Grounding questions...frame vs grounding bar...

[kayakrguy]

Hi folks,

Many moons ago I posted a topic about mounting a license plate light.
One central conclusion by members was that the BEST WAY TO GROUND was to have separate grounding wires from each load to a grounding bar.

Here are my questions...

1)Since, for example, my tailights and amber running lights have 'internal grounds' e.g. they are designed to be grounded to the frame via the screw that holds them to the frame, I assume grounding these to a 'grounding bar' would involve running a wire from the mounting screw to the bar??

2) The grounding bar--where do you get same? Do you attach it to the frame? And, I assume you run a wire from the bar to the grounding wire to the car? If not, I don't get the point of using a grounding bar attached to the trailer frame with no connection to the car ground--how is that different from grounding to the frame alone?

Light in these dark corners would be appreciated.

Thanks,

Jim

[PaulC]

Hi Jim, with all my trailers (I have 3) I only use the ground back to the vehicle. I have found that relying on the frame eventually causes all sorts of weird things to happen. By using the vehicle as the earth you only have one spot to take care of if anything strange happens. It also helps to keep the circuits(tail lights and internal trailer power) separated and lessen the probability of crossed circuits.
Cheers
Paul

[Miriam C.]

Well here we go. I have mine grounded to the vehicle but that didn't work too well so I did both. They work now.

[Mike C.]

Quote kayakrguy:

2) The grounding bar--where do you get same? Do you
attach it to the frame?



I work for a wholesale electrical distributor and we sell them every day.
The ones we sell come in a 5,10,14,& 20 hole configurations.
I've also seen them at Lowe's and Home Depot.

Yes, you would bolt it to the frame.

[Podunkfla]

This may be redundant information? But, I think the main reason not to rely on just grounding just to the trailer frame is that you connection to the tow vehicle is then through the hitch? Which is often not in good contact what with grease on the ball and going over bumps and stuff. Just my thoughts. Tell me if I'm off base here?

[madjack]

....in my experience, corrosion and rust between the frame material(steel) and the wire(copper or AL crimp on terminals) is the biggest culprit and best reason for going with a ground block or a direct connection(bringing all grounds together and soldering)....a ground block can be had from the electrical dept of any box, hardware or electronics supply(RadioShack) house...they can be mounted anywhere covienient...be it wooden body or steel frame(steel frame would be preferred location) and the white wire on a standard wiring harness would be connected to it, along with your grounds..........
madjack

[Alphacarina]

Jack is right on (as usual) . . . . except that what he thinks are aluminum crimp rings are actually tinned copper - You can (and should) solder the wire to the connection after you crimp it and you can't solder aluminum. Aluminum has no place in any electrical scheme because it's the most corrosive common metal we have. Aluminum house wiring was legal for a time in the '50's and it's burned down more houses than you could ever count

When you build something and ground everything to the frame, it will work perfectly (so long as you're not depending on the hitch to 'ground' it to the car) and you've saved several feet of wire

BUT - You've put many connections in places where corrosion will begin to work on them. Dissimilar metals (both the steel of the frame, but also the copper inside the tinned crimp ends) are out in the weather, attracting moisture and that will eventually cause enough corrosion to compromise the electrical integrity of many of the connections

I've wired boats for 25 years or so and have some hard and fast rules which could carry over here

1.) Solder all crimp fittings
2.) Run seperate return (ground) wires to a central grounding block - Preferably near the positive block which distrubutes battery power
3.) Do not use steel screws for electrical connetions. Brass or chrome plated brass are best . . . . stainless is second best
4.) Try not to have any connections in a damp area, or any area where they can get wet
5.) Try not to have any splices in the wires - If you MUST have a splice, don't use a crimp splice - They are WORTHLESS and collect moisture like a sponge. Crimping and soldering a pair of eyes on the two wires connectd by a brass nut and bolt is much better. Heat shrink over the completed connetion. Household twist connections are ILLEGAL on boats . . . . they collect water like sponges too and funnel it down into the strands of wire, where corosion is rampant

You tear WILL work with everything grounded to the frame, and if it seldom gets wet, it will work OK for a long time, but when corrosion begins to make things 'erratic' the troubleshooting and repair can be difficult and time consuming

Don

[Dale M.]

One thing everybody seem to miss in wiring is have a clean "bright" metal surface to connect to and use a anticorrosive grease on connection. I even use it in crimp connections....

Anticorrosive grease prevents oxygen from entering connection, without oxygen, corrosion is cut to almost nil...

You can find small tubes of a silicone grease often called "light bulb grease" in local hardware stores.... And yes it helps to use it in light bulb socket to prevent corrosion in actual connection in socket, and will also prevent bulb from gluing itself into socket by corrosion...

Dale

[angib]

My vote is for:
- Separate earth (sorry, 'ground') conductor everywhere - never use any trailer part, ever.
- No (repeat no) joints in any cable except inside fittings that remain accessible.
- Never assume anything is watertight - and that includes 'watertight' fittings and junction boxes.

I've found that as a corrosion preventer there's a lot to be said for automotive aerosol 'cavity wax' - the stuff intended to be sprayed inside vehicle box sections, if the same stuff's sold in Merka as here. Sprayed over wiring and the backs of fittings, it keeps quite a lot of damp out without seeming to lock any damp in - which is a typical failing of many other products.

Andrew

[kayakrguy]

I wanna thank everyone for the information and suggestions. Once again, I am struck by regional/local differences in retail big box and hardware stores. This is not the first time I have mentioned this, but this is another example...folks from South/Midwest say grounding bars are easy to get at retail in big box, hardware etc.... Well Lowes and HD nearboy have grounding RODS, but not bars.

Will try Rad shack tomorrow....

Re electrolysis--will hasten corrosion in almost any metal-metal contact between unlike metals....undercarriages of trailers also get lots of salt...ditto hastens corrosion...which is why our highway system is headed for the toilet....AVOID BRIDGES, especially in the North...salt has dissolved rebar and lots of critical structural elements...

Jim

[Dale M.]

Get a safety ground strip that goes inside AC breaker panel.... It has many holes you can insert wires into and then tighten screws into wire...

They are common in any hardware store pr home improvement center in electrical supply dept. near breaker panels and other electrical components...

http://electrical.hardwarestore.com/14- ... 13841.aspx

I know... People will whine, its not shiny copper... But its good enough to go into your breaker panel to protect your home or office, it is good enough to go into your TD...

Dale

[madjack]

Jack is right on (as usual) . . . . except that what he thinks are aluminum crimp rings are actually tinned copper - You can (and should) solder the wire to the connection after you crimp it and you can't solder aluminum. Aluminum has no place in any electrical scheme because it's the most corrosive common metal we have. Aluminum house wiring was legal for a time in the '50's and it's burned down more houses than you could ever count

Don...I knew that...D'OH...I just wasn't wide awake when I posted...that is why I rely on you and Dale to keep me on the straight and narrow path of electrical enlightenment ...I also solder virtually everything I can.....
madjack

[kayakrguy]

I have question about how grounding the trailer works...

Several times the point was raised that grounding to the frame is not ideal because, among other things, when the hitch bounces (separates breiftly from the ball) you lose ground, trailer lights flicker...

I thought the ground to the car frame was maintained throught the ground wire from the car to the trailer wire harness and then to the trailer frame.

To wit: The wire doesn't stop acting as a ground when the hitch bounces.

That reinforces in my mind what everyone is suggesting about the ground bar...it connects up with the ground wire from the car....making a stronger ground, less likely to be compromised by corrosion etc???

Just wanna be sure I understand the mechanical nature of this set up...

Thanks,

Jim

[bobhenry]

If you look at most trailer wiring harnesses there is 20' of brown green and yellow but about 5' of white. They are assuming you will ground the white wire " THE CAR GROUND " to the trailer frame. All we are saying is continue the white wire to a grounding bar and run a dedicated ground to each and every 12 v dc fixture and light and things won't flicker. You are connecting each and every 12 v dc connection essentially to the tow vehicles battery ground.

[Alphacarina]

The highest quality DC electrical components are from Blue Sea Systems and you can buy them at most marine stores

Beware however that anything along this line you buy from West Marine can usually be bought somewhere else for less than half the West Marine price - They don't 'make boating more fun' . . . . they 'make boating more EXPENSIVE'

eBay is a good source if you don't have a local store - Do an eBay search for 'Blue Sea System' and check it each day and you'll be surprised at what you can find and what it will cost you. I frequently buy things that West Marine would sell for $100 there for $35 or $40

Here's a current listing for a terminal block which can be used for either grounding wires or for 12 volt distribution

http://cgi.ebay.com/BLUE-SEA-SYSTEMS-MINIBUS-100-AMPERE-COMMON-BUS_W0QQitemZ250133675935QQihZ015QQcategoryZ310QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

The shipping is kinda high, but if you found one of these in a West Marine store, it would probably be $25

Don