SPD on DC line but where?

[SolarMusher]

Hi,
I would need to protect a DC fridge that I had installed last year in a cabin 30 feet from the 48V system located in the main lodge. This wire length is all burried and I'm wondering what I could do to protect this fridge (and step down converter) from spike the best I can. Two years ago a strike hits that place and three roof mounted panels were lost in the story, fortunately SPD's did their jobs and the rest of the system was safe  .
What would be the better place to install a SPD115? Close to the step down converter in the cabin? On epanel bus bar? Both?
Thanks,
Erik

[Westbranch]

Erik, do you have a panel box or ?? just before the step down? I'd put it there assuming it is close to the fridge.

[SolarMusher]

Erik, do you have a panel box or ?? just before the step down? I'd put it there assuming it is close to the fridge.

Allo Eric,
No, no panel box close to the step down converter, just a square metal box but I could change it for a 4x4 plastic box or MNPV3 to mount and connect a spd115 to other wires just before the step down. I was also wondering if the other end that is connected to the batt pos bus (where the classic output is directly connected) is at risk too?

[Westbranch]

the MNPV3 would be a good option. 

About the + line at the battery, is there an SPD after the Epanel or ?? that you have at the CC? 

I would think that if it is there and it protected the system so far, it will work again.

I remember a comment by Ryan, I think,  that it is the AC side most at risk...


hth
Eric

[vtmaps]

What would be the better place to install a SPD115? Close to the step down converter in the cabin? On epanel bus bar? Both?

I like both     I think it's a good idea to put it where the ground wire has the shortest, most direct route to the ground rod.

--vtMaps

[SolarMusher]

the MNPV3 would be a good option. 

About the + line at the battery, is there an SPD after the Epanel or ?? that you have at the CC? 

I would think that if it is there and it protected the system so far, it will work again.

I remember a comment by Ryan, I think,  that it is the AC side most at risk...


hth
Eric

No SPD at this time on DC loads/batt side as they were inside the lodge. I've never had problem with inside DC loads so I only have AC in/AC out/PV in protected by SPD300 x3.
vt, this cabin panel (few lights only) was grounded to the system inside the lodge. I think that it would be better to ground this cabin panel directly to its own ground rod/plate and to install a small combiner/spd grounded to the cabin panel beside the DC fridge.
Erik

[zoneblue]

Well i guess you can only put a SPD where there is an earth connection available. And the DC side should only have a single earth, likely in the main disco, or via the ground fault detector in the classic maybe.

The theory is that the large 'capacitance' of the battery generally protects the battery buses. However im not totally convinced, after our recent hit. Of course iIt helps if you can do all the dc wiring so wire lengths are identical, real close together and even a half twist in the pair from time to time. Id even ponder grounded metal conduit, after seeing what i saw here recently.

Quality components all survived, what was pretty much a direct hit. It was cheap stuff that died, for instance a led voltmeter (yes, that was directly attached to the main battery bus, via a breaker.)

[niel]

this is a tad late on this thread, but it's good to protect both the dc and ac sides of things. i assume yours is an offgrid setup and the ac wiring is buried so protecting just the dc input side should do it. you can go extreme with protections everywhere if you wish too, but i'd key on at the pvs and at the combiner or cc input. the ac lines can pick up emp too, but yours are buried and less apt to be a problem. if the ac is connected to the grid as well then do protect it too as the utility lines would carry the emp to you.