Install inverter with factory shore power

[alan0043]

Hi Everyone,

 

I am installing a Xantrex Freedom 1800 inverter. The truck has a factory shore power already installed. The brand of the shore power is a unit from Phillips and Temro, 15 amp. I want to keep the factory shore power. I understand that I will have to make a change to the incoming power. I will take the incoming power from the side of the truck to the AC input side of the inverter. From the AC output side of the inverter I will take this wire to the input side of the shore power unit. My understanding that the transfer switch in the inverter will know when the truck is plugged into shore power. I'm I on the right track ? Now for a question or too. I need to hook up the inverter to the batteries. The plan is to use welding cables. I will use the largest wire possible for a Xantrex Freedom 1800 inverter. I can remember a seminar at one of the rallies talking about installing inverters and shore power. The seminar talked about grounds on the trucks. Now for the question. Do I need to ground the inverter to the frame of the truck ? This ground would be on the 12 volt side. The manual shows on the 12 volt side, that one cable goes to the positive side of the batteries and then other cable goes to the negative side and one more wire goes to the frame. Is this correct for my application ?

 

Thank you for any help,

Al

[Dollytrolley]

I have a life-long heavy electrical guru named Huston and he can be a pain in the Keister at times BUT he knows DC AND AC in heavy duty equipment VERY well...

 

So when I was cobbling a 2Kw inverter in the Dollytrolley bunkhouse Huston browbeat me into installing a LONG 0000 ground cable in conduit no less.....

 

Huston contends a REAL ground cable is the CORRECT method to feed a inverter and anything less is......less...

 

So i bucked-up and ran the big ground cable and Huston is Happy and the inverter seems happy so...I am happy...

 

Drive on....(great grounds are ... happy grounds)

[Lou Schneider]

Running two large wires (+ and -) from the inverter directly to the battery is the way to go. You want a direct, very low resistance path between the inverter and batteries and relying on the truck frame to complete the circuit just won't cut it.

 

Don't forget to include a catastrophe fuse in the positive line, as close to the battery as you can practically get it. A catastrophe fuse is one rated higher than anything the inverter can normally draw, so it will only blow if there's a short in the wire between the battery and inverter.

[Yarome]

You want a direct, very low resistance path between the inverter and batteries and relying on the truck frame to complete the circuit just won't cut it.

 

Lou is correct.

 

Frame grounding should never be used for an inverters current carrying conductor (with the caveat that we're talking about more than just a little 400watt "plug and play" baby inverter). Wire directly to the battery. "Can" it work? Yes. Can it damage your inverter or cause "brown out" type affects that could potentially cause damage to electrical devices drawing from the same circuit? YES. Can a high demand "draw" potentially cause damage to other automotive components sharing the same ground? YES.

 

It's perfectly fine for automotive components with relatively low power requirements, however, your inverter is a completely different animal.

 

Welding cable is good stuff. 120v current will travel well.. 12v feeds to your inverter will not. Install your inverter as closely as possible to your batteries with appropriately sized cables. Your inverters positioning has the priority. Run your shore and output 120vac lines as needed since distance has practically no impact.

 

Your proposed wiring setup looks good. You're correct.. you're Xanny will detect and apply 120vac as needed.

 

12v ground? Your Xanny is neutrally bonded internally when shore power is off and/or in inverter mode. When incoming AC power is detected the bond is automatically broken.

 

Cable size? Size according to the maximum load capacity of your Xanny calculated for your required distance. Don't worry about what size it's "designed" to accept at the connection points. "step down" lugs are available for next to nothing. ie., if you need to run 00.. run it.. then use a step down lug to convert the 00 to the maximum size allowed at the connection points.

 

Kind of like a highway.. you may need bigger lanes for efficient travel. The on/off ramps are a secondary concern. Make sense?

[Yarome]

Huston contends a REAL ground cable is the CORRECT method to feed a inverter and anything less is......less...

 

Ummmmm....

 

No comment.

[RandyA]

You may be remembering the presentation I gave a few years back at the ECR? Anyway, the short version was caution about inverters and generators that bonded the designated neutral on the 120 VAC side to the truck frame along with the grounding (safety) wire. While it is true the practice of bonding will trip a fuse or breaker if a direct short (fault) occurs between the designated hot 120 VAC wire to the truck frame it also places the frame at a high enough voltage potential to give you a significant shock when standing on earth ground and contacting the metal frame of the truck. You see, we live in an AC world and coupling between the two occurs naturally - just like lightning. The key word here is designated - remember you have no true ground for AC unless connected to a properly grounded shore power outlet. Both sides of the output of an inverter or generator are actually hot in reference to earth ground so we pick one to be designated as neutral and the other to be hot - or it could be the other way around. Anyway, it is safer to NOT bond. Some inverters and generators have a floating neutral (good), some do not but the bond can be removed, and some have a bond that cannot be removed (bad). So, for the bad ones we isolate the case and grounding wire (remember, this is the AC side) by mounting on an insulated substance and NOT running a wire from the 120 VAC grounding U on the device to the the AC distribution system in the truck which, BTW, will safely become bonded when we plug into shore power where a true earth ground is present. To still allow a power disconnect should a fault occur it is wise to add a GFCI between the inverter or generator and vehicle 120 VAC connection. By not bonding we also keep the AC and DC systems isolated from each other which can either resolve or avoid interaction between the two systems and the creation of strange (unsafe) ground loops. Final analysis - do not connect the inverter/generator grounding or safety wire, which includes the case, to the vehicle frame if there is a bond between the designated neutral and the grounding (safety) wire. There should never be a connection between the truck frame and either of the power providing wires from an inverter or generator when not connected to shore power. If there is no bond in the inverter or generator, connecting the case/grounding/safety wire to the vehicle frame is OK.

[Scrap]

If you haven't bought your inverter yet you can get one with your factory locking connectors on the front of it. You then unplug your incoming shore power plug from the Cab Power box (ie: loadcenter) and plug it into your inverter. Then you buy a "interior wire harness" that goes from your inverter to your Cab Power box. Now your AC is covered with all the factory locking connectors and you don't have to do any hand wiring or splicing.

 

For the shore power you currently have with the interior wire harness listed that you need to get:

http://www.phillipsandtemro.com/userfiles//CabPowDataSheet.pdf

 

For the individual part #'s of the inverter system and how they want you to wire it. Note that you would be using your existing load center and receptacle harnesses instead of the Y-splice and extensions in their diagram.

http://www.phillipsandtemro.com/userfiles//CabPowPlusDataSheet(1).pdf

 

All of the individual part numbers listed on their sheets are available from truck dealers. You don't have to buy the whole box that comes with half the stuff you already have.

[alan0043]

Hi Everyone,

 

Thank you guys for the help. It is nice knowing that I am going in the right direction. I will not ground any 120 volts to the frame of the truck. I will use the factory shore power ground the way that it is designed. I will add the equipment ground for the inverter like the instructions show. I will keep the lead wires as short as possible. There is a place here in town that can make the leads that I need. They use welding cable to make their leads.

 

Al

[RandyA]

Hi Everyone,

 

I will add the equipment ground for the inverter like the instructions show.

With the inverter you have selected, the equipment ground is OK since the Xantrex Freedom 1800 is not internally bonded. For some reason the model of inverter you are using didn't register when I first responded. Anyone installing a "truck stop" inverter or synchronous generator should check for a bond and if one is present either remove it or isolate it from the truck frame.