Just looking for some clarification. I was looking at project in CT and there were 2 components that were supposed to have 277 volt to 24 volt DC power supply. when the equipment arrived the power supply voltages for one unit was 120 volt and the other was 120 to 240 volt feed. Due to time constraints the contractor added a 277/120 volt 50 VA transformer which is feed from a 20 amp 277 volt breaker. From the secondary side they ran to a duplex receptacle (to be changed to a single receptacle per the engineer) to plug a small transformer to provide 110 volts to a fiber switch and then just tapped off the secondary to feed the other power supply with 120 volt. This equipment is all in NEMA 3 R enclosures outdoors. The transformer and receptacle were field installed and is in the same enclosure. This is not UL listed control panel.
the comments in red below are from the electrical engineer.
1. Back panel required to prevent penetrations through a NEMA rated
enclosure
2. Change the duplex receptacle to a single receptacle
3. Add label to receptacle "120VAC Instrument Power Only"
4. 10VA load for the Fiber Converter
5. 71VA load for Green Power Monitor (Load based upon max loads identified
on the cutsheet)
6. Transformer probably should be 100 VA for loads.
Here are my questions:
Since the duplex receptacle is going to be changed to a single receptacle and is located outdoors but in a NEMA 3 R enclosure does it need to be ground fault protected?
How does adding a label note 3 above offer protection from the transformer being damaged if someone should plug a piece of equipment into the receptacle?
Shouldn't the receptacle be required to be protected by the size of the receptacle 15 or 20 amp?
the comments in red below are from the electrical engineer.
1. Back panel required to prevent penetrations through a NEMA rated
enclosure
2. Change the duplex receptacle to a single receptacle
3. Add label to receptacle "120VAC Instrument Power Only"
4. 10VA load for the Fiber Converter
5. 71VA load for Green Power Monitor (Load based upon max loads identified
on the cutsheet)
6. Transformer probably should be 100 VA for loads.
Here are my questions:
Since the duplex receptacle is going to be changed to a single receptacle and is located outdoors but in a NEMA 3 R enclosure does it need to be ground fault protected?
How does adding a label note 3 above offer protection from the transformer being damaged if someone should plug a piece of equipment into the receptacle?
Shouldn't the receptacle be required to be protected by the size of the receptacle 15 or 20 amp?
