Hello,
I currently work as a maintenance electrician in a newer factory in NY. I was hired as a maintenance electrician/mechanic. I have associates degrees in electrical construction as well as controls and 20 years experience in industrial maintenance ( mainly troubleshooting and machine repair). I was assigned the task of taking over equipment installs after the outside electrical contractor terminated their contract. I am a little rusty on proper power distribution codes. I need to hook up a machine that requires 208V 30 amp three phase power. The prior contractor started a circuit for equipment in this area of the plant. They came off the 208 bus with a 100 amp fused disconnect. This disconnect was labeled with the identification tags for three new machines ( FCT55 ,FCT57, FCT 72). From the bus they ran number 3 AWG THHN in EMT to a J -box, and then down to a wall mount fused service disconnect for machine FCT57. This wall mount disconnect is three phase 208v rated for 100 amps. So far so good, ( I think) To hook up the machine I ran 3/4 EMT from the wall mount disconnect, and pulled in 10AWG THHN from the load side of the disconnect to the machine. Here's where it gets tricky. I cannot find any 30 amp fuses with the physical size that will fit this disconnect. I believe this is because the manufacturer makes it so you can't install the incorrect fuse. My first thought was to replace the 100 amp wall mount disconnect with a 30 amp version. Two problems with this, the number 3 AWG is all ready ran in the pipe won't fit under the lugs on a 30 amp disconnect, and more importantly the replacement 30 amp disconnect would be covered by 100 amp fuses in the bus disconnect. To me this is no good because the replacement wall mount disconnect will be rated for 30 amps and protected by 100 amp fuses. Am I crazy or is there some code exemption for this? The machine, and the 10 AWG would be covered by the 30 amp fuses in the wall mount disconnect, and the 3 AWG would be protected by the 100 amp bus disconnect fuses, but the 30 amp rated disconnect would not be protected correctly. The only option I see is to find some kind of fuse adapters and possibly leave the 100 amp wall disconnect in place, and try to fit 30 amp fuses in it. Any Ideas?
I currently work as a maintenance electrician in a newer factory in NY. I was hired as a maintenance electrician/mechanic. I have associates degrees in electrical construction as well as controls and 20 years experience in industrial maintenance ( mainly troubleshooting and machine repair). I was assigned the task of taking over equipment installs after the outside electrical contractor terminated their contract. I am a little rusty on proper power distribution codes. I need to hook up a machine that requires 208V 30 amp three phase power. The prior contractor started a circuit for equipment in this area of the plant. They came off the 208 bus with a 100 amp fused disconnect. This disconnect was labeled with the identification tags for three new machines ( FCT55 ,FCT57, FCT 72). From the bus they ran number 3 AWG THHN in EMT to a J -box, and then down to a wall mount fused service disconnect for machine FCT57. This wall mount disconnect is three phase 208v rated for 100 amps. So far so good, ( I think) To hook up the machine I ran 3/4 EMT from the wall mount disconnect, and pulled in 10AWG THHN from the load side of the disconnect to the machine. Here's where it gets tricky. I cannot find any 30 amp fuses with the physical size that will fit this disconnect. I believe this is because the manufacturer makes it so you can't install the incorrect fuse. My first thought was to replace the 100 amp wall mount disconnect with a 30 amp version. Two problems with this, the number 3 AWG is all ready ran in the pipe won't fit under the lugs on a 30 amp disconnect, and more importantly the replacement 30 amp disconnect would be covered by 100 amp fuses in the bus disconnect. To me this is no good because the replacement wall mount disconnect will be rated for 30 amps and protected by 100 amp fuses. Am I crazy or is there some code exemption for this? The machine, and the 10 AWG would be covered by the 30 amp fuses in the wall mount disconnect, and the 3 AWG would be protected by the 100 amp bus disconnect fuses, but the 30 amp rated disconnect would not be protected correctly. The only option I see is to find some kind of fuse adapters and possibly leave the 100 amp wall disconnect in place, and try to fit 30 amp fuses in it. Any Ideas?
