Go Back   iRV2 Forums > MOTORHOME FORUMS > MH-General Discussions & Problems
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 04-18-2010, 01:02 PM   #1
Senior Member
Join Date: May 2003
Posts: 291
Electric dryer

If i am connected to 15A or 30A shore power the dryer outlet shows 120VAC on the hot legs (ie +120VAC on red and +120VAC on black w.r.t neutral and w.r.t ground). The voltage difference between the red and black is zero. Will a 240VAC electric dryer work in this situation if accidentally turned on ( i don't want it to)?

On 50A shore power or generator power, i am fine as the voltage difference between red and black is 240VAC (ie (120VAC) - (-120VAC))

caymann is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 04-19-2010, 02:40 AM   #2
Community Moderator
RV Wizard's Avatar

Country Coach Owners Club
Appalachian Campers
Gulf Streamers Club
Join Date: Mar 2000
Location: Chattanooga, Tn.
Posts: 12,062
The motor of the dryer will run (it is 120vac) but the heating element will not come on. Your generator must also be something like a 12 k; not the 7.5 or 8 k quiet diesels as they do not put out 240 vac.

Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7
RV Wizard is offline   Reply With Quote
Old 04-19-2010, 05:59 AM   #3
Senior Member
Join Date: May 2003
Posts: 291
That is good to know that heating element will not come on, since it sees 0V instead of 240VAC , right?
In the generator mode (10kW onan, outputs +120VAC and -120VAC in each hot leg), i am not worried. Neither is it a problem in 50A, 240VAC shore power mode.
Only when shore power is 30A, 120VAC and 15A,120VAC i don't want the heating elements to energize or damage anything in the dryer. In these modes i see 120VAC in each leg of the dryer power outlet.
caymann is offline   Reply With Quote
Old 04-19-2010, 01:13 PM   #4
Senior Member
PlayItForwrd's Avatar
Tiffin Owners Club
Join Date: Feb 2010
Posts: 315
correct me if I'm wrong (probably am ) but isn't your "minus 120vac actually a PLUS 120vac, but 180 out of phase with the other leg?
2000 40' Tiffin Allegro Bus \ 2003 Chaparral 260 SSI
1988 53 x 14 Skipperliner \ 1995 32' Party Cruiser
1984 Goldwing Aspencade \ 1976 Harley Sportster
PlayItForwrd is offline   Reply With Quote
Old 04-19-2010, 02:38 PM   #5
Senior Member
Join Date: May 2003
Posts: 291
yes, you are right. it is a vector.
-120VAC = 120VAC (magnitude) and 180deg (phase)
+120VAC = 120VAC (magnitude) and 0/360 deg (phase)
caymann is offline   Reply With Quote
Old 04-20-2010, 07:01 AM   #6
Moderator Emeritus
Gary RVRoamer's Avatar

Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,635
The plus and minus actually indicates the phase difference in a 240v alternating current circuit. One leg is in the "negative" phase whenever the other in in the "positive" phase. Mathematically, the plus and minus signs make the calculation work, i.e. the voltage difference between them is 240v ( +120 and -120). Clear as mud, right?

It is merely convenient to think about the legs as plus and minus, as if it were two DC circuits. We use a similar mathematical convenience in DC circuits when we talk about plus and minus. The plus and minus actually represent direction of current flow rather than the physical charge present, but the arithmetic works and it makes it easier to comprehend the effects. And it all gives electrical engineers and physicists something to argue about over cocktails!

Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Haldex Air Dryer Rebuild quikduk Spartan Motorhome Chassis Forum 6 09-03-2011 04:14 AM
Heat Pump - No Electric Heat Drifterpilot MH-General Discussions & Problems 3 04-11-2009 07:13 PM
DOE Announces $30 Million for Plug-in Hybrid Electric Vehicle Projects Hitchhiker Going Green 2 06-22-2008 02:24 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 06:19 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.