Hi AC Power guru’s…..
I know this topic has been done to death, and I have been reading posts till my eyes are bleeding… But I can’t find a definitive answer to my specific question. Most posts relate to boating with shore power anomaly’s, RV Vans with their chassis dilemmas or complicated multi-phase setups with GFCI issues….
There appears to be conflicting opinions on this diverse topic, so here is my question to make my newly installed off-grid back-up circuits safe and get my head around Earth / Neutral bonding once and for all !
From looking at the attached pics and sexy diagram, this is how my newly installed and fully compliant system is right now, prior to the connection of any domestic mains supply or AC generator input. Due to my very limited solar array and allusive Winter sunshine here in the Mountains of South Eastern Australia…. I’m wanting to supplement this stand-alone system with some power from my existing domestic supply to charge my battery’s when they are critically low. This new stand-alone system supply’s my fridge, two water pumps and my home lighting only. (see below for system specs)
My questions are as follows:
1. Should the Earth/Neutral bond strap in DB-2 Sub Board (see pic #3) be connected at all ? Or should the E/N bond be controlled by, and within the Quattro only ?
2. When my domestic supply power (DB-1 Main Board) is connected to the Quattro (AC in 2), should the loads on DB-2 Sub Board obtain their E/N bond from the power source (i.e. DB-1 Main Board) and NOT locally from DB-1 Sub Board via it’s E/N bond strap ? (assuming the Quattro’s Earth Relay opens as it should whilst it is connected to AC power on it’s AC input, and it’s own E/N bond is disconnected also)
3. Should I include the Earth wire at all from my domestic supply (DB-1 main Board) when supplying the Quattro with power (AC-in 2) due to the fact that both DB-1 Main Board and DB-2 Sub Board both have separate Earthing Rods (approx. 15 metres apart) ? (my instincts say ‘absolutely YES’ but I need this confirmed)
4. Should the earth wire on the output of the Generator be connected to the Quattro AC-in 1 also ? Or left as it is now with it’s output Earth and Neutral and Active connected to DB-2 Sub Board first (via circuit breaker) and then only Active & Neutral cables going into Quattro AC-in 1 ? (see pic #2) i.e. When system is running on Generator AC, shouldn’t the Power Source (Generator) dictate the E/N bond and NOT the DB-2 Sub Board ? (assuming again the Quattro’s Earth Relay opens between it’s Earth & Neutral whilst the Generator AC is present on AC in 1) and (assuming the Generator does in fact have it’s own internal earth neutral bond)
5. Finally, from looking at my beautiful diagram, where would you expect to see RCB units installed ? At present, the only RCB’s within DB-2 Sub Board are on the output loads.
Much thanks in anticipation of any light you could shed on this, and avoid my sleepless nights laying awake pondering earths, neutrals and electrified things…..
System Specs: (see pic #1)
Quattro II 230v 48v/5K/70
2.64kW PV 3S2P
2x BSL LiFePo4 48v Connected via CAN-Bus)
Cerbo GX
Victron MPPT 150/60 (connected via V.E Direct)
