I am currently installing a split phase EG4 system in my home, much like the one in the latest Will Prowse video. In his video, he showed how to wire the inverters to a subpanel which was N/G bonded. He recommenced everyone off grid follow his wiring. That is great in all, however 95% of people in an off grid situation would like to use their main or a sub panel which is already existing, because it already has all your loads in the panel. Existing panels are not N/G bonded, correct? The Ground and Neutral are separated, the ground never carries current except in a short. So my question is simple, is it a problem if you wire these inverters to a main or sub panel with the ground connected to earth and the neutral on the neutral bar? Again this is not a UPS, it is strictly off grid. When the power goes out, I throw my main disconnect which isolates me from the grid and I turn on my EG4 split phase system.
EG4 6500EX off grid install with no Neutral Ground bond.
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timselectric
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Your main panel should already have a N/G, if it was installed correctly.
timselectric
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If one of the hot legs shorts to ground.
The only way that the breaker or fuse can open the circuit is if there's a N/G bond.
The only way that the breaker or fuse can open the circuit is if there's a N/G bond.
So when installing these inverters, it is ok to install the double ganged inverter out put breaker on my main panel and connect the neutral to the neutral bar and the ground to the ground bar? Or do I have to connect the ground and neutral from both inverters together in the main panel?
BentleyJ
Solar Wizard
I know this question is going astray from the post. Have to ask. Not sure I understand the above statement. If a hot leg touches a grounded surface excess current will flow to the ground rod and trip the breaker regardless of the N/G bond and the circuit will be open. Hope is not to dumb of a question. What am I missing?
timselectric
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Actually it won't. It's not a short, unless it returns to the source. Without the N/G bond, it's just going to make everything that is connected to ground, hot.
timselectric
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Both neutrals and grounds need to go to the panel.
timselectric
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The purpose of the grounding system is to provide a low resistance path for fault current, back to the source. Through the N/G bond.
BentleyJ
Solar Wizard
Ya, I sketched it out. The N/G bond allows utility power to flow back to the neighborhood transformer which is the source. I was thinking that the transformer neutral was grounded at the transformer, guess it isn't.
Of course then I was unsure as to why the actual ground rod is necessary but that is for lightening.
timselectric
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The misconception is that the ground rod ties your system to earth.
But it's actually the other way around. It ties the earth to your system.
It's confusing because we also call the dirt, ground.
As in, "I fell on the ground".
But it's actually the other way around. It ties the earth to your system.
It's confusing because we also call the dirt, ground.
As in, "I fell on the ground".
The N-G Bond needs to be at the source before your RCD/GFI
A ground fault will allow current to run through the ground wire as well as Neutral, and the RCD/GFI will see a difference between Line and Neutral currents and trip.
Trouble comes when you have 2 potential sources. You use the Utility N-G link for utility supply, and need to switch in a N-G bond at your inverter when on Island mode. Some Inverters do this automatically, some have an output you can use to switch a relay, and some have nothing
A ground fault will allow current to run through the ground wire as well as Neutral, and the RCD/GFI will see a difference between Line and Neutral currents and trip.
Trouble comes when you have 2 potential sources. You use the Utility N-G link for utility supply, and need to switch in a N-G bond at your inverter when on Island mode. Some Inverters do this automatically, some have an output you can use to switch a relay, and some have nothing
You should take a look at Filterguy's excellent resource on the subject: https://diysolarforum.com/resources/grounding-and-bonding-for-mpp-lv6548-and-eg4-6500ex-48.275/
Zwy
Solar Wizard
Strictly off grid, the N-G bond should be in the inverter which is source.
There is not any reason to do it different.
However, you do have a grid supply. Unless you install a 3 pole transfer switch before the main panel where neutral is switched, then it isn't truly off grid. Turning off the main breaker is not the same thing. With the 3 pole transfer switch, the system is considered separately derived, while turning off the main breaker is considered non separately derived.
Quattrohead
Solar Wizard
Quattrohead
Solar Wizard
A main panel has the N/G bonded together, any subsiquent sub panel does not and must be fed with L1, L2, N and G wires.
In your senerio, if the sub panel is going to be your main panel being fed from your inverters with no grid ever again, then N/G need to be bonded in the panel and a local ground rod used.
timselectric
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N/G bonding is required to be at/or before the first means of disconnect. (Wherever that is, depending on each individual system) After the first means of disconnect, neutral must be isolated from ground.
Quattrohead
Solar Wizard
Details matter !!!! I have an outside meter/service panel that only the AC compressor is connected to, then a run into the house for the "main panel"
Is it strictly a main panel anymore ??? Where is my N/G bond ? I will have a look when I feel like it
timselectric
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Outside panel is the main panel. And the N/G bond should be located there. The inside panel is a sub panel.Details matter !!!! I have an outside meter/service panel that only the AC compressor is connected to, then a run into the house for the "main panel"
Is it strictly a main panel anymore ??? Where is my N/G bond ? I will have a look when I feel like it
Zwy
Solar Wizard
Better go check out the Mike Holt videos.
