fisherelectric
Senior Member
- Location
- Northern Va
A retiree up the street has a plastic forming machine, used to melt and then form plastic sheets into different shapes. It uses a series of heating coils which slide over the work surface. He called me saying it blows the internal 30 amp fuses when it's on more than 5 or six minutes. He said he usually only has the heaters on for 2 or 3 minutes at a time. It is fed at a 30 amp fuse block which feeds the control circuits and then to a contactor that turns on the elements. The contactor is wired with 12 gauge THHN and rated 60 amps.I put an amprobe on the coils and they pull 36 amps. I asked him about the machine he bought which has no rating plates and no manufacturers name. He said it was a one of a kind prototype. The heat coils are wired together and back to the contactor with hi-temp (100 degree C) wire Type SWEF-2, also 12 gauge. I could replace the fuse block with a 60 amp block and run #8 to the contactor fused at 40amps, but I'm nervous about the SWEF-2 #12 feeding the coils. I have never heard of this type wire and don't know about the ampacity. He's been using this machine for several years.
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