Ground Versus "Dedicated Ground"

DesertGuy · Post by **DesertGuy** » Tue Apr 10, 2007 4:17 pm

Been doing a little reading and noticed some components state they they need to have a ground, while others state they need a "dedicated ground".

Considering that a car is grounded from the negative battery terminal to the chassis, engine to the chassis, and engine to the body, what is the difference in having a component grounded in series with other components and having its own grounding wire? Seems that everything is working its way back to the car structure in one form or another.

Skidmark · Post by **Skidmark** » Tue Apr 10, 2007 4:57 pm

The ECU for my Suby (a Stinger, made by EMS) has a ground wire that lists "must be connected to the negative terminal of the battery - do not attach to chassis ground". I assumed this was to prevent interference from other electrical devices connected to the chassis ground. Other than that, not sure...

Ol'fogasaurus · Post by **Ol'fogasaurus** » Tue Apr 10, 2007 6:42 pm

I ground to the engine/transaxle first then to the chassis. I want the best ground I can for the engine.

If you are using a VW pan stock, or shortened pan, you are using old metal. I do not trust anyone else's work, welding, or what have you so I run a ground wire to the area needed (bussed stripor post) and use it. this is especaill true when working around fiberglass.

I was once told that the ground wire should be the same size as the load wire. While this is not true all the time, but it is something to be considered.

For what it is worth. Lee

DesertGuy · Post by **DesertGuy** » Tue Apr 10, 2007 6:59 pm

Ol'fogasaurus wrote:I was once told that the ground wire should be the same size as the load wire. While this is not true all the time, but it is something to be considered.

As a side topic... Alot of battery cables are either 4 AWG or 6 AWG. However, many "audio" folks swear by 1 AWG. I understand that the larger the wire (cable), the less resistance and therefore, a better path. Is there an appreciable difference in using 1 AWG for both the load and ground in a car?

Ol'fogasaurus · Post by **Ol'fogasaurus** » Tue Apr 10, 2007 10:03 pm

I try to use "0" leads, if I can find them. I have heard of buys using "000" which I think are arc welding leads. Over kill, maybe but you are sure to get the best out of your battery this way.

Post by **2088 bob** » Wed Apr 11, 2007 2:13 am

lee gave some very good advice there ground lead should be at same size as your power lead

MNAirHead · Post by **MNAirHead** » Wed Apr 11, 2007 5:45 am

I've always been coached that when running a custom loom... to run directly from the battery with a big fat wire to a terminal bar.. ground everything to the terminal bar

Is this overkill

Post by **2088 bob** » Wed Apr 11, 2007 2:21 pm

tim brings up a very good point

which now brings me to a subject i have been wanting to cover for quite some time especially with you guys building fiberglass buggies please direct your attention to the following picture

If you look very carefully at the bottom center of the pic you will see a really fat black wire going to a short little terminal strip

That is the ground buss ,the heavy wire feeding it is a 8ga wire good for 40 amps that wire goes right back to the negative post of the battery The wire feeding the power panel is also 8ga so now we have set
up the what goes in must come out scenario

every item that requires ground is hooked to that terminal strip which now assures a solid ground path back to the battery

this is the best way to handle grds in a glass car

DesertGuy · Post by **DesertGuy** » Wed Apr 11, 2007 3:16 pm

Bob, considering that all circuits are grounded to this bar... what accounts for the size difference between the grounding bar and the size of the terminal block going out to the car's components?

Also, do you have a "large" version of this pic that can be emailed/pm'd for learnin' purposes? Thanks.

Post by **2088 bob** » Wed Apr 11, 2007 3:37 pm

i think i under stand your question steve lets use these 2 examples if i have 11 relays in a row i jump from one relay to the next with my ground then come off the last relay with one ground wire to the ground bus or if i have 15 gauges in a row i jump from one gauge to the next hit all 15 and bring one tail back to the ground bus so now i have effectively grounded 26 devices with just 2 connections to the ground bus does this make sense steve

lets see if i can find the cd rom with these pics and then make it big

DesertGuy · Post by **DesertGuy** » Wed Apr 11, 2007 5:06 pm

2088 bob wrote:i think i under stand your question steve lets use these 2 examples if i have 11 relays in a row i jump from one relay to the next with my ground then come off the last relay with one ground wire to the ground bus or if i have 15 gauges in a row i jump from one gauge to the next hit all 15 and bring one tail back to the ground bus so now i have effectively grounded 26 devices with just 2 connections to the ground bus does this make sense steve

...That makes perfect sense, thanks