This is vexing me and I hope experts can help me clarify.
Should I connect all my SPDs to the same ground busbar as all my other components or SPDs require a dedicated, exclusive ground busbar?
My research leads me to opposite conclusions. They both make convincing points. The one thing everyone agrees on is that all grounding points in a system must ultimately connect to a single grounding rod, something I was already assuming.
As further elaboration, I have a ground busbar connected directly to a ground rod. Then all my components and SPDs connect to this ground busbar. The question is whether I should separate out the SPDs and put them on a dedicated ground busbar, leading to the same ground rod. Electrically I don’t see any difference but I want to avoid the inconvenience if a dedicated ground busbar is not needed.
Fideri
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
2
Partly, this depends on what you are using them for and where they are located. I’m assuming you mean surge protection devices when you say SPD’s?
I can give you some examples of how I use such devices with my opinions on each use case and you and others can pick them apart:
Lightning protection with UNGROUNDED conductors. This would be for grounding the frames and racking for solar panels, for example. In this case, DC negative and positive aren’t usually grounded, but to keep static, nearby lightning, etc. from trying to find a path to ground through your equipment, an SPD would grounded with its own grounding electrode(s). If it’s a rooftop array, we add additional grounding electrode(s) and bond those electrodes to the earth safety ground of the electrical system of the building. The goal is to have a low impedance path for the static or surge to ground while keeping that ground and the electrical safety ground at the same potential by bonding them together.
For ground-mounted arrays, we use SPDs at the array and grounded to their own earthing conductor(s) and generally DO NOT bond these earthing conductors to the electrical safety ground in nearby buildings. If there was an extensive underground earthing network for other purposes then we likely would bond to this, but unless you’re running a small electrical sub-station, high-power RF transmitter, or telecom site, you aren’t likely to come across that.
Lightning protection for RF purposes. i.e. radio towers, antennas, etc. Similar to #1, but here we use inert gas lightning discharge devices. We want a low impedance path to ground, but low impedance to RF is different than low impedance to AC power. Lightning, however, is very wide band and nearly covers DC to daylight. My grounding conductors for this are 10cm wide pure copper strip from the lightning arrestors to a small network of grounding rods separated by 5m or so and all connected together underground with bare copper wire. I also bond this grounding network to the electrical safety ground to keep noise caused by ground loops from entering my radio shack.
Using SPDs on conductors already grounded elsewhere in your electrical system can use their own grounding electrode(s) but I would bond those electrodes to the primary earthing electrodes too to keep them at the same potential and not introduce ground loops.
There are other scenarios, but hopefully this helps you.
My scenario is #3. Everything seems to check out but I remain confused about one thing: Do I need a separate busbar for these SPDs (yes - I mean Surge Protective Devices) or I can use an existing shared ground busbar that has enough unused terminals?
I also have scenario #1 with rooftop panels, but those are taken care of according to your practice and the Victron docs. I was advised, as an addition, to bind #1 and #3 via an appropriate conductor to avoid the possible problem of different potentials.
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
4
I don’t know all the details of your site and installation so I can only generalize. I woulld suggest you install another grounding electrode into the earth to a separate bus bar and attach your SPD’s to this new bus bar. Outside, bond the two grounding electrodes to each other. If this is going to be a real pain in the butt then ground them to the existing grounding bus bar. Each of my scenarios above had ground rods local to the SPDs that were also bonded to electrical safety ground. In other words, bond the two ground systems together outside the house.