Supplementary Fuses and BCP

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C-Dog

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I am working on a project where a customer wants to power a small control panel from 120VAC receptacle. He is trying to have the panel UL508A certified.
5x20mm fuses (UL Listed as supplementary) are spec'd out in his design.
There are a couple relays and timers inside the panel with a pushbutton and selector switch on the door. Outputs are two solenoid valves.
Would branch circuit protection be required inside the panel before the supplementary glass fuse?
 
Makes sense, thanks for the reply.
I have a similar project for a UL508A panel with incoming supply of 208/120 three phase.
There is a three phase fused disconnect in the panel with Class J fuses (UL98). After the disconnect there are glass fuses (supplementary) feeding six different 120VAC circuits. Basically breaking up the 208V three phase into120VAC circuits. The devices they are feeding are external to the panel.(In a robot pod a few feet away) The devices are power supplies, a PC with Printer, Fanuc robot controller, and an outlet. Will the fused disconnect cover branch circuit protection or would each circuit need branch circuit protection on top of the supplementary fuses?
 
C-Dog said:
Makes sense, thanks for the reply.
I have a similar project for a UL508A panel with incoming supply of 208/120 three phase.
There is a three phase fused disconnect in the panel with Class J fuses (UL98). After the disconnect there are glass fuses (supplementary) feeding six different 120VAC circuits. Basically breaking up the 208V three phase into120VAC circuits. The devices they are feeding are external to the panel.(In a robot pod a few feet away) The devices are power supplies, a PC with Printer, Fanuc robot controller, and an outlet. Will the fused disconnect cover branch circuit protection or would each circuit need branch circuit protection on top of the supplementary fuses?
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Why not just use some single phase miniature circuit breakers instead of the glass fuses? It seems likely to me that you have created six branch circuits.
 
Why don't you use mninture DIN rail circuit breakers instead of fuses and make things better for the Electrical Tech guys?
I have zero use for fuses in control panels if there is any way whatsoever to avoid them. I am also no UL design expert.
Fuses cause untold grief if you do not have the necessary supply of what can amount to too many different kinds, sizes, and flavors. The last equipment quote that I received for condensate return gear, I asked the MFG to re-spec with breakers and they seemed ok with doing so.
 
My first thought was UL489 breakers but no room in the panel. Barely enough room for fused terminal blocks. Tried to get the customer to give me a little more room to achieve this but was not possible. They also wanted fuses and not circuit breakers and specified 5x20mm fuses. The panel will also be supplied with SJO cord for each circuit so that it is more of a plug and play vs. their techs having to wire anything up inside the panel.
 
Glass fuses may get you in trouble with SCCR because in a 208V system, they will be in the power circuit. I wouldn't use them, I would use Mini Circuit Breakers at least. You can get those rated for up to 18kA. If your 208V system is capable of more than that, you may have to go to Class CC fuses or something.
 
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