NEC article 800.90(2) among other things says:
Fused-type primary protectors shall consist of an arrester connected between each line conductor and ground, a fuse in series with each line conductor, and an appropriate mounting arrangement.
This sounds very descriptive of the typical 5-pin solid state fuses I use all the time. On my current install, the contractor is planning to use 3M STG-2000, Krone blocks with fuse inserts, as a primary protector. I don't have a copy of UL-497 to reference so was wondering if anyone can tell me if the Krone blocks and fuses are acceptable as primary protectors or not. I was told by a Siemans employee that the Krone blocks were acceptable as secondary protectors, but can't verify that.
Thank you,
V
Fused-type primary protectors shall consist of an arrester connected between each line conductor and ground, a fuse in series with each line conductor, and an appropriate mounting arrangement.
This sounds very descriptive of the typical 5-pin solid state fuses I use all the time. On my current install, the contractor is planning to use 3M STG-2000, Krone blocks with fuse inserts, as a primary protector. I don't have a copy of UL-497 to reference so was wondering if anyone can tell me if the Krone blocks and fuses are acceptable as primary protectors or not. I was told by a Siemans employee that the Krone blocks were acceptable as secondary protectors, but can't verify that.
Thank you,
V