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I assume we are talking about 120/240V service somewhere in the US, and that you are using copper wire! You must consult the NEC (National Electric Code) or other code your municipality uses. It must be the year of issue that your municipality has adopted AS AMMENDED by that municipality. Many cities do not adopt the codes as-is, they change things here and there. Get a copy, or hire someone who knows this stuff. Using the plain 2005 NEC, I would go to article 230 - Services. It tells me the size of the grounded conductor depends on the size of the ungrounded service entrance conductors, so I have to know that first. 230.42A tells me the ungrounded conductors are sized according to 310.15, so I go to article 310, Conductors and look at table 310.15(B)(C). It says your 400 Amp service will use 400 kcmil wire for the ungrounded conductors. Back to article 230. Paragraph 230.42C says to size the grounded conductor according to 250.24C, so I turn over to article 250, Grounding. 250.24C sends me to table 250.66. Table 250.66 says that for service entrance conductors over 350 kcmil and less than 600 kcmil, the grounded conductor would be 1/0. There are a few exceptions and circumstances that could change the answer, but you get the idea. As you can see, this is not trivial, and mistakes will be costly. Hire a pro to do the calcs for you. Unless this is a homework or test question. In that case, you're welcome... <><><> If you're asking this question you shouldn't be installing an electrical service. Asking this type of question usually means you aren't ready to do this yourself. Study some electrical material and the National Electrical Code, or call a professional electrician. If someone were to give you an answer here, you might attempt to do something you shouldn't be doing, and that may cost someone a shock, a home fire, or their life. IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS. If you do this work yourself, always turn off the power
at the breaker box/fuse panel BEFORE you attempt to do any work
AND
always use an electricians test meter having metal-tipped probes
(not a simple proximity voltage indicator)
to insure the circuit is, in fact, de-energized.
What else can I help you with?
How can you get a 240V single-phase power from a 120V 3-phase service?
First of all there is no common three phase 120 volt service. There is in North America a three wire 120/240 volt single phase service. That being said, if you want to change a 120 volt source to 240 volts it must be done with a transformer. Its classification is a step up transformer. The primary side of the transformer H1 - H2 will be connected to the 120 volts. The secondary side of the transformer X1 - X2 will be connected to the 240 volt load. The transformer is sized by the current required by the 240 volt load.
What is the minimum voltage of US household mains supply?
240, single phase for houses208 3 phase for comerical property, can be single phase.480 volt for industrial property or 660 volts,all 60 HzUSA calls it single phase but there is actually 2 hot leads coming into the house with a natural and a ground.It is actually two 120 volt 'hots' which are 180° out of phase from each other. Voltage between either of these and ground will be 120 V. Voltage between the two hots is 240 volts. It is single phase because it is pulled off one of the phases from 3-phase, then a center tapped transformer gives the two 'opposite phases' (ground/neutral is off the center tap)In Vietnam we have 440 volts, 3 phase, 50 Hz on the poles.They bring in one hot wire and one ground. I call this single phase,It equals 220 volts in your house.
How do you determine a 3 phase motor and each winding?
To see if the motor is three phase or single phase look at the motor's nameplate. There it will tell you what the voltage needs to be and what system phase the motor needs to be connected to operate properly.
How many wires in a single phase motor?
There should be 2 or 3 wires. A hot, a neutral and sometimes a ground.
What wire size for 100 amp single phase 3 wire commercial service?
2 copper
what is the cheapest electric supply cost single phase or 3 phase?
The cheapest service to construct is a single phase service. A three phase service requires more equipment and materials to complete a service.
How many single phase can you run on a 100amp 3 phase?
You can divide a three phase service into (3) single phase circuits providing you have a 4th neutral wire.
What is the need of single phase to three phase conversion?
There is no need of single phase to three phase conversions. Both service types are available from the local utility company.
How can you determine what electric service you have?
It depends on where you live in the world. In North America there are two types of services, single phase and three phase. Single phase is usually used in homes and three phase is used for commercial and industrial installations. Single phase home services are 120/240 volts and can be identified by there being three wires coming to your home and into the service head drop. Three phase services are now usually a wye connection and are identified by there being four wires that go into the service head. These voltages could be 120/208, 277/480 and 347/600.
How many earth wires are required for single phase motor?
There is only one ground wire needed on any motor, single or three phase.
How many wires come in from the weather head?
If single phase - 2 wire service > two wires If single phase - 3 wire service > three wires If three phase - 3 wire service > three wires If three phase - 4 wire service > four wires US residential service is usually single phase 3 wire service: Two hots and neutral.
How can I wire a 240 V single-phase outlet from a commercal building with 3-phase service 4- wire?
A three phase four wire commercial distribution service will not give you 240 volts. The nearest voltage you can get is 208 volts. It is a wye connection which gives you 208 volts between the three legs and 120 volt between any of the three legs and ground. This ground point is the systems neutral point.
How can you determine if a electric motor is 1 phase or 3 phase if there is no name plate?
Check the motor's terminal box. If there are three service input cables - such as red, yellow and blue - plus an earth wire, then it is a three phase motor. If there are only two wires plus an earth wire, then it is single phase.
What phase are residential air conditioner units?
Most standard residential service is single phase. Therefore, I would say most all residential A/C units are single phase.
How can you get 3 phase connection?
If you have single phase now, you have two options. One, is to install a three phase service or Two, install a roto phase device.
How do you know if the single line is single phase or 3 phase?
If the single line is compared to another single line and the voltage that you need is correct then you are looking as a singly phase supply. The electrical classification of single phase is that any two legs of a three phase supply can be called single phase. Look on the nameplate of the distribution panel. There it will state what the panel is, either single phase or three phase. Look at where the distribution enters the building from the utility supply. If there are three insulated conductors (red, black and blue) wrapped around a bare aluminium messenger wire it is a three phase wye connection service. If you see two black insulated conductors wrapped around a bare aluminium messenger it is a single phase service.
What are the advantages of using single phase electricity?
Simple hookups to devices you wish to power (2 wires and ground). Most household common devices use single phase.
