Did you ground your PD 9200 series converter?

DrewE,

Thank you. That makes sense.

wgriswold wrote:

kellertx5er wrote:

wgriswold wrote:
OK, I am going to display my ignorance, but here goes.

Is the AC ground to earth connected to the frame? I think so but am not sure.

My understanding is that the AC ground to earth is connected to the case of the convertor via the plug. So it seems that there would be no need for an additional ground to earth via the frame.

Why is the DC negative wire also wired to the frame which is also part of the negative circuit of the 12V system?

Maybe it is important to connect the negative component of the DC system to the earth ground of the AC system?

Thanks for helping me understand this.

As stated previously in this thread, NEC Art. 551.20(C) requires the enclosure of a converter to be connected to the vehicle frame with a minimum #8 copper conductor. Period, end of issue.

Yes, I read the thread. I am wondering why this is required. Of course, I would follow requirements of code, but I wanted to understand why.

Thanks for all the answers. I still don't understand why two grounds are necessary in the AC side and two paths to negative side of battery are required in the DC side.

AC safety ground and DC ground (negative) are both tied to the frame of the RV.

I think the idea is that if the normal current carrying negative wire to the battery were to fail somehow, you would potentially have the entire DC current flowing through the safety ground on the AC side if the converter were not separately bonded to the vehicle frame. The safety ground is only sized to carry the fault current of the AC input, which would be limited to 15 or 20 A for a normal plug. Since the converter can put out several times that current, that would be a significant overload of the safety ground wire and could very well start a fire.

If the DC output of the converter were isolated (in the converter) from the frame or ground, presumably the extra bond would not be required for safety, though the code may not make such a distinction. If nothing else, such isolation could also break down without it being evident so long as the normal negative DC connection is unimpaired.

kellertx5er wrote:

wgriswold wrote:
OK, I am going to display my ignorance, but here goes.

Is the AC ground to earth connected to the frame? I think so but am not sure.

My understanding is that the AC ground to earth is connected to the case of the convertor via the plug. So it seems that there would be no need for an additional ground to earth via the frame.

Why is the DC negative wire also wired to the frame which is also part of the negative circuit of the 12V system?

Maybe it is important to connect the negative component of the DC system to the earth ground of the AC system?

Thanks for helping me understand this.

As stated previously in this thread, NEC Art. 551.20(C) requires the enclosure of a converter to be connected to the vehicle frame with a minimum #8 copper conductor. Period, end of issue.

Yes, I read the thread. I am wondering why this is required. Of course, I would follow requirements of code, but I wanted to understand why.

Thanks for all the answers. I still don't understand why two grounds are necessary in the AC side and two paths to negative side of battery are required in the DC side.

wgriswold wrote:
OK, I am going to display my ignorance, but here goes.

Is the AC ground to earth connected to the frame? I think so but am not sure.

My understanding is that the AC ground to earth is connected to the case of the convertor via the plug. So it seems that there would be no need for an additional ground to earth via the frame.

Why is the DC negative wire also wired to the frame which is also part of the negative circuit of the 12V system?

Maybe it is important to connect the negative component of the DC system to the earth ground of the AC system?

Thanks for helping me understand this.

As stated previously in this thread, NEC Art. 551.20(C) requires the enclosure of a converter to be connected to the vehicle frame with a minimum #8 copper conductor. Period, end of issue.

Repeat from earlier post--the 120v cord going into the converter chassis box has its ground wire going to the back of that "chassis ground" lug inside the box. The lug has another lug on the back of it for inside. (It is the same with inverters only in reverse)

So the main 30a shore power cord comes in and its big bare copper wire is grounded to the frame, the hot goes to the 30a main breaker, and the neutral goes to the N bus.

The receptacle circuit the converter plugs into is three prong with the ground prong to the frame using that same big copper wire back at the AC breaker panel. Now you run a wire from the chassis ground lug to the frame.

A built-in "lower portion" converter is not grounded like a deck mount because its chassis is touching the big power centre chassis which is grounded. The hard-wired 7355, eg has only the H and N, no ground wire for its 120 side but its chassis is touching the big power centre chassis it is inserted in as the "lower portion".

My 2000w Vector inverter has a warning not to run the chassis ground over to its DC neg input. (Same as the PD converter warning only in reverse) It has to have its own wire to the frame. (Even though the inverter's neg input comes from the battery which is neg grounded to the frame. Unless the battery does nothing but power the inverter. Then it does not have to be neg grounded like with a battery powering the RV's 12v systems, many of which use the frame as the neg path)

The inverter manual says the chassis ground is to reduce radio and TV interference. it says nothing about safety reasons for the chassis ground. I don't know if the same applies to the converter's chassis ground.

The ground in the AC cord is not large enough to ground a fault on the output side of the converter.
Yes, the ground coming from shore power is connected to the frame of the rig or at least it is suppose to be.
The out put is considered to be a derived service.

OK, I am going to display my ignorance, but here goes.

Is the AC ground to earth connected to the frame? I think so but am not sure.

My understanding is that the AC ground to earth is connected to the case of the convertor via the plug. So it seems that there would be no need for an additional ground to earth via the frame.

Why is the DC negative wire also wired to the frame which is also part of the negative circuit of the 12V system?

Maybe it is important to connect the negative component of the DC system to the earth ground of the AC system?

Thanks for helping me understand this.

The ground on the cord is for the incoming 120 volt side of the converter. This ground goes directly back to the 120 volt source as required by the NEC. The ground for the case protects the DC isolated system as well as the potential, highly unlikely failure on the AC system.

First off, I agree it's better to play it safe and ground the PD9260C's metal chassis to ground.

However, for the sake of discussion, one has to wonder why PD elected to use a standard, 3-prong, grounded, 120 volt, consumer-type plug on their PD9260C. Use of this plug gives the "impression" it can be safely used in a temporary, portable, non-permanent environment (without a dedicated, separate ground wire). They do not use a 3-prong, consumer-type plug on their application specific units.

You can download the manual HERE

It shows two grounds - a chassis and a battery negative - and warns that they must be two separate wires.

My new PD4655 has the same setup as did the old Parallax 7500 I was replacing. I used the same wires that went to the Parralax for the PD4655.
They both end up going to the same place but two wires are used.