Replaced the Univolt where does the white wire go?

[RichHog]

So putting in a new Boondocker and Blade fuse panel . On the Univolt there’s a white thick wire. Not sure what it is and where it goes labeling says LOAD White.

[AtomicNo13]

I believe that drives the power light on the monitor panel. Somewhere here are the instructions for making that work with a replacement converter. I did mine so long ago I can't remember the schematic.

[kb0zke]

Rich, do you have a circuit tracer device? Can't think of the proper name right now, but you put a transmitter on one end of the wire and "listen" with a probe where you think the other end might be. When you touch, or at least get really close, to the right wire you will hear a sound (and maybe see a light) from the probe. One of those might help you find the other end.


If the power light on the monitor panel is fairly close, you can use a regular VOM to verify that that's what it is.

[dbj216]

Univolts had, and most converters have two circuits: the 120vAC going in to power the thing, and the 12DC going out.

There are also two ways to power the four 12vDC circuits in your trailer. (Purple, yellow, pink, brown). You power them with your 12v battery, or you power them with your 13.5v converter. Your converter will connect to the fuse panel too. Mine connects from the rear of the fuse panel. The higher voltage wins the race and provides the power to the trailer automatically. Your battery will get a rest and get charged up too when running on the converter. Heck, you can even remove the battery and your 12vDC circuits will just run happily off the converter (when plugged into shore power of course.)

Your picture of the old fuse panel shows a lug labeled White, Load. I also see where the "Red Battery +" wire would connect to the fuse panel. I believe these are the connection points to the fuse panel from your battery wires.

Anyway, as mentioned, you need to follow the wiring out of the old Univolt to find out where it goes.

Always verify any information given in these Forums. I want to help you, but I may be mistaken. I trust others will chime in and provide verification or correction.

David

[TG Twinkie]

The white wire is the common/ground side of the 12 volt DC circuit.
The black or negative lead from the battery connected to the left side of the shunt in the pic. The white wire on the right side of the shunt connects to the coach frame as well as the - output of the Univolt. Look on the back side of the old fuse panel. I believe you will find the negative wire of the Univolt is connected to the same point as the white wire. The shunt is only there because there may have been or is an ammeter showing the load on the system.
Assuming you are replacing the original fuse panel with something modern. You will need to provide a common place to connect the battery negative, the new converter negative and the chassis ground.
If you want to retain the shunt it will require mounting on an isolated surface.

[RichHog]

I’ve got all of the 4 12 volt circuits running off the Boondocker and have lights etc. but that was running an extension cable from the house vrs the trailer shore power cable. Just not sure what the white one dies but it’s a thick 10 or 8 gauge wire like the battery lines or Boondocker.

[TG Twinkie]

Originally Posted by RichHog

I’ve got all of the 4 12 volt circuits running off the Boondocker and have lights etc. but that was running an extension cable from the house vrs the trailer shore power cable. Just not sure what the white one dies but it’s a thick 10 or 8 gauge wire like the battery lines or Boondocker.

RichHog.
Check my response above.

[RichHog]

So the white wire goes to the trailer ground? Kind of thought so. The fuse panel is a PD5000. So white goes to the ground (green) bar?

[TG Twinkie]

Originally Posted by RichHog

So the white wire goes to the trailer ground? Kind of thought so. The fuse panel is a PD5000. So white goes to the ground (green) bar?

There is a common/ground buss bar (silver colored) on the back. It has multiple screws.
I believe the green termination is the earth ground connection for the AC side of the converter.
The manual on the PD 5000 should clearly point out the proper connection points.

[absteen]

In House wiring, the white wire is hot, and load means it carries the power to lights, outlets , and other devices. I am not familiar with the "boondocker", but code wise white is HOT.
Andrew, K6STN
2017 27'FB International
2017 F-250 4x4 Lariat crew cab diesel

[pmclemore]

Richhog, you'd better find an expert. I seem to recall that the white in Airstreams is the hot one, too. But find a real expert.

Pat

[Kvsterling]

So I am currently re-wiring a “classic airstream motorhome” 1984 (inner skins removed). I can attest that the 12v dc system (that generation) used white stranded wire for DC (-). They are all merged somewhere behind the wall to a thicker white wire which goes to the fuse panel. This is then chassis-grounded. I would guess is approximately 6 gage although I am upgrading. The Colored wires are (+) out to your components. For your white wire, try this...remove one of the electrical component (switch/light), you will have + and - leads. You can check if your white wire is - by testing/connect the - lead and your white wire with an ohmmeter. If it reads “0”, jackpot! Just to confirm, I would also recommend testing + from battery bank(not connected) to the white wire to confirm this is not your main + line. Ohmmeter should remain “1”. Remember, disconnect all power supplies when testing this stuff!

[DremStremer]

Originally Posted by Kvsterling

So I am currently re-wiring a “classic airstream motorhome” 1984 (inner skins removed). I can attest that the 12v dc system (that generation) used white stranded wire for DC (-). They are all merged somewhere behind the wall to a thicker white wire which goes to the fuse panel. This is then chassis-grounded. I would guess is approximately 6 gage although I am upgrading. The Colored wires are (+) out to your components. For your white wire, try this...remove one of the electrical component (switch/light), you will have + and - leads. You can check if your white wire is - by testing/connect the - lead and your white wire with an ohmmeter. If it reads “0”, jackpot! Just to confirm, I would also recommend testing + from battery bank(not connected) to the white wire to confirm this is not your main + line. Ohmmeter should remain “1”. Remember, disconnect all power supplies when testing this stuff!

That's how my '70 Safari is wired. The white wires are merged to one thick wire that attaches to the Univolt.

[TG Twinkie]

The white wire in residential systems is the neutral. If the device is wired properly the white wire is NOT hot.
One needs to understand the differences between the 120 volt AC system and the 12 volt DC system in their RV.
The white wire in an RV 12 volt DC system is NOT the same as the white wire in a 120 volt AC system.
Back in the last century some genious decided to make the white wire the negative side of an RV 12 volt DC system. Then to make the black wire the positive side of an RV 12 volt DC system.
IMHO they should have stuck with the automotive industry standard. Red is positive, black is negative.
Since in most cases the black wire in an RV is the charge line from the TV.
Now that we have to deal with white and black in RV 12 volt DC systems. We need to learn and understand the following.
In an AC circuit the neutral wire is white. The neutral wire is not ground.
The neutral wire under normal circumstances is NOT hot.
The black wire and or the red wire in AC systems (are) the hot wires.
GREEN or BARE is ground in AC system.

THERE ARE NO "HOT" WIRES IN AN RV DC SYSTEM.. IMHO

There are only POSITIVE and NEGATIVE wires or sides to a DC circuit.
The term "ground" is misleading in a DC circuit. The proper term IMHO is "common".
The white wire in a DC system is "common" to all DC devices in an RV.
It is 1/2 of the DC circuit whether it be an actual white wire or the chassis or skin of the RV. Unfortunately the more frequently used term for this side of the circuit is "ground". Making things even more confusing.
To add to the confusion. Most 12 volt devices for RV's like water pumps etc. Have red and black wires. Red being positive, Black is negative.
Again. A thorough understanding of the difference is critical.

[RichHog]

Originally Posted by TG Twinkie

The white wire is the common/ground side of the 12 volt DC circuit.
The black or negative lead from the battery connected to the left side of the shunt in the pic. The white wire on the right side of the shunt connects to the coach frame as well as the - output of the Univolt. Look on the back side of the old fuse panel. I believe you will find the negative wire of the Univolt is connected to the same point as the white wire. The shunt is only there because there may have been or is an ammeter showing the load on the system.
Assuming you are replacing the original fuse panel with something modern. You will need to provide a common place to connect the battery negative, the new converter negative and the chassis ground.
If you want to retain the shunt it will require mounting on an isolated surface.

Here’s a pic of the old Univolt as wired. Still not sure what to do to get the control panel working and I guess I need a bus bar to connect the blue battery charge line with the + red off of the battery.

[RichHog]

I will check the white with an ohm meter. I don’t see an official ground to the frame wire in this yet so maybe this it. There is a heavy bare ground wire over under the toilet floor i need to reconnect. Not sure if it goes to the ac main breaker panel but I’m guessing it does and will check.

[TG Twinkie]

Originally Posted by RichHog

Attachment 336104
Here’s a pic of the old Univolt as wired. Still not sure what to do to get the control panel working and I guess I need a bus bar to connect the blue battery charge line with the + red off of the battery.

I would use a stand alone fuse holder and use the same size fuse as the Univolt. Then connect the load side of the fuse to the positive side of the system. The following will be connected together in some fashion.
House battery positive.
Converter positive.
Fuse panel positive.
Charge line from TV positive.

In order to get the ammeter to function you will need to wire the shunt in series with the negative side of the system. Along with running 2 wires (which should exist) to the shunt from the meter. Note the 2 small (red and black) at the bottom of the shunt.
I don't have a control panel in my coach. So can't be of help there. Don't know what is on an old control panel. If you use the shunt it must be mounted on an isolated surface.

[RichHog]

So the Airstream service manual says the White wire is the Negative Load. So does that mean ground to frame? Also I’m thinking the small red plug in wire is the 12v power to the control center and black plug in wire the ground to control center. Any thoughts from the audience?

[TG Twinkie]

Originally Posted by RichHog

So the Airstream service manual says the White wire is the Negative Load. So does that mean ground to frame? Also I’m thinking the small red plug in wire is the 12v power to the control center and black plug in wire the ground to control center. Any thoughts from the audience?

The small black and red wires which are connected to the shunt are for the ammeter only. They are not power wires.
You may want to check what wire is connected to the 4 amp fuse at the lower right corner. It may be for powering the control panel.
Can you follow the large white wire? It probably goes to the frame.

[RichHog]

The wire (Grey) from the little fuse is for the power on light. I have the trailer manual and the service manual that shows schematics. But it is still difficult to trace out where the wires go and what they do.