How to comply with NEC 240.67 Arc Energy Reduction in 2020

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pv_n00b

Senior Member
Location
CA, USA
I'm looking at the 2017 NEC 240.67 and trying to figure out what is available to satisfy this requirement along with the other requirements for PV systems. Currently there is no fused disconnect switch that can do this and has a visible blade disconnect. It will soon be 2020, any ideas? This is going to put a real crimp in PV system interconnections over 800kW.

I'm thinking maybe an "electronic" fuse that will replace the standard fuse in a bladed disconnect but so far I have not found anything.
 

pv_n00b

Senior Member
Location
CA, USA
Possible, but a lot of assembly required unless someone is selling an integrated unit. The GE HPC is a contender except no visible blades. This is the reason 240.67 has delayed implementation, the CMP involved was hoping there would be products on the market that would provide this functionality by 2020. So far I'm not seeing anything ready to go. Sure we could cobble something together out of parts but that was never the intent.
 

Mer2112

New User
Location
Illinois
Occupation
Senior Technical and Quality Manager
Something to remember, as long as the fuse opens within 70 ms at the available arcing current, no additional means are necessary. There are many different brands and models of Class L fuses, all with different clearing times. Once you know the available arcing current, take a look at the different Class L fuses out there and choose one that will open within the 70 ms time. With Class L fuses, you can also downsize the fuse without any modifications to the switch itself. No fuse adaptors are needed. Just because you have a 2000 amp swtich, it doesn't mean you have to install 2000 amp fuses. Here's a great article from Mersen duscussing that topic: https://ep-us.mersen.com/sites/mersen_us/files/2018-11/TS-Reducing-Fuse-Amp-Rating.pdf
 
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