30 amp electrial and State Park GFI

[Sean]

... how to keep our SW4024 from tripping them (disconnect the filter capacitor).

Sean, how does affect the inverter?

It won't affect the inverter at all.

What might be affected is anything sensitive to RF interference, such as AM radios.  The capacitor in question is intended to reduce RF noise generated by the inverter that affects other sensitive devices.

...
Even is you incorporate the neutral ground bonding relays per Trace all you end with is a relay race in which the GFI trips before the relays can respond with correct bonding setup.

This is a separate problem, and there are several workarounds.  For a long time, we'd slip a dollar bill between the contacts of the bonding relay while we hooked up the power.  As soon as the power was connected, the relay opened, the dollar bill fell out, and we were good to go.

Eventually I got tired of opening the ATS enclosure (where our bonding relay lives) every time, and I made myself a special "adapter."

Here is where I have to say, like the Mythbusters, "Don't try this at home: I am a trained professional."  Specifically, the adapter in question is definitely not "to code."  It is, however, "temporary" and intended only to fix this specific problem.

What I did was to make a 4" long adapter with a standard 20-amp receptacle on one end (NEMA 5-20R) and a mostly standard 15-amp plug on the other end (NEMA 5-15P).  I took my Dremel and cut 3/8" off the ground tang of the plug.  This makes the ground tang, which is normally just a tad longer than the hot and neutral tangs, now a tad shorter than those tangs.

When I need to hook up to a GFCI, I first put this adapter on the end of my 20-amp shore cord (yes, I carry a separate, 10-gauge, three-wire, 50' cord for connecting to distant 15-, 20-, and 30-amp receptacles), connect the cord to the coach, and then plug in to the GFCI receptacle.  Since the hot and neutral now make contact first, the bonding relay lifts before the ground makes contact, and, voila, no GFCI trip.  Once the plug is fully inserted, the ground is once again safely connected.  The very short margin between the two lengths means that if I don't insert the plug far enough for the ground to make contact, then it will fall out altogether when I let go.

I only carry a "15-20 amp" version of this adapter, but it is made with 10-gauge (30-amp) wire.  I have found little need for a dedicated 30-amp (NEMA TT-30) version, but one could be made.  In the extremely rare case where I want to connect to a 30-amp GFCI, I simply use my TT-30P to 5-20R adapter at the pedestal, and the magic adapter at the end of the 10-gauge shore cord, and make the connection between the magic adapter and the 30/20 reducer last.  If I am at all worried about the intervening 20-amp rated plug and receptacle, I will dial the SW4024 input power down to 20 amps (normally on a 30-amp shore service we dial it down to 24 amps).

This is not for the faint of heart and there is a certain amount of risk if you do it incorrectly.  But realistically there is no other way to connect a properly wired SW-series inverter with the required external bond relay to a GFCI-protected shore service, short of using an isolation transformer.

-Sean
http://OurOdyssey.BlogSpot.com

[Madmike]

I will have to check as to what type of invertor I am using. As far as I can tell there is not transfer switch but I am new to this. I just plug it in and the 120volt stuff works, when the generator is running the 120v stuff works also. I don't switch anything. I pluged it in at my house using my 15amp adapter and it works fine as long as i am not on a GFI protected plug. This bus was done by a professional bus conversion shop and there has never been any problems with the electrical, it is the GFI's that it does not like. I will get it inspected either way.  When I get home tonight I will look it over and see if I can give you guys some part numbers.

[usbusin]

This is a problem I've had on a couple of occasions with my Trace inverter.  Why would a company such as Trace build a piece of equipment knowing it won't work when used in conjunction with a GFI?  Why should you have to "jerry-rig" something to "fool" it? 

Are all inverters like this or is it just Trace?

[Sean]

Gary,

The SW series inverters were never designed for RV use.  The RV listing (and software) was added as an afterthought.  This is why there is no internal bonding relay, and why no thought was given to cord-and-plug usage.

You take the bad with the good.  What makes these units so great is the load-support feature, which is a direct result of the grid-tie legacy.  No other RV inverter has this feature.

In later models, Trace made the ground wire for the filter capacitor a quick-disconnect affair for exactly this reason.  The bonding-relay related problems are external to the inverter, so Trace can hardly be blamed for that one (other than blaming them for not integrating the feature in the first place).

There really is no way around this without electronic control and sequencing of the ground bond.

-Sean
http://OurOdyssey.BlogSpot.com