The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!


2017 NEC and Related
2017 NEC
Now Available!

Recent Posts
Parking lot pole light swap....
by gfretwell
10/24/16 08:46 PM
International Wire Colour Codes
by Tjia1981
10/23/16 12:08 PM
Son of Sparky
by HotLine1
10/20/16 07:43 PM
Speaking of Plugmold ...
by gfretwell
10/17/16 02:37 PM
Broken battery charger? Check for cobwebs!
by gfretwell
10/17/16 02:30 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 14
HotLine1 7
ghost307 7
renosteinke 6
Potseal 4
Who's Online
0 registered (), 292 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#8285 - 03/15/02 10:27 PM Why no neutral on 240
Looee Offline

Registered: 02/12/02
Posts: 13
Loc: Willmar, MN, 56201
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

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#8286 - 03/16/02 04:05 AM Re: Why no neutral on 240
sparky Offline

Registered: 10/18/00
Posts: 5545
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...

#8287 - 03/16/02 09:01 AM Re: Why no neutral on 240
Bob Offline

Registered: 02/05/02
Posts: 182
Loc: Mobile, AL, USA
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.

#8288 - 03/16/02 09:38 AM Re: Why no neutral on 240
Scott35 Offline

Broom Pusher and

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
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!

#8289 - 03/17/02 07:52 PM Re: Why no neutral on 240
Sandro Offline

Registered: 12/30/01
Posts: 449
Loc: Stoney Creek, ON, Canada

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).]


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals