What is the proper way to connect the positive wire from the surge protector to the positive side of the circuit in a MNPV3, MNPV6, or MNEDC125 box. There are no positive bussbars in these to make that connection.
One common method of connecting an SPD to the positive, or line circuit, is to add a breaker, and connect the hot SPD wire to this breaker, if there is a spare breaker position available. The SPD wire will be the only connection to the added breaker.
Some of the recent Combiners may have an extra hole in the positive busbar, for an added machine screw/nut in the buss. A ring terminal could be crimped onto the SPD's hot wire, and this terminal connected to the screw that was added.
IMO, Vic
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If the SPD was connected to a breaker 1st, then if that breaker was off somehow, then I guess the SPD could not do its job!
I would rather put the SPD inside near the controller in the MNEDC175. Does it matter what side of the controller it is put, input or output?. If its on the input, then what is the proper way to connect the SPD without a positive busbar?
Quote from: labusker on October 10, 2019, 11:12:28 AM
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If the SPD was connected to a breaker 1st, then if that breaker was off somehow, then I guess the SPD could not do its job!
I would rather put the SPD inside near the controller in the MNEDC175. Does it matter what side of the controller it is put, input or output?. If its on the input, then what is the proper way to connect the SPD without a positive busbar?
Me - I would just put it in the terminal with the larger wire and they will be tightened together and the electrons won't care .
Larry
Hi lab..,
The SPD for the PVs needs to be as close to the PVs, as it can be. At the PV Combiner is the best place for it.
The standard practice, is to use a MNEPV breaker inside the Combiner (or, for an AC panel, a breaker is often used, and is Code IMO).
There should be no reason, whatsoever, that an MNEPV breaker would switch itself off. Even seems unlikely that in the event of a close-by lightning strike, that this breaker would trip. The SPDs have an internal fuse, to protect it from MOVs shorting, from a large surge event.
Believe that using a screw and crimp terminal for the connection to the bussbar in the Combiner, should pass inspection.
Most wire connection terminals are not rated for multiple wire/cable connections. Would probably work fine in most situations, but, believe that this is not Code compliant -- considered unreliable.
Opinions from someone who is NOT a Code wizard. Vic
Quote from: labusker on October 10, 2019, 11:12:28 AM
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There may be a way, but do not see it. FWIW, Vic
if a SPD is wired through a breaker and that breaker is off due to being tripped, during maintenance, etc., then I would think the SPD would not function properly. Your thoughts.
Quote from: labusker on February 01, 2020, 05:41:57 AM
if a SPD is wired through a breaker and that breaker is off due to being tripped, during maintenance, etc., then I would think the SPD would not function properly. Your thoughts.
Could then use a fuse holder..maintenace shouldn't interfer then...
It all depends on what you intend the SPD to protect, and you wire it to the side of the breaker that wants protection.
Can a classic 150 be protected if the surge protector is wired on the positive side of a breaker with the classic on the negative while the breaker is tripped? I am wiring the protector in the MNDC125 and to put it on the classic side of the breaker requires using a wire nut on my 8 awg wire. Is a wire nut good enough?
I would NEVER use wire nuts in a solar or battery application. There is a lot of long, continuous amps, much more so than household appliances that are off more than they are on, solar is on for 4 hours at full power and who ever oversizes the wires !!
Quote from: mike90045 on February 05, 2020, 06:28:28 PM
I would NEVER use wire nuts in a solar or battery application. There is a lot of long, continuous amps, much more so than household appliances that are off more than they are on, solar is on for 4 hours at full power and who ever oversizes the wires !!
Two issues aren't there ? A good non oxidizing connection especially for low voltage . But then there is the physical connection that a wire nut makes and it's heat rating. I have watched some video's where people put all types of various connectors on wires and seriously overloaded them. Wire nuts did not fail even after the plastic on them melted off and that took extreme overloading. But I have seen where a wire nut melted in 120v AC - but the wires were never twisted tight in it so that is why it got hot.
Larry