Reply
 
Thread Tools Display Modes
 
Old 02-15-2017, 11:54 AM   #1
Mini-Skoolie
 
Join Date: Apr 2016
Location: New England
Posts: 68
Year: 2003
Coachwork: AmTrans
Chassis: International
Engine: T444E
Grounding House Electrical Question

Should I bond negative side of house battery bank to bus chassis? I am running 2 wires to all DC accessories from DC load center, so I wont be trying to use body or chassis for individual negative connections. Is it still necessary/recommended to bond negative battery connection to chassis for any reason? And if so, would the steel chair rail on the interior of the bus be adequate? My battery bank is inside the cabin so Id rather not have to go through floor to chassis if I dont have to. I would think the metal body would be adequate and is tied to chassis anyway?

My Aims inverter does say to bond safety ground to chassis as well. Can this be bonded to body instead? Is it bad to bond inverter ground and battery negative at same point or near each other?

Thanks for the help.
WhiteWhale is offline   Reply With Quote
Old 02-15-2017, 12:36 PM   #2
Bus Crazy
 
roach711's Avatar
 
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,557
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
If you'll be charging your house bank with the alternator you'll have to ground to the body/frame or run a negative cable back to the starting batteries. With no alternator charging and all house DC grounds hardwired back to the house bank you could forgo the chassis ground.

Many here have grounded to the metal body. The body & frame will be bonded together with a ground cable. Corroded connections can limit its effectiveness though, so it's a good idea to check and clean up any corroded ground cables/straps you find.

Your 120v AC service should be grounded to the bus also to avoid the dreaded "hot body" condition. Make sure your AC breaker box has separate neutral and ground bus bars and that the panel itself is grounded to the body/frame. The neutral and ground should only be combined back at the shore power panel.

To check your battery-to-frame-to-body ground connections set your voltmeter to 200 OHMS (not 200K ohms) Touch the leads together to check that the meter is working properly (should read 0 ohms) then put one lead on the battery ground post and one on a clean (paint/rust free) spot on the body. You should see zero ohms with a good ground. Anything over .5 ohms and you should check your connections.
__________________
The Roach Motel
roach711 is offline   Reply With Quote
Old 02-15-2017, 01:05 PM   #3
Bus Nut
 
Join Date: Feb 2014
Location: Cuyahoga Falls Ohio
Posts: 362
Year: 1997
Chassis: Ford e-350 single wheel
Engine: 5.4 litre
Rated Cap: 12
Roach, I like the way you explain things, simple and to the point. I'm an electrician but can't find the words like you can. Thanks for all you do.
Quote:
Originally Posted by roach711 View Post
If you'll be charging your house bank with the alternator you'll have to ground to the body/frame or run a negative cable back to the starting batteries. With no alternator charging and all house DC grounds hardwired back to the house bank you could forgo the chassis ground.

Many here have grounded to the metal body. The body & frame will be bonded together with a ground cable. Corroded connections can limit its effectiveness though, so it's a good idea to check and clean up any corroded ground cables/straps you find.

Your 120v AC service should be grounded to the bus also to avoid the dreaded "hot body" condition. Make sure your AC breaker box has separate neutral and ground bus bars and that the panel itself is grounded to the body/frame. The neutral and ground should only be combined back at the shore power panel.

To check your battery-to-frame-to-body ground connections set your voltmeter to 200 OHMS (not 200K ohms) Touch the leads together to check that the meter is working properly (should read 0 ohms) then put one lead on the battery ground post and one on a clean (paint/rust free) spot on the body. You should see zero ohms with a good ground. Anything over .5 ohms and you should check your connections.
leadsled01 is offline   Reply With Quote
Old 02-15-2017, 01:26 PM   #4
Mini-Skoolie
 
Join Date: Apr 2016
Location: New England
Posts: 68
Year: 2003
Coachwork: AmTrans
Chassis: International
Engine: T444E
Quote:
Originally Posted by roach711 View Post
If you'll be charging your house bank with the alternator you'll have to ground to the body/frame or run a negative cable back to the starting batteries. With no alternator charging and all house DC grounds hardwired back to the house bank you could forgo the chassis ground.

Many here have grounded to the metal body. The body & frame will be bonded together with a ground cable. Corroded connections can limit its effectiveness though, so it's a good idea to check and clean up any corroded ground cables/straps you find.

Your 120v AC service should be grounded to the bus also to avoid the dreaded "hot body" condition. Make sure your AC breaker box has separate neutral and ground bus bars and that the panel itself is grounded to the body/frame. The neutral and ground should only be combined back at the shore power panel.

To check your battery-to-frame-to-body ground connections set your voltmeter to 200 OHMS (not 200K ohms) Touch the leads together to check that the meter is working properly (should read 0 ohms) then put one lead on the battery ground post and one on a clean (paint/rust free) spot on the body. You should see zero ohms with a good ground. Anything over .5 ohms and you should check your connections.


Thanks! I won't be charging house bank from alternator so it sounds like no need to ground batteries then.

As for AC my inverter/charger is equipped with a relay that uses the chassis ground from the inverter when running off batteries, but switches to shore power ground only when plugged in. I was under the impression that the relayed ground from the inverter is the only place I should bond to chassis. This will serve as ground when inverting, and the shore ground should be the only ground when plugged in. If I were to bond AC panel to chassis as well wouldn't that create two separate grounds when plugged into shore power?


Sent from my iPhone using Tapatalk
WhiteWhale is offline   Reply With Quote
Old 02-15-2017, 02:00 PM   #5
Bus Crazy
 
roach711's Avatar
 
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,557
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
I've never installed an inverter/charger so I'd go with the manufacturer's instructions. That said, I can't imagine how multiple AC grounds would be a problem. The relay may be there to switch between a utility ground and a generator ground. When in doubt a quick call to the manufacturer's tech support should be the final word. In this case, do not rely on my advise.

Remember that an AC ground is a safety circuit only and doesn't normally carry any current. A DC ground is the return circuit. A DC ground has the same purpose as an AC neutral.
__________________
The Roach Motel
roach711 is offline   Reply With Quote
Old 02-15-2017, 02:11 PM   #6
Bus Crazy
 
roach711's Avatar
 
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,557
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
Leadsled - You're like my nephew who's also an electrician. He knows the subject instinctively but when he tries to explain in mugglespeak it's hard for him. It's like explaining how to walk, he doesn't have to think about it anymore so the words are irrelevant.

I have to rethink (sometimes relearn) the subject each time I post so I have to make it understandable to myself first.
__________________
The Roach Motel
roach711 is offline   Reply With Quote
Old 02-15-2017, 02:44 PM   #7
Bus Crazy
 
roach711's Avatar
 
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,557
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
I had a look at an AIMS inverter/charger manual and you may be thinking about the automatic neutral to ground switching feature. When plugged in, the shore power main panel AC ground and the inverter AC ground are connected as they normally would be. At the main panel (and only at the main panel) the neutral and ground are connected together. This makes the breakers work properly. Don't ask me why.

When on inverter power there is no "main panel" so the relay connects the AC ground and neutral at the inverter so the breakers will work as they should. This, in effect makes the inverter the main power panel.

It's best to think of all this as magic.

At any rate, there is a ground lug on the inverter case that should be cabled to a good body ground.
__________________
The Roach Motel
roach711 is offline   Reply With Quote
Old 02-15-2017, 03:34 PM   #8
Mini-Skoolie
 
Join Date: Apr 2016
Location: New England
Posts: 68
Year: 2003
Coachwork: AmTrans
Chassis: International
Engine: T444E
Quote:
Originally Posted by roach711 View Post
I had a look at an AIMS inverter/charger manual and you may be thinking about the automatic neutral to ground switching feature. When plugged in, the shore power main panel AC ground and the inverter AC ground are connected as they normally would be. At the main panel (and only at the main panel) the neutral and ground are connected together. This makes the breakers work properly. Don't ask me why.

When on inverter power there is no "main panel" so the relay connects the AC ground and neutral at the inverter so the breakers will work as they should. This, in effect makes the inverter the main power panel.

It's best to think of all this as magic.

At any rate, there is a ground lug on the inverter case that should be cabled to a good body ground.


Roger that. So the inverter ground lug to body only. No need to bond my breaker panel to body as well?


Sent from my iPhone using Tapatalk
WhiteWhale is offline   Reply With Quote
Old 02-15-2017, 03:58 PM   #9
Bus Crazy
 
roach711's Avatar
 
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,557
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
The sub panel would ground back to the inverter so a ground from the panel to body wouldn't be necessary.

Wrapping my head around the AC and DC wiring in our bus was easily the hardest part of our conversion.
__________________
The Roach Motel
roach711 is offline   Reply With Quote
Old 02-15-2017, 04:10 PM   #10
Almost There
 
Join Date: Jan 2016
Location: Tepme AZ
Posts: 96
Year: 1976
Coachwork: Crown
Engine: Detroit Diesel 6-71
Rated Cap: 52 pax
Quote:
Originally Posted by roach711 View Post
Wrapping my head around the AC and DC wiring in our bus was easily the hardest part of our conversion.
I hear that. That's what I'm working on right now
__________________
-Chevy
Chevydude01 is offline   Reply With Quote
Reply

Thread Tools
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

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 08:57 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.