EG4 Official Neutral Ground Bond Thread.

[FilterGuy]

I don't think I'd actually want it to be fully automatic on shore power input though - As others have pointed out in this thread, if you plug into shore you want to disconnect your bond, but if you plug a generator into the same AC input you'd actually want to keep it bonded.

Generators come in two flavors: Bonded and Not-Bonded. Generators that come with a bond can usually be modified to remove the bond.

How the generator gets tied into the system is critical. If the relay circuit above is used and a non-bonded generator is tied to the gen port of a common neutral inverter everything will work properly.



However, if the generator is going to plug into the Shore power plug, the generator should be bonded (It should mimic shore power). It is typically pretty easy to add a bond to an unbonded generator.

Although I see what you're suggesting actually in the second picture, this would require having separate inputs for gen/shore which I wasn't planning on.

Typically, if there is a shore/generator Auto Transfer switch I would expect the generator to be permanently wired (or at least permanently plugged in) As long as the generator has a permanent connection and it has an N-G bond, a 3-pole transfer switch can do the dynamic bonding for the RV.

Does someone sell a bonding relay box like this, or is this a proposed circuit to make?

It is a proposed circuit that has not been built. However, I did help a guy build something very similar for a 120V inverter and it worked well.

Note that the links in the pic above take you to the parts on Amazon. Also, note that the terminal blocks are the most expensive component. You could build it for less by using a different wire connection method. Just make sure the connections are solid and can't vibrate loose.

• Don't use wire nuts
• If you use WAGO connectors, put tape over the levers so they can't accidentally pop open.
• Crimped connectors are best for mobile applications that will vibrate and bounce

 

[gribov42]

@FilterGuy thanks for the tips! I'd like to have 1 input to be used mainly for shore, but occasionally for a generator (not hard-wired). I think I'll go with something like this, and just make an adapter for adding a bond to the generator (or maybe an "override switch" which adds the bond using a switch I have hidden away in my electrical panel) since that will be a rare use-case, but nevertheless one that will happen. If I go with making the override switch I don't think there's any problem with just using a standard switch.

As for your wire-nuts suggestion, I'm curious what you recommend - The taped off WAGO or something better? I'm using marine-grade stranded wire for all my AC-side, and prefer something that would work well without needing to crimp every connection.

 

[gribov42]

That being said, I'm still trying to decide between the EG4 and a Victron setup, and leaning towards Victron currently, though it seems the Multi-plus-ii handles the relay circuitry internally.

 

[FilterGuy]

As for your wire-nuts suggestion, I'm curious what you recommend - The taped off WAGO or something better? I'm using marine-grade stranded wire for all my AC-side, and prefer something that would work well without needing to crimp every connection.

There are many options.

In all options, be sure to tie the wires down so they don't bounce around a lot. This is true for the whole length of the wire, but it is particularly important at the ends where connections are made.

I have seen people use wire nuts, but I would not use them. (Have you ever noticed there are no wire nuts in cars?)

Wago connectors with tape around them is probably the cheapest. Just make sure they are not bouncing around.
In my design above I call out the DIN Mount Connectors, but that can get expensive.
https://www.amazon.com/Assembly-Kit-DK6N-Black-Gang/dp/B0BDGML77P/

Search for terminal blocks in Amazon and see if anything catches your fancy.

 

[gribov42]

Thanks! I think I'll spring for DIN connectors like this in my electrical closet where all the gear is mounted, and get an assortment of Wago's for various splices across the bus.