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.
Reply
  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 12-07-2012, 07:34 PM   #1
Member
 
Join Date: Jan 2012
Posts: 66
30 amp line for my M.H.

Hi don't really know how to post but here goes. I want to put in175ft. of 8/3wire underground,from my house panel to a 30 amp post hook-up I read where 8/3 is rated as 55amps. I know that I will lose some in 175 ft.my question is will i still have 30 amps or better, can some tell me. There won't be anything else on that line and I will come off a 40 amp breaker. Hope some one can hel me.
thanks.

dsilva
__________________

__________________
dsilva 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 12-07-2012, 07:38 PM   #2
Senior Member
 
rsha's Avatar
 
Join Date: May 2012
Location: Palacios, Tx
Posts: 173
It's not amps you need to worry about. Voltage drop will be you problem. 8/3 seems like a little small for that distant. Might want to check the code.
__________________

__________________
40' HR Navigator
rsha is offline   Reply With Quote
Old 12-07-2012, 07:49 PM   #3
Senior Member
 
Pusherman's Avatar
 
Join Date: Oct 2006
Location: Rochester NY
Posts: 2,545
Good plan to use the larger wire to prevent the voltage drop. But it should still be 'fused' at 30A for the breaker size, not 40A.

Note: If your motorhome has a 30A 3 wire service, then technically you need 2 conductors with ground. In other words, 10/2 with ground, or in your case of running the longer length, 8/2 with ground. If you have a 50A service, then it's a different story. You need 3 conductors with ground, as technically it's a 240V service. Amperage will determine the size of the wire.

Going up one size for your distance is a good idea.
__________________
Don
'07 Winnebago Journey 34H - CAT C7, Koni's, MCU's, SS Bell Crank, Safe-T-Plus
'07 HHR Toad, SMI AFO, Blue OX
Pusherman is offline   Reply With Quote
Old 12-07-2012, 08:02 PM   #4
Senior Member
 
WeatherTodd's Avatar
 
Monaco Owners Club
Workhorse Chassis Owner
Join Date: Nov 2009
Location: FL
Posts: 1,147
Voltage Drop Calculator
__________________
WeatherTodd is offline   Reply With Quote
Old 12-07-2012, 08:10 PM   #5
Senior Member
 
Workshop's Avatar
 
Join Date: Sep 2007
Posts: 1,334
Here is another Voltage Drop Calculator. Looks like you will need at least a #6 for that length. As stated above connect with a 30 amp breaker.
__________________
2000 Alpenlite, 29 ft Valhalla - 2014 F350
Workshop is offline   Reply With Quote
Old 12-07-2012, 08:15 PM   #6
Member
 
Join Date: Jan 2012
Posts: 66
30amp line

Quote:
Originally Posted by Pusherman View Post
Good plan to use the larger wire to prevent the voltage drop. But it should still be 'fused' at 30A for the breaker size, not 40A.

Note: If your motorhome has a 30A 3 wire service, then technically you need 2 conductors with ground. In other words, 10/2 with ground, or in your case of running the longer length, 8/2 with ground. If you have a 50A service, then it's a different story. You need 3 conductors with ground, as technically it's a 240V service. Amperage will determine the size of the wire.

Going up one size for your distance is a good idea.
are u guys saying I need 10/3 wire. i will be hooking up to a 30 amp cord
from the post to the M.H. no washer dryer. I know I can't run 2 A.C. on 30 amps.I will use it to charge the battries while its parked in the barn and not have to turn off the fridge. Thanks for ur replies Pusherman and rsha
__________________
dsilva is offline   Reply With Quote
Old 12-07-2012, 08:22 PM   #7
Senior Member
 
jfran304's Avatar
 
Tiffin Owners Club
Workhorse Chassis Owner
Join Date: Oct 2009
Location: Warner Robins, GA
Posts: 2,488
Why don't you install a 50 Amp hookup instead of the 30 Amp? It will cost you a little more but then you will be able to run everything in the coach.

Jon
__________________
Jon & Sue Francis (Retired U.S.A.F.)
Lil Girl-Rescued, Abby Rescued, Peaches Rescued
06 Allegro 35TSA Workhorse Chassis
2013 Chevy Spark Dinghy
jfran304 is offline   Reply With Quote
Old 12-07-2012, 09:00 PM   #8
PEJ
Junior Member
 
PEJ's Avatar
 
Join Date: Jul 2012
Posts: 24
#6 is still not enough at 30 amps, but more importantly you need a licenced electrician.
__________________
Peter J, New Brunswick, Canada
2001 Palomino Pony 21
MEC Tarn2 (6 lb) - Backpacking, Canoeing
PEJ is offline   Reply With Quote
Old 12-07-2012, 09:17 PM   #9
Senior Member
 
vsheetz's Avatar


 
Fleetwood Owners Club
Ford Super Duty Owner
Join Date: Jun 2012
Location: SoCal
Posts: 11,789
I would run three wires and a ground - leaving the 4th wire unused or configured as a MWBC (multi wire branch circuit = provides for two 120v circuits) for now - and allowing for converting to 50 amp service in the future. Three #6 current carrying (white/black/red) plus one #10 ground (green), all THHN assuming in conduit.

How is this going to get there? If trenching should be 18" deep in conduit to meet code in most places. If only 120v circuit can be 12" deep. Direct bury is 6" deeper. Conduit is highly recommended -easier/cheaper to dig, can pull to change or add wires in the future. Direct bury cable is cheaper. Trenching is easy to do - hire a couple day workers to do it, give them a 4" trenching shovel and a digging bar.

Whether you need a licensed electrician depends on your local requierments. Here in SoCal I can pull a owner builder permit and do it all myself. If you do need or want a electrician to do it - do the trenching and wire running yourself, then have the electrician just do the hook-ups at either end.
__________________
Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.
vsheetz is offline   Reply With Quote
Old 12-07-2012, 10:20 PM   #10
Senior Member
 
Join Date: Jan 2012
Location: seattle, wa.
Posts: 413
Send a message via Skype™ to LandKinaMoho
Can you say CODE. Trench inspection, conduit , backfill etc Permit. Just sayin.
__________________
1999 National Dolphin
1995 Range Rover County SWB.
Sailor, Dickens, Zooki, Koko.
LandKinaMoho is offline   Reply With Quote
Old 12-07-2012, 10:52 PM   #11
Senior Member
 
bluepill's Avatar
 
Join Date: Jan 2011
Location: Pensacola, FL
Posts: 2,246
dsilva: If you are only charging batteries and running an LP/Electric fridge, you will probably only be using about 15 amps, not the full 30. This assumes that you can limit your charger/converter to 10 amps input (many have this ability to adjust) and your fridge draws 4 amps. With the charger and fridge off, you would use about 14 amps on a single A/C unit rated at 13,500 BTU.

I have used a 15 amp circuit to power my MH as described above, and it has worked fine.

Calculation below:

1 conductors per phase utilizing a #8 Copper conductor will limit the voltage drop to 3.03% or less when supplying 15.0 amps for 175 feet on a 120 volt system.
For Engineering Information Only:
40.0 Amps Rated ampacity of selected conductor
0.7421 Ohms Resistance (Ohms per 1000 feet)
0.052 Ohms Reactance (Ohms per 1000 feet)
4.8 volts maximum allowable voltage drop at 4%
3.625. Actual voltage drop loss at 3.03% for the circuit
0.9 Power Factor
__________________
2008 Itasca Meridian 37H & 2015 Flagstaff T12RBST
2011 & 2012 Len & Pat's "One lap of America"
27K miles & 41 states in 13 months - Woo Woo
Yellowstone Lake 6-1-2012
bluepill is offline   Reply With Quote
Old 12-07-2012, 10:56 PM   #12
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 14,970
Quote:
Originally Posted by LandKinaMoho View Post
Can you say CODE. Trench inspection, conduit , backfill etc Permit. Just sayin.
X2. If anything goes wrong, remember " Murphy , and his law " the first thing any insurance company is going to look for is a permit, the second is a way not to pay a claim.
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 12-07-2012, 11:47 PM   #13
Senior Member
 
vsheetz's Avatar


 
Fleetwood Owners Club
Ford Super Duty Owner
Join Date: Jun 2012
Location: SoCal
Posts: 11,789
Agree - having things such as this properly permitted and inspected is a must.

Here is a great resource forum for home improvment activities. I have done a whole house renovation, detached 24x30 workshop, and several other projects with excellent advice from the good folks here. All with owner builder permiting and inspections. DIY Chatroom - DIY Home Improvement Forum
__________________

__________________
Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.
vsheetz is offline   Reply With Quote
Reply



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


» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:11 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.