I'm looking for opinions on whether or not the rule of 6 applies to a situation I have. It is an Industrial facility where the utility is supplying 12.47KV. The line of demarcation is at a switchyard where, after the metering, it then feeds an isolation switch on the company side of the line of demarcation, with kirk key interlock to a main breaker located in company-owned 15 kV switchgear. There is one service, meaning one set of service conductors, leading from the isolation switch to the switchgear lineup that, as I said, first lands on the MCB at th 15 kV switchgear, which then supplies power to adjacent switchgear sections containing breakers that serve various buildings on the site. Does NEC 230.71 now limit the number of feeder breakers in this arrangement to 6? My take is that there is only one service in play and the MCB is a single point of service disconnect with the downstream breakers being feeder breakers, and the number of feeder breakers isn't limited to six by NEC 230. I am getting challenged on this by other engineers involved in the project.
Rule of Six question
- Thread starter WetWilly
- Start date
- Status
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Feeder breakers do not and have not been subject to the six switch rule for services
Thank you for the confirmation. May I bother you for another, related, opinion? In Article 225 "Buildings or Other Structures Supplied By a Feeder or Branch Circuits", 225.33 uses the same language as for a service but refers to it as a "supply" when discussing the disconnecting means. Interestingly, the 2020 NEC did not make the same changes to 225.33 as it did in 230.71 for services. That said, when supplying a separate building or other structure (outside gear lineup - perhaps?) it continues to allow up to but not exceeding 6 disconnecting devices "in a single enclosure or a group of separate enclosures, or in or on a switchboard or switchgear". So it does seem to leave open the landing of a feeder supply on a MLO piece of gear, in a separate building or structure, but limits the number of supply disconnects to 6 or less. Would you agree? Thank you.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Yes, in a detached building, the six-throws-of-the-hand rule does apply, just like a service, because "a" main disconnect is required.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
I stand corrected!
jtinge
Senior Member
- Location
- Hampton, VA
- Occupation
- Sr. Elec. Engr
I generated a document comparing NEC requirements for Services to those for Supplies. If interested, PM me and I can email to you.
- Location
- Illinois
- Occupation
- retired electrician
We have rules that permit up to six means of disconnect for a building...six means of disconnect = the rule of six
Thank you Sir Don!
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Kind of means when disconnecting a building, possibly in an emergency situation, they don't want you to have to throw say 50 switches, they want it to be six or less, and the six that are allowed must be grouped in same location as well. There are times when there might be other disconnects, with conditions though.
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