Fusible disconnect after meter for Duke/Progress

[JimP]

I have a few questions about fusible disconnects, to go between Duke meter and Sol-Ark 15K.

First, while Lowes has this disconnect, it doesn't have 200A fuses that I can find.

https://www.lowes.com/pd/Siemens-200-Amp-2-Pole-Fusible-General-Safety-Switch-Disconnect/5013278421

Evidently I need class H 600V 200A fuses? are 250V/200A OK as well? Any good brand and source?

Second, if I use a 200A fuse before all my equipment, I am concerned that the fuse might blow before the 200A breakers in the Sol-Ark or load panels. Is that a real problem? Are the fuses slower than breakers?

Thanks

 

[Oldphile]

200 amp fuses seem to be in short supply now. My electrician installed 150 amp time delay fuses and left me with one spare fuse.

 

[PhilIA]

I haven't seen them at any of the box stores. Amazon, Bussman NON-200. The ones that arrived were white label, made in Mexico, not China like the ad shows.

 

[jonjon09]

Which fuses did you end up going with for that Siemens disconnect? I have the same one for my 18kpv

 

[Hedges]

You can compare trip curves of fuses and breakers.
I found they overlapped, unless I used 400A class T fuses and 200A breakers.
If you have 200A breaker, can you use non-fused disconnect?

You should never trip the 200A OCP, anyway. That would either be too many loads, or a dead short. If dead short, that's where I wanted fused to blow, to protect breaker (rated for something like 2 operations?) Moderate overload, I wanted breaker to trip.

Stick in whatever value fuse you can buy, and stay under that load for now. Save as spares in case you later blow a 200A fuse.

 

[JimP]

Which fuses did you end up going with for that Siemens disconnect? I have the same one for my 18kpv

Still trying to figure it out.

 

[jonjon09]

You can compare trip curves of fuses and breakers.
I found they overlapped, unless I used 400A class T fuses and 200A breakers.
If you have 200A breaker, can you use non-fused disconnect?

You should never trip the 200A OCP, anyway. That would either be too many loads, or a dead short. If dead short, that's where I wanted fused to blow, to protect breaker (rated for something like 2 operations?) Moderate overload, I wanted breaker to trip.

Stick in whatever value fuse you can buy, and stay under that load for now. Save as spares in case you later blow a 200A fuse.

I talked to Signature Solar months ago (before even receiving my 18kpv) asking about fused vs non-fused. They said fused is not a requirement from their standpoint but they listed fused on the diagrams due to most utility companies requiring it. And sure enough when I looked at the requirements for my utility, anything with PV connections required a "load break rated AC blade disconnect with a visible air gap".

 

[Hedges]

Input to inverter needs fuse or breaker. Could be built in I suppose, but would not want a loose wire to short and not be protected by OCP.
Seems good to have OCP built into something that won't later get disturbed for repairs.

visible blade disconnect does not mean fuse. Could be located after a breaker, as mine is. Mine happens to have a fuse (100A) because that's what was readily available. That was convenient when I later rewired it, not fed by 70A branch breaker but by 200A main breaker.

Since you have 200A breaker upstream, I think non-fused is fine if wiring supports 200A. Fused disconnect is also fine. Use whatever fuse you can get for now.

 

[jonjon09]

Input to inverter needs fuse or breaker. Could be built in I suppose, but would not want a loose wire to short and not be protected by OCP.
Seems good to have OCP built into something that won't later get disturbed for repairs.

visible blade disconnect does not mean fuse. Could be located after a breaker, as mine is. Mine happens to have a fuse (100A) because that's what was readily available. That was convenient when I later rewired it, not fed by 70A branch breaker but by 200A main breaker.

Since you have 200A breaker upstream, I think non-fused is fine if wiring supports 200A. Fused disconnect is also fine. Use whatever fuse you can get for now.

Noted. The 18kpv does have breakers built in. My 200 amp main panel breaker is after the inverter, not at the meter main. I assumed the "load break rated" part meant it had to be fused.
Thank you for your help.

 

[jonjon09]

Still trying to figure it out.

I got the bussman non-200 ones from Amazon and my electrician says that should work. Now just waiting for him to actually show up for the install.