutral is sharing the ground in the diagram.
 
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Old 05-07-18, 05:23 AM
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The 130v usually derives from idiots writing the instructions. They are just repeating what they heard or read somewhere. If it is intended for use in the US and is 60Hz not 50Hz there should be no problem.
 
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Old 05-07-18, 05:27 AM
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I'm not understanding why the neutral is sharing the ground in the diagram.
That is a diagram of the transformer powering the house. For safety the neutral is grounded at the pole, the meter and first service panel at the house.
 
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Old 05-07-18, 05:27 AM
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The Big cnc manufacturers do this to make it easy, clean and so noise drains through the same path........from all I've tried to read.
 
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Old 05-07-18, 05:41 AM
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goes to the welding plug wired with 2 110v legs and ground, other to cnc 2 110v (sic)
NO. They are not two 110 legs.
As explained in post #5 they are two 240v legs.
 
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Old 05-07-18, 05:42 AM
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When I put the meter on one leg and the ground I get 120v. Both legs together I get 240.
 
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Old 05-07-18, 05:47 AM
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When I put the meter on one leg and the ground I get 120v
Yes, because the neutral is your grounded conductor but that is not how you measure a 240v supply. You measure it leg to leg..
 
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Old 05-07-18, 07:34 AM
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Voltage is always measured between two places e.g. between two wires.

Typically there are three wires coming to the house from the utility pole. I will refer to them first by color which the lines may or may not have. Measuring from red to white gives about 120 volts. Measuring from black to white gives about 120 volts. Measuring from red to black gives about 240 volts, all regardless of what or how many lights and appliances and tools are being used at the same time.

An appliance that uses "240 volts only" will be supplied using just 2 wires, black and red from above. Current that comes in on black will all return on red. A light that uses 120 volts only will be supplied with white and one of the others. Many appliances have some internal components that use 120 volts and some internal components that use 240 volts. All three wires will supply the appliance and some current will flow on each of the lines: red, white, and black.

By convention and by code in the U.S., one of the three lines, the white, is grounded. It is called "the grounded conductor" for this reason and in U.S., inside the house it must actually have white covering. The other two legs and branches from them may be any color including black but not green (or white). Now that we have designated one line as grounded, the other lines (red and black above) are considered to be hot.

Once in the house, the wiring must include a fourth conductor, technically called the grounding conductor, that is bare or with a green covering, and forming a network following the other wiring. The grounding conductor network is connected to the house grounding system which may include ground rods and/or a water pipe. The network of grounded conductors (referred to as white previously) is connected to the grounding system at just one location, in the panel with the first whole house disconnecting switch or breaker. In a sense, the grounding conductor (we can say ground for short) and the grounded conductor (we use the term neutral) are redundant but ground must not be used as a normal current return (substitute for the neutral) inside the house. For 120 volts (in the U.S.) it is not mandatory to bring along both hot legs so many circuits will have three conductors, hot, neutral, and ground.

Some computers have a little switch on the power supply in back to select 120 volts or 240 volts. If plugged into a receptacle supplying the wrong voltage, the computer will be fried. A few computers will automatically adjust to any voltage between about 120 and about 240 without the need to flip a little switch.

You do not need resistors or transformers or other additional or special equipment when plugging things rated for anywhere from 220 to 250 volts into a receptacle where you measured about 240 volts. Same for 110 to 130 volt equipment into a receptacle where you measured about 120 volts.
 

Last edited by AllanJ; 05-07-18 at 08:08 AM.
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Old 05-08-18, 05:34 AM
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Thank you Allan. I'll post up some pictures of the box when it's wired and ready to get connected.
 
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Old 05-08-18, 09:06 PM
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https://youtu.be/T5zBU14gS6E
what do you think fellas?
 
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Old 05-08-18, 10:01 PM
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The method is correct but the nominal voltages available are wrong. Nominal voltage is is 120 volts and 240 volts 10%. He is also wrong when he refers to the red and black as 110 [sic]. They are the 240v legs.
 

Last edited by ray2047; 05-09-18 at 02:06 AM.
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Old 05-09-18, 08:31 PM
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Nominal voltages in the US are as follows: 120, 208, 240 , 277, 480. 347 and 600 volts can also be found in some industrial settings.

Common electrical systems are:
Single phase 120/240 volts
Three phase 120/240 volts Delta
Three phase 120/208 volts Wye
Three phase 277/480 volts Wye
Three phase 347/600 volts Wye

Voltage is nominal and will vary +/- 10%
 
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Old 05-12-18, 05:09 PM
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Smile

It's coming along ok. Still a work in progress. Feel free to give me any kind of help or pointers.
 
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Old 05-14-18, 05:36 AM
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Smile

What do you think? Hinge and latch are on. Latch is a tad bit catywompas but works very well. Almost time to bolt it up to the wall.
 
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