ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Pool Lights?
by Papa - 09/18/20 05:26 PM
Ever been afflicted by Gout?
by mbhydro - 09/15/20 05:50 PM
Questioning the electrical norms
by gfretwell - 09/13/20 01:17 PM
120/208 gives 240? please clarify
by NORCAL - 09/13/20 01:08 AM
Lock-down Thread
by Trumpy - 09/11/20 11:17 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 17 guests, and 13 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Why no neutral on 240 #8285 03/16/02 02:27 AM
Joined: Feb 2002
Posts: 11
L
Looee Offline OP
Member
I'm an electrician student so I'm kind of new to this. Why is it that 240V circuits don't use a neutral? I have asked my teacher but I'm not sure he understood what I was asking, and nobody else in my class seems to know either.

Work Gear for Electricians and the Trades
Re: Why no neutral on 240 #8286 03/16/02 08:05 AM
Joined: Oct 2000
Posts: 5,389
S
sparky Offline
Member
A good Q.
This has had much past attention in this forum, especially via Scott who moderates the theory section.
Consider that some countries have no nuetral in thier grid, and the maladies it causes us in ours... [Linked Image]

Re: Why no neutral on 240 #8287 03/16/02 01:01 PM
Joined: Feb 2002
Posts: 182
B
Bob Offline
Member
Looee
Some 240 volt circuits do require a neutral.
A dryer circuit requires a neutral because besides the motor there are components that
require 120 volts. Therefore the neutral serves a the return conductor for these components. If a device such as a 240 volt welder is used, the power is conducted over the 2 energized conductors. There is no need for the neutral. A grounding conductor would be needed to ground the welder frame.

Re: Why no neutral on 240 #8288 03/16/02 01:38 PM
Joined: Oct 2000
Posts: 2,721
Scott35 Offline
Broom Pusher and
Member
A quick and dirty answer is:

The "Neutral" [Better known as the Grounded Circuit Conductor] is no different than any other circuit conductor - only it is usually Grounded.

On a simple 1 phase 3 wire system, the "Neutral" is derived from a "Center Tap" on the secondary winding.
This center tap effectively cuts the winding's normal output voltage of 240 VAC by half, so from each "End" of the secondary winding to the Center Tap, the Voltage is 120 VAC.

It does not need to be Grounded for this to function properly - nor any other "Common Grounded Circuit Conductor".

If you have further questions, I would suggest starting a thread in the Theory area.

Also take a look at some of the Transformer schematics in the Technical Reference area, as they will help explain things better.

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Re: Why no neutral on 240 #8289 03/17/02 11:52 PM
Joined: Dec 2001
Posts: 444
S
Sandro Offline
Member
Looee....

Some 240V circuits, like a motor, baseboard heater, AC compressors, welders, etc. carry a balanced load (basically, each conductor carries equal amounts of current). So therefore, a neutral is not required to return the unbalanced current. As mentioned elsewhere, some 240V circuits, like a stove or dryer use current other then for the heating element or require 120V at the appliance, so the load is not always balanced, and thus a neutral is required to carry the unbalanced load.

[This message has been edited by Sandro (edited 03-17-2002).]


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
JoeKP
JoeKP
Berkley, MA
Posts: 144
Joined: March 2008
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 8
NORCAL 3
Popular Topics(Views)
269,922 Are you busy
204,353 Re: Forum
192,572 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3