Should 12V stay grounded to the Frame?

[SaltCreek]

Just got my trailer, and want to install lights first so I can see when I am working on it. Should the 12V stay grounded to the frame if I plan on running both 12V and 120V? I know the current interior lights installed by the manufacturer are grounded to the frame. I tried to search but did know what to search for.

Thanks

[Padilen]

I'm working on my electric now also. I've read until my eyes bled. What I've found is more questions than answers. But I'm going with grounding both AC and DC (battery) to my aluminum frame CTC.

[Gerdo]

12 volt DC, negative all goes to the metal frame. Mainly because it's there and you don't have to run another wire. The positives get fused and switched.

120 volt AC, three wire (positive, negative and ground) all go to the load. The positive gets fused and switched. The main ground must go the the trailer's metal frame.

[Padilen]

Gerdo
Thanks.

[MtnDon]

12 volt DC, negative all goes to the metal frame. Mainly because it's there and you don't have to run another wire. The positives get fused and switched.

.

This pops up every so often in a topic. Eventually relying on the frame for the negative conductor often results in more trouble and time expended in troubleshooting than the value of any wire saved. Running a negative DC wire to each light and device ensures a good complete circuit and makes for easier troubleshooting if problems develop.

[aggie79]

12 volt DC, negative all goes to the metal frame. Mainly because it's there and you don't have to run another wire. The positives get fused and switched.

.

This pops up every so often in a topic. Eventually relying on the frame for the negative conductor often results in more trouble and time expended in troubleshooting than the value of any wire saved. Running a negative DC wire to each light and device ensures a good complete circuit and makes for easier troubleshooting if problems develop.

+1

[angib]

Yes, the three most common faults on 12 volt systems are:
1) bad 'ground' connection;
2) bad 'ground' connection;
3) bad 'ground' connection.

A very small prize awaits the person who can correctly guess what the fourth most common fault is caused by.........

[hankaye]

MtnDon & aggie79, Howdy;

12 volt DC, negative all goes to the metal frame. Mainly because it's there and you don't have to run another wire. The positives get fused and switched.

.

This pops up every so often in a topic. Eventually relying on the frame for the negative conductor often results in more trouble and time expended in troubleshooting than the value of any wire saved. Running a negative DC wire to each light and device ensures a good complete circuit and makes for easier troubleshooting if problems develop.

+1

OK, ground each separately, where do the separate grounds get attached to I think is the main question the OP had ...
what are your suggestions for that?

hank

[Padilen]

I bought a "buss bar" all negatives will connect to it and it will be connected to battery. Battery will be grounded to frame. AC will be grounded to frame also, I'm my case that's an aluminum frame. Is that correct? I also want to know if I can use the same contact point for AC &DC or should I separate ?

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ImageUploadedByTapatalk1442506360.194521.jpg (245.17 KiB) Viewed 2686 times

[troubleScottie]

It does not matter if they are exactly at the same point. It might be useful to have separate connectors so both system do not fail at the same time.

If you have a frame with sections -- several pieces mechanically assembled with screws or bolts, I would advice connecting the grounds to the same piece. It is possible that not all frame pieces are not electrically connected to each other or worse have slightly different ground levels. A completely welded frame presumably is one continuous electrical level.

There are two schools of thought on grounding wires. One is to have common wire for every device eg lights including running lights and hence a single common ground for everything. The other is to use a frame ground at or near the end point eg ground the running light to the frame at the light. The later assumes that all points on the frame have the same ground level. And saves a bit on wiring. Technically both should work.

As an observation, while working in an electronics lab, we found that two adjacent AC sockets had different ground levels. It caused all sorts of issues when designing and testing a communication protocol dependent the voltage difference from ground.

[Padilen]

Thank you.

[OverTheTopCargoTrailer]

OMG

Now I need to start over, I have 2800 watts solar , 2000 ah lithium and I don't have an ac or dc ground to the mostly wood frame

[MtnDon]

OK, ground each separately, where do the separate grounds get attached to I think is the main question the OP had ...
what are your suggestions for that?

hank

Run to a buss bar as padilen suggested. Some, not many, DC fuse blocks will have a negative buss. Most that I see do not. That makes it as easy as it can get as then the + and - originate in more or less the same place.

[Gerdo]

12 volt DC, negative all goes to the metal frame. Mainly because it's there and you don't have to run another wire. The positives get fused and switched.

.

This pops up every so often in a topic. Eventually relying on the frame for the negative conductor often results in more trouble and time expended in troubleshooting than the value of any wire saved. Running a negative DC wire to each light and device ensures a good complete circuit and makes for easier troubleshooting if problems develop.

+1

You caught me. Since most of most TDs are non metal, running a pair of wires is usually the best thing to do for 12 volt use.
And thinking back, yes that is what I did with mine.

[Padilen]

I bought a "buss bar" all negatives will connect to it and it will be connected to battery. Battery will be grounded to frame. AC will be grounded to frame also, I'm my case that's an aluminum frame. Is that correct? I also want to know if I can use the same contact point for AC &DC or should I separate ?

Pic of bar

ImageUploadedByTapatalk1442506360.194521.jpg

I should have wrote this down when I bought wire. cause I'm short this wire.
Also the terminal block I bought for positive is crap. Just connecting wires from PD4045 I broke 2. I looked at the rest and they break at a seam or mold line. I'm waiting on my friends crimp tool to get my AC grounded and my DC hooked to battery and grounded.
I'm pasting this to my build thread.