Grounding Your Camper

Anything electric, AC or DC

Postby TD4FREEW/CTD » Wed Mar 29, 2006 8:36 pm

BILLYL wrote:Thank you - much clearer.

One final question - The neutral wires need to "FLOAT" I assume that I should insulate the bus from the box? Is a bus like that available - if not what type of insulating material should I use?

Thanks
Bill


your assumption is correct. the neutral bus should not be attached to the panel through any conductive parts.

usually, in a sub panel the neutral bus should already be "floating". only in a main panel, or meter panel will the neutral be bonded to the box.

of course, check to make sure.

if you have a multimeter, which i believe you should if you are undertaking an electrical project of this magnitude, you can use the continuity or Ohms feature of the meter to determine if the neutral is floating. simply put one test lead on the nuetral bus and the other to the panel chassis. you should get no reading.

hope this helps.
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Postby TD4FREEW/CTD » Thu Mar 30, 2006 2:26 am

Here is a typical sub panel installation:


on the left is the "bonded" ground bus. it is attached directly to the chassis via electrically conductive screws, thus it is bonded. in order to properly ground your trailer chassis you would need to either mount the bonded sub panel chassis directly to your trailer frame, or attach a ground wire from the bus to a grounding strap bonded to the trailer. keep in mind that paint can be an insulator and will hinder your conductivity when bonding your trailer.

on the right is the "Floating" Neutral bus. if you look closely at the picture, you can see that it is mounted to a piece of non conductive plastic and is in no way physically attached to the chassis of the sub panel, thus it is "floating" from the chassis

the large green wire on the ground bus goes to the ground/neutral bus in the main meter panel. on a trailer application it would go to the grounding prong on your power feed recepticle.

the large white wire would also go to the ground/neutral bus in the main meter panel on a household application. in the case of a trailer, it would go to the neutral prong on your power feed recepticle.



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Postby BILLYL » Thu Mar 30, 2006 6:21 am

As they say - A picture is worth a 1000 words. Now this is all making sense. No problem - I guess there was so much tech talk going on that not have a dictionary available of the various terms it was getting confusing............


Thanks

Bill
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Postby cracker39 » Thu Mar 30, 2006 8:01 am

TD4, I knew how the panels for my house were set up, like those in your picture with two busses, one for ground wires and one for neutral wires. That's why I was surprised that the little two-breaker box that I bought for my trailer main breaker has only a connection for the load to the breakers and one bus. They probably intend that you just tie the ground wires together with a wire nut, bonded to the box and trailer frame, and use the bus for neutral wires. Or, perhaps they didn't intend that this box would be used in a manner that would require the ground bonded to the box as it is not a "main" type breaker box. The package it came in is labeled "Circuit Breaker Load Center Indoor" and "Contents: QO Load Center and Cover". It's rated for 30 amps and is made by Square D.
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Postby TD4FREEW/CTD » Thu Mar 30, 2006 9:52 am

cracker39 wrote:TD4, I knew how the panels for my house were set up, like those in your picture with two busses, one for ground wires and one for neutral wires. That's why I was surprised that the little two-breaker box that I bought for my trailer main breaker has only a connection for the load to the breakers and one bus. They probably intend that you just tie the ground wires together with a wire nut, bonded to the box and trailer frame, and use the bus for neutral wires. Or, perhaps they didn't intend that this box would be used in a manner that would require the ground bonded to the box as it is not a "main" type breaker box. The package it came in is labeled "Circuit Breaker Load Center Indoor" and "Contents: QO Load Center and Cover". It's rated for 30 amps and is made by Square D.


Usually sub panels do not come with a ground bus. you have to buy them seperately.

that little panel should be just fine. go to home depot and ask one of their SUPER helpfull (sarcasm) employees to direct you to the ground busses. there are several different types so make sure you get the square D compatible bus for your panel.


another thing you could do for safety is use a GFCI breaker as your main breaker. this will ensure that your whole setup is GFI protected. everything after the breaker, at least.

this leads me to another question.....

what kind of service do campsites offer? is it only 120v, or do they have 240v setups as well?
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Postby cracker39 » Thu Mar 30, 2006 11:45 am

Thanks for the info. I already have GFCI outlets for my trailer. I don't really see the need to buy a bus for 3 wires as there will only be one breaker in the box. I'll drill through the side of the box and connect a wire to to my box and use it to connect to my incoming ground, the frame, and outgoing ground wire to the converter by twisting and soldering them together and covering with a wire nut.

I do want to get a 4-fuse block for my 12V sub panel, as the converter only has 3 12V fuses for appliances and I want to run two outlets and my lights on separate fuses. I can easily make a 12V ground buss with a piece of metal strap and small bolts and nuts.
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Postby TD4FREEW/CTD » Sat Apr 01, 2006 2:39 am

cracker39 wrote:Thanks for the info. I already have GFCI outlets for my trailer. I don't really see the need to buy a bus for 3 wires as there will only be one breaker in the box. I'll drill through the side of the box and connect a wire to to my box and use it to connect to my incoming ground, the frame, and outgoing ground wire to the converter by twisting and soldering them together and covering with a wire nut.

I do want to get a 4-fuse block for my 12V sub panel, as the converter only has 3 12V fuses for appliances and I want to run two outlets and my lights on separate fuses. I can easily make a 12V ground buss with a piece of metal strap and small bolts and nuts.


what did you plan on using to bond the ground to the box/trailer chassis? maybe an eyelet splice or somthin'? always helps to remove paint at the point of bonding as well.
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Postby cracker39 » Sat Apr 01, 2006 6:19 am

TD4FREEW/CTD wrote:what did you plan on using to bond the ground to the box/trailer chassis? maybe an eyelet splice or somthin'? always helps to remove paint at the point of bonding as well.


My shore cable is flexible, twisted wire. I have some solid 10ga 3+ground left over from installing a 220V outlet for the welder that I could use, but I think it may be too stiff to work with in tight places, so I may buy a length of 10ga flexible cable to run from the main breaker box to the converter. I will probably put a crimped "eyelet" on the end of the shore cable ground wire, the ground wire going to the converter, and one going to the chassis and connect all three eyelets to the box with one of the mounting screws, making sure I scrape the paint off the box where the screw contacts it to get a good connection.

The chassis ground wire will connect to one of the bolts holding the tongue box to the frame, again making sure I have scraped down to bare metal where the bolt connects to the frame.

I'll run a ground wire from my battery's negative post to the frame the same way as the 110VAC ground, using a tongue box to frame bolt on the battery side of the tongue box.


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