All About Circuits Forum hot common????
 Register Blogs FAQ Members List Today's Posts Search Today's Posts Mark Forums Read

 General Electronics Chat Discussion forum for general chat about anything electronics related, including asking questions about material in the All About Circuits E-book, Worksheets, and Videos.

#1
08-27-2006, 01:14 AM
 coolbreeze New Member Join Date: Aug 2006 Posts: 1
hot common????

my boss and i have been having a disagreement, about the common wire in a three wire split phase 240 a.c. circuit. the argument is , first , that the neutral wire and common wire is one in the same.. second, that this wire is only used for return voltage and is never a live wire... he says that is he taks a voltage reading from the wires connecting to the capacitor wich are ( fan , commmon , compressor) he says if he takes a voltage reading from one of the legs and the common wire he gets 240 volts, therfore he believes the common is a hot wire..
can you please explain this to me .. and also explain that the common and neutral wire is the same thing... thanks.......
#2
08-27-2006, 01:44 AM
 beenthere Senior Member Join Date: Apr 2004 Location: Missouri, USA (GMT -6) Posts: 15,815 Blog Entries: 10

Hi,

AC common and neutral are equivalent terms. It is not live. It is for the return of current in the circuit.

A voltmeter measures a voltage difference between two points. If you see 240 volts between any phase and neutral, then it follows that the neutral is at ground potential. If it were live, there would be a lesser voltage differnce between it and the voltage leg being metered. If you have an earth ground close by, place the meter leads on it and neutral, and see what voltage shows up.
#3
08-28-2006, 05:40 AM
 Joe S. Junior Member Join Date: Aug 2006 Posts: 10
May I intrude?

It has some application here.
If the neutral is carrying current then you need a safety ground, example a split phase welder might have a 120v wire feeder attachment, then it requires a safety ground, whereas a compressor may not have an active neutral and likely would not, but if that neutral is carrying load then a seperate safety ground is required. same deal with 3 phase, it's no longer permitted to run 3 wire 3 phase here anymore. Bottom line error in the favor of safety, money is replaceable, lives are not.

 Tags common, hot

 Related Site Pages Section Title Worksheet Delta and Wye 3-phase circuits Worksheet Multi-stage transistor amplifiers Worksheet AC motor theory Textbook Three-phase power systems : Polyphase Ac Circuits Textbook Single-phase power systems : Polyphase Ac Circuits Textbook Special transformers and applications : Transformers Worksheet Safety grounding Textbook Wiring Color Codes : Color Codes Textbook Safe circuit design : Electrical Safety Textbook Safe meter usage : Electrical Safety

 Similar Threads Thread Thread Starter Forum Replies Last Post Stanly General Electronics Chat 23 03-30-2014 02:07 PM Joanna91 Homework Help 11 06-19-2012 10:31 PM donut General Electronics Chat 3 06-11-2012 03:44 PM zorbzz The Projects Forum 9 04-28-2010 05:06 AM nirvanaguy Homework Help 1 03-24-2010 12:01 AM

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Electronics Forums     General Electronics Chat     The Projects Forum     Homework Help     Electronics Resources Software, Microcomputing, and Communications Forums     Programmer's Corner     Embedded Systems and Microcontrollers     Computing and Networks     Radio and Communications Circuits and Projects     The Completed Projects Collection Abstract Forums     Math     Physics     General Science All About Circuits Commmunity Forums     Off-Topic     The Flea Market     Feedback and Suggestions

All times are GMT. The time now is 11:37 PM.