DC-GFP breaker needed with a Classic 150?

[firerescue712]

I have a MNDC-GFP63 Breaker between the Classic 150 and the MNPV6 Combiner.  Is the breaker necessary?  Does the Classic 150 meet the NEC requirements for an inline DC-GFP?  I have a non-Classic MPPT CC the breaker could be used on if not needed with the Classic 150.

[Halfcrazy]

The Classic has built in Ground Fault protection so an External device is not needed.

Ryan

[firerescue712]

Thank you, Ryan.  I did not realize this when i ordered the Classic 150.  I guess too much protection is better than none at all.  Now to swap the breaker to the "other" cc.

Have a nice day.

I am still anxiously awaiting info on the stackable inverters ya'll are working on.  I am needing to upgrade to a PSW, but want it stackble and small. 

[vtmaps]

Using two GFP devices on the same system can be problematic.  Actually, even having just one DC-GFP is a problem.  Its not Midnite's fault that their GFP system is dangerous and may cause more problems than it solves.   The problem is that the dangerous system they (and everyone else) use is required by National Electric Code.

Read more: http://midnitesolar.com/smf_forum/index.php?topic=142.0

One of the many problems with the DC-GFP is that if you have more than one in a system the fault current may split between the various DC-GFPs and fail to trigger them.

I read in another thread here (can't find it now) that Midnite has an elegant solution to this one small part of the problem.  If you have multiple classics you use the GFP in one of them and turn it off in the others.  If the GFP trips, it will shut down all the classics.

--vtMaps

[firerescue712]

I thought this might cause a problem.  I will take out the GFP breaker this evening and replace it with a MNEPV63 breaker.

[vtmaps]

I thought this might cause a problem.  I will take out the GFP breaker this evening and replace it with a MNEPV63 breaker.

I believe that breaker is polarized.  Do you know which way to wire it?  --vtMaps

[firerescue712]

Yes,  I was using it before the Ground Fault breaker arrived.  Thank you for checking.  It is better to be safe than to be sorry.

[Robin]

DC-GFP breakers can be a problem. When there is a ground fault, the DC-GFP opens up the high current path to stop current flow, but it also opens the grounded conductor. When the NEC made this requirement about 15 years ago, there was no such thing as a system over 48 volts. We did not have 600V grid tie inverters back then. If a DC-GFP is tripped and you are on the ground and you touch the PV negative (grounded conductor) you may just be electrocuted! We actually do have a solution for this now. We have a 100 amp, shunt trip 2 pole breaker with a 1 amp sense breaker. How this fixes things is that it breaks the positive and negative conductors. That eliminates any shock hazard. All of the systems mentioned here including the one built into the Classic meet code. I am not a fan of any DC-GFP! They were originally required by the NEC to stop fires. Ground faults never start fires unless it results in arcing and sparking. Since arc fault detectors are now required and they do actually stop fires, I do not see why we still need DC-GFP's. They will never get rid of the requirement though. Grid tie inverters will be required to be ungrounded in the future. That also solves the problem.