PD4045 Installation

[bushido41]

Hello Everyone,

I have a PD4045 installed on my TTT, the AC side works great, but I have a few questions about the DC side.
1. The installation manual(which has a lot to be desire) mentions to connect the negative side directly to the PD4045. What happens to chassis ground?
2. The battery connection wires are 10 AW, a bit thin for my taste, when we are talking direct connection to the battery. I know the PD4045 is rated for 45 Amp but just curious.
3. Do you guys recommend a cutoff switch?

My main concern is the negative side connection of the battery, connect directly to chassis or PD4045?

Thank you in advance for your comments.

[8ball_99]

You need to connect a ground to the frame of the trailer.. Now you can connect the converter straight to the battery and then have a ground from the battery ran to the frame or you can ground the battery and just ground the converter to the frame,, Either way does the same thing.. I have my converter connected straight to my batteries and I have large gauge wire connected to the frame of the trailer.. You have to have the battery connected because for example if you have a light thats grounded to the frame and just the positive is connected to the battery the light won't work if the batteries ground is not connected to the frame somewhere..

You don't have to have a switch or disconnect, But you do need a fuse close to the battery between it and the converter.. I used a marine breaker because one if it trips for some reason I can just reset it. But also because you push the button on it to open the breaker so it also can work as a disconnect if needed.. The converter also should have a built in fuse for the battery connection. So for some reason you want to break the connection between the converter and the battery you can also just pull that fuse.

[bushido41]

Hello 8Ball,

Thank you for the reply and the information. I will follow your advise and configure accordingly.

Thank you,

Ed

[Shadow Catcher]

A ground to the frame is necessary only if you ground lights etc to the frame, a not so good idea. Our PD is not grounded to the frame and all lights are wired positive and negative. Why no frame ground, you are asking for problems down the road when corrosion sets in and that ground is making a poor connection.
Maximum power for 10Ga is 55A according to the American Wire Gauge and AWG table and that is what I have used in ours. There is a 14" distance between the PD and the battery. One thing to remember is that the 45A is the rating, but peak inrush is 32A and it is fused for 30A output.
Cut off switch for DC absolutely. Ours is turned off when ever we travel, think potential short.

[S. Heisley]

Hello Everyone,

I have a PD4045 installed on my TTT, the AC side works great, but I have a few questions about the DC side.
1. The installation manual(which has a lot to be desire) mentions to connect the negative side directly to the PD4045. What happens to chassis ground?
2. The battery connection wires are 10 AW, a bit thin for my taste, when we are talking direct connection to the battery. I know the PD4045 is rated for 45 Amp but just curious.
3. Do you guys recommend a cutoff switch?

My main concern is the negative side connection of the battery, connect directly to chassis or PD4045?

Thank you in advance for your comments.

I'll tell you what I believe, based on my WFCO 35 Amp experience and research/reading, and maybe it will help:

1. Although some may argue, it is my understanding that the chassis ground is basically for the AC side of things. It has further been suggested that it is a good idea to let at least one of your hitch chains dangle down and touch the ground as well, when plugged into shore power, to give you a better, even safer AC grounding. However, one ground going from the converter to the chassis should be enough, assuming this is done according to the instructions given in the installation manual. With that, the converter should be able to do what it needs for both the AC and DC.
2. For my 35 Amp, the installation manual specified 8 AW, which was a little thick and difficult to work with; but I used it. I think most people here use 10 AW for the battery connection and I haven't heard where anyone has had problems; but, most people don't use more than 35 Amps. Recognize that going with a bigger size wire shouldn't hurt anything but going with a wire that is too small might. Depending on how you plan to use your electrical system and how the PD charges your battery, you may want to research further on this before you decide. I suggest you call the manufacturer and ask them. Actually, both questions 1 & 2 can be answered by the manufacturer and probably should be.
3. Yes, it wouldn't hurt to have one. A cutoff switch can stop possible battery bleeding, when the battery is not in use and not being charged. If one of your switches goes bad/shorts, and you don't have a cutoff switch stopping discharge, you could find a dead battery, the next time you are ready to use your trailer. It is said that bleeding or otherwise allowing your battery to be drained until it is empty or down to less than 30% will shorten its usable life span.

...Hope this helps.

[bdosborn]

Maximum power for 10Ga is 55A according to the American Wire Gauge and AWG table and that is what I have used in ours.

Unfortunately, that table doesn't have much o do with the rating of wires that are easily available to home builders and shows a rating that is 25A over what over what most manufacturers would recommend. Wire ampacity is a function of insulation rating, ambient temperature and installation methods. The AWG table is worthless since it doesn't account for any of these issues.

Start here for ampacity of thermoplastic wire, which is typical of the type found at the home center. The 60C column would be the rating of wire for a typical trailer installation.

Southwire Specifications

Bruce

[mustangcats]

I did a lot of research before connecting my WFCO 45 amp power supply and it was advised not to connect the AC ground to the trailer chassis. The power supply panel in the trailer is basically a sub panel, with the campground electrical connection being the main power supply, and the ground is through the campground connection. Before plugging into the campground power, you should check it with a meter to make sure it is wired correctly and the ground is working. I also read that if the AC ground was attached to the trailer chassis and the trailer chassis was not grounded (remember it is on tires and the only part that touches the ground is the hitch jack which usually has a board under it) the trailer could become energized and you would get a shock if you touched the trailer.
As for the DC ground, that is coming from the negative terminal of the battery which is connected to the DC ground on the power supply. All the ground wires from the DC switches, outlets, etc. are all tied back to the DC ground connection on the power supply.
This is how I wired my trailer and it works perfectly.

[bdosborn]

I did a lot of research before connecting my WFCO 45 amp power supply and it was advised not to connect the AC ground to the trailer chassis.

Are you sure you're not confusing the neutral with the ground? Every RV manufactured has the voltage converter boned to the frame as its a code requirement:

NEC 551

(C) Bonding Voltage Converter Enclosures. The non–current-carrying metal enclosure of the voltage converter shall be bonded to the frame of the vehicle with a minimum 8 AWG copper conductor. The voltage converter shall be provided with a separate chassis bonding conductor that shall not be used as a current-carrying conductor.


I bonded my converter to the frame and it works perfectly. I also don't have to worry about getting electrocuted by touching the frame if a hot wire somehow energizes it. The ground ensures that there is a low impedance path back to the breaker so it opens as soon as a hot wire touches the frame. An ungrounded frame will remain energized if a hot wire touches it. This means that you are the path to ground if you touch it and, unfortunately, you are a high impedance path and the breaker may never open.


Bruce

[mustangcats]

OK...I did some more research on the subject and there still is a lot of conflicting information. I have come to the conclusion that even though the ground goes back to the campground box, running a ground to the frame will provide an extra layer of protection in case something goes wrong. The one thing that did catch my attention today while doing the research was the issue of "hot skins", where the metal siding and parts of the trailer become electrically charged. I don't see how that can happen the way my trailer is currently wired and set up. However, I do plan to cut a hole in the wall to put in a small air conditioner. If something should go wrong with the a/c, I see that the metal case of the a/c could transfer an electrical charge to the siding. Then the current would go to the frame and back to the ground at the service box and trip the breaker...right? But what if the ground at the electrical box was defective? I guess you'd still get a shock. Or would the breaker inside the trailer trip? It seems to me that the only way to be totally safe would be to drive a metal rod into the ground and connect it to the frame...not very practical when a trailer is always being moved.

[H.A.]

[

[8ball_99]

You always bond the ground from AC to the the frame.. That way if you have a hotwire make contact with the frame the current has a path to ground.. If you don't do this and a hotwire contacts the frame when you step in our out of the trailer you could become the path to ground.. As far as the 12v goes no you don't have to run a ground wire from the battery to the frame if you run ground wires directly to every 12v fixture.. In a small trailer with just a few lights its probably not a big deal to do it that way.

[bdosborn]

You always bond the ground from AC to the the frame.. That way if you have a hotwire make contact with the frame the current has a path to ground.. If you don't do this and a hotwire contacts the frame when you step in our out of the trailer you could become the path to ground..

Isn't that what I said?

[bdosborn]

A few posts above suggest letting the safetychains drape upon the earth as added grounding safety.
While its a fair idea and shows a users concern, At best its an urban legend / campground myth.
In reality would be so minimally effective to be not at all helpful as an added chassis grounding.

In fact it would do absolutely nothing at all to reduce the touch potential, just as a ground rod at the trailer wouldn't do anything. Here's why:

Touch Potential and Ground Rods

I also test the outlets at a campground to make sure the ground is present and the hot and neutral haven't been swapped. The ground wire is the first line of defense against electric shock (in this country, it's completely different in Europe).

Bruce

[bushido41]

Thank you everyone for your commentaries and suggestions. I sent an email to Progressive Dynamics for their official installation configuration. What Im concerned is about creating ground loops and also creating a ground differential. As many of you know ground is relative and you can have two separate devices grounded and have a voltage differential that can zap you if you touch both at the same time. The concern here is the TV is grounded to the chassis, negative on the battery is connected to chassis, then the 7 pin connector is connected to the TTT which battery is also connected to grounded to the chassis. In addition some of you also are suggesting to connect the neutral on the AC side from the campsite pole to chassis. I do not feel comfortable with that suggestion, since first PD does not show that on the installation manual , which has a lot to be desired.

I hope I can get a response from PD soon and I will pass their comments to all of you. I know we have some RV techs in the forum, like Martian from Canada. I was wondering what is their stan on this subject, which if installed incorrectle can cause a loss of money or even worse of life.

Thank you,

[bdosborn]

The neutral should never be connected to ground in a trailer. The neutral and ground should be separate from the campground pedestal all the way to the end device. I went back and re-read the posts, which one gave you the impression they should be tied together, was it mine? I need to edit it if it did.


Bruce