Overcurrent protection for "service receptacles" on industrial control panels

[Peakhunter]

When adding a "service receptacle" to an industrial control panel, is it acceptable to undersize the overcurrent protection (say 3-5 amps fuse) since the receptacle is only likely to be used for a laptop? What codes apply to the application of receptacles to industrial control panels.

The implication is significant because transformers in the panels get big and hot so keeping loads small is significant.

 

[tom baker]

Thats mostly a UL508 control panel listing issue. We used a nice hubble din rail mount GFCI recptl, fused at 5 amps.

 

[MD Automation]

Agree 100% with Tom – very common in some of our Control cabinets we have designed over the years to have them either fused or controlled by miniature (DIN rail) breakers in that 5A range. Like you mentioned, we used them for laptop chargers during development and deployment. Also, years ago it was common to use consumer type Ethernet switches that needed power from a wall wart xfmr. So we had outlets for those, always protected quite low in terms of current draw.

Now we use more industrial Ethernet switches, powered by 24 VDC. But we still have many cabinets designed with a utility outlet, but never protected by a 15 or 20A overcurrent device.

 

[tom baker]

Our receptacles are feed thru with an outlet on the door, Graceport makes a nice unit. We also had an ethernet port but later on in the project, I would disconnect the enet cable due to cybersecurity issues, these were in unmanned and unalarmed buildings