Electrical wiring help needed

[rubicon327]

Originally Posted by rubicon327

Thanks Tom. Can’t thank you enough. I double and triple checked that I’m wired equivalent to your schematic.

I realized that I never included my final schematic sketch. Red hashed lines are wires/items removed. It's crude but you'll get the picture. The wiring is functionally equivalent to Tom's much nicer diagram he provided earlier in the thread.

[Brian B-P]

Originally Posted by rubicon327

I realized that I never included my final schematic sketch. Red hashed lines are wires/items removed. It's crude but you'll get the picture. The wiring is functionally equivalent to Tom's much nicer diagram he provided earlier in the thread.

If I am reading this correctly, it does not show the change to the power for the breakaway system as discussed earlier.

Again if I am reading it correctly, the only connection between the negative of the 7-way towing cable and the negative of the trailer's system is through the frame; Tom's drawing (in post #2) shows the same. Is there really no direct (not through the frame) path from tow vehicle negative to battery negative?

[rubicon327]

Originally Posted by Brian B-P

If I am reading this correctly, it does not show the change to the power for the breakaway system as discussed earlier.

Again if I am reading it correctly, the only connection between the negative of the 7-way towing cable and the negative of the trailer's system is through the frame; Tom's drawing (in post #2) shows the same. Is there really no direct (not through the frame) path from tow vehicle negative to battery negative?

Brian: The breakaway change is shown. Its the red line to the battery side of the disconnect switch. Always hot.

Yes it appears the trailer 7-pin negative is only a frame ground. Could be easily remedied if I take a new wire from the power center ground stud and land it on the metal junction box with the white ground wire from the 7-pin. Everything is operating well right now. Is this best practice?

[tdf-texas]

Originally Posted by Brian B-P

If I am reading this correctly, it does not show the change to the power for the breakaway system as discussed earlier.

Again if I am reading it correctly, the only connection between the negative of the 7-way towing cable and the negative of the trailer's system is through the frame; Tom's drawing (in post #2) shows the same. Is there really no direct (not through the frame) path from tow vehicle negative to battery negative?

If you think about what devices are getting power from the tow vehicle (TV), it makes sense to use the trailer frame for the negative return since the TV frame is the negative common for the TV. The brake lights, turn signals, and trailer brakes all get powered from the TV (the only exception is the emergency brake circuit which uses the trailer battery) and all of them use the frame as the negative return.

Adding a negative wire from the WFCO ground lug to the 7-pin ground connection might help with the TV charging the trailer battery but the 7-pin ground would still have to be there for the brake lights, turn signals, and trailer brakes to work.

[John in Santa Cruz]

A rule of electronics is to avoid duplicate ground paths, which would create a ground loop. The frame and the trailer DC negative should only be connected at one point.

[Brian B-P]

Originally Posted by tdf-texas

If you think about what devices are getting power from the tow vehicle (TV), it makes sense to use the trailer frame for the negative return since the TV frame is the negative common for the TV. The brake lights, turn signals, and trailer brakes all get powered from the TV (the only exception is the emergency brake circuit which uses the trailer battery) and all of them use the frame as the negative return.

Adding a negative wire from the WFCO ground lug to the 7-pin ground connection might help with the TV charging the trailer battery but the 7-pin ground would still have to be there for the brake lights, turn signals, and trailer brakes to work.

Yes, the 7-pin negative wire needs to connect to the battery negative and the frame; it doesn't need to connect to the battery only through the frame.

It's unfortunate that Escape at some point downgraded from fully wired lighting returns to connections via the form, but even worse if charging from the tow vehicle is forced to use that as well.

It would indeed make sense to use the frame, with a proper frame connection. Maybe it's worth the effort to fix that connection at least at the 7-pin connection and the battery if not at every point a self-tapping screw might have been stuck in the frame.

[Brian B-P]

Originally Posted by John in Santa Cruz

A rule of electronics is to avoid duplicate ground paths, which would create a ground loop. The frame and the trailer DC negative should only be connected at one point.

I think that rule is out the window the moment you use the frame, since the frame itself is a multi-path system of conductors, not a straight bus. A wire from the 7-pin cable negative pin to the battery is just another path, like another crossmember.

Fortunately, it's a RV DC power system, not a radio-frequency signal system.

[John in Santa Cruz]

Originally Posted by Brian B-P

I think that rule is out the window the moment you use the frame, since the frame itself is a multi-path system of conductors, not a straight bus. A wire from the 7-pin cable negative pin to the battery is just another path, like another crossmember.

the frame carries all the vehicle loads, brakes and exterior driving lights.
the RV system carries all the camper/house stuff. they should be tied together at only one spot. the only current through that ground connection should be the ground return from the tow vehicle charging the trailer battery while you're driving.

Fortunately, it's a RV DC power system, not a radio-frequency signal system.

fer sure.

[Brian B-P]

Originally Posted by rubicon327

Brian: The breakaway change is shown. Its the red line to the battery side of the disconnect switch. Always hot.

It's always hot... unless the fuse blows. I thought the idea in the discussion was to go directly to the battery to bypass that fuse; I probably misunderstood.

Originally Posted by rubicon327

Yes it appears the trailer 7-pin negative is only a frame ground. Could be easily remedied if I take a new wire from the power center ground stud and land it on the metal junction box with the white ground wire from the 7-pin. Everything is operating well right now. Is this best practice?

Yes, avoiding poor frame connections is certainly a good idea; however, as long as those connections work there's no problem. Cars use "frame" (body) connections with no issues, but those connections are made properly.

[RangerMan]

Originally Posted by tdf-texas

I followed your lead and installed a ground buss directly above the WFCO. Moving the negative return wires from the stud to the buss used up all twelve grounding screws. So, if I need to add more circuits - I will have to upsize the buss or put them on the stud. Here's the buss I used.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

The grounds now have a much better place to land!

Thanks, Jon.

I checked my WFCO gnd stud and it was difficult to count but it appears there are at least 7 wires stacked on that thing. Did you have to 'adjust' any wire lengths or connectors to attach to the bus? No slack at all in the wires but should not be a problem if the bus is attached above the WFCO cause all the wires, save one, come from above.

I haven't added anything. All the wiring is ETI installed.

[RangerMan]

Originally Posted by tdf-texas

I followed your lead and installed a ground buss directly above the WFCO. Moving the negative return wires from the stud to the buss used up all twelve grounding screws. So, if I need to add more circuits - I will have to upsize the buss or put them on the stud. Here's the buss I used.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

The grounds now have a much better place to land!

Thanks, Jon.

I checked my WFCO gnd stud connectors again to decide on a bus. I looked very closely this time and could see space between 3 of the ring connectors. Tiny but still space. The ring connectors were not completely compressed on the stud. These connections should be gas tight!

Not easy to do with 7 connectors on the stud.

[tdf-texas]

Originally Posted by RangerMan

I checked my WFCO gnd stud and it was difficult to count but it appears there are at least 7 wires stacked on that thing. Did you have to 'adjust' any wire lengths or connectors to attach to the bus? No slack at all in the wires but should not be a problem if the bus is attached above the WFCO cause all the wires, save one, come from above.

I haven't added anything. All the wiring is ETI installed.

As you mentioned, all the wiring comes from above the WFCO so I had sufficient wire length to attach to the negative buss bar. The only wire I had to add was the one that goes from the buss bar to the WFCO ground stud.

After the negative buss bar install, The WFCO ground stud had four wires left - one to the new buss bar, one to the battery negative post, one to the solar charger negative, and one to the trailer frame ground.

[John in Santa Cruz]

there's nothing wrong with stacking ground wires on a single stud. I'd put the heaviest gauge wires on first, and the lighter gauge ones on top, but either way, they all make contact. Note that stud is just a mounting point, it itself is not a ground, other than via the wires connected to it.

I do plan on moving my 'main' ground point over to the black bus bar I added, and keeping the smaller grounds on the existing post, but it kind of hinges on the chassis ground wire and the converter ground wires reaching my bus bar, which is a few inches over. Currently my ground bus bar is connected to the WFCO ground stud with a very short 4 AWG wire.

[CharlesinGA]

Your friendly neighborhood Bigfoot owner here, again. Since you are talking grounds, here is the mess that Bigfoot made when they used a ground bar to make all of the grounds (good idea in practice), and the second pic is what it looked like after I got through making a new mounting bracket for the ground bar to rotate it 90° and installing ferrules on all of the wires.

Charles

[CharlesinGA]

Just a couple more for a better view. This is all under a dinette seat, behind the Parallax power panel with a PD4645 converter/fuse panel.

Charles

[mfschu]

Looks excellent! How long did that take you? Nice Job!

[CharlesinGA]

Originally Posted by mfschu

Looks excellent! How long did that take you? Nice Job!

Are you referring to my ferrules? A piece of aluminum extrusion L material to make a new bracket out of and an hours work to cut and drill and file. I matched it to the holes in the floor so as to not put any more holes than possible in it. Installing the ferrules is fairly easy, cut the wire clean and strip and carefully slip the ferrule over making sure to not miss any strands. Then crimp them. I bought two crimers one does Hex crimps and one does square crimps. The grounds were all hex crimps.

I think I spent most of a day on my hands and knees doing the work. It was just so bad from the factory it was pitiful.

On the fuse panel, I had installed the PD 4645 converter earlier and just fitted the wires under the square plates under the screws. They are designed to accept bare wires, and initially I used ferrules but realized it was forcing the screws sideways so I switched to the fork terminals instead.

The ferrule crimpers were fairly inexpensive but came with ferrules that were crap for my purposes so I located an outfit called https://www.ferrulesdirect.com/ and ordered the ferrules from them as I could get the exact length and diameter I needed.

The black box next to the ground bar is the generator automatic transfer switch (ATS) for the 2500LP Onan under the trailer, and the silver box in the top of the 6th pic is a load shed box that powers the water heater but disconnects it in favor of the microwave. Both WH and MW are on the same circuit breaker that feeds thru the load shed box. Pretty common, My Winnebago motor home came from the factory with one.

The blue smurf conduit (ENT) carries stranded THHN 10 gauge from the outside power inlet to the ATS and from the ATS to the back of the power panel (what you see in the pic) and also from a junction box on the floor above the generator to the ATS. The stranded THHN wire is MUCH easier to work with than solid 10 gauge Romex which is horrible to deal with.

The shore cord was originally hard wired to the power panel and for the generator you had to manually plug the shore cord into a receptacle inside the shore cord's storage compartment to make the connection. Thats great setup and very simple, my motor home had a similar setup, but this storage compartment was tiny and with the shore cord stowed in it, was so packed it was all but impossible to get your hand in it to plug the shore cord into the receptacle. I removed the storage compartment and put an aluminum plate on the outside with the power inlet in it, so I had to install the ATS for everything to work.

Charles

[mfschu]

Nice work, photos, and write-up! Thanks for sharing your experience to help the rest of us!