Mike Dolt Enterprises
Mike Dolt Enterprises
User: jwoody, Location: Orange County, CA
Asked on: Tuesday, June 1, 2021 at 11:28 am EDT
Answered on: Thursday, June 20, 2024 at 11:26 am EDT
Question: I've been inspecting the field installations of energy storage systems (powerwalls) and I'm wondering if the feeders for the tesla gateways (ATS) need to be rated as tap feeders. There are double mechanical lugs in the gateway (ATS) for each phase fed from the incoming gateway feeders. If it is a double lug and if 2 sets of feeders are from them, each one feeding a separate bus, then shouldn't they be rated as tap feeders? I've done dozens of these inspections and not one of them is rated for tap feeders but I can't seem to understand how they are not considered tap feeders. Any feedback appreciated
Electrical Code Interpretation
According to the National Electrical Code (NEC) 2020, Article 225.31, a tap feeder is defined as "a branch circuit conductor that has overcurrent protection at only one end."Application to Tesla Gateways
In the case of Tesla gateways, the feeders connected to the double mechanical lugs are fed from the same source (the utility grid) and protected by overcurrent devices at both ends. Therefore, they do not meet the definition of a tap feeder.
Double Lug Connection
The double mechanical lugs in the gateway essentially provide a means of connecting two separate feeders, each feeding a different bus. However, this does not change the fact that each feeder is still protected at both ends and therefore not considered a tap feeder.
Reasons for Not Rating as Tap Feeders Overcurrent Protection at Both Ends
The feeders connected to the gateway are protected by overcurrent devices (breakers) at both the utility side and the gateway side. This ensures that the conductors are adequately protected against overloads and faults.
Independent Operation
Each bus fed by the feeders operates independently, meaning that a fault on one bus will not affect the operation of the other bus.*
No Splicing or Tapping
The feeders are not spliced or tapped, which would typically be required for a tap feeder.
Conclusion
Based on the interpretation of the NEC and the specific characteristics of the Tesla gateway, the feeders for the gateways should not be rated as tap feeders. They are protected at both ends, operate independently, and do not involve splicing or tapping. Flag for review