Six-Disconnect Rule

[Jon Brogden]

Hello everyone,

Just a quick background. I am a student at the Milwaukee School of Engineering and am graduating in a few months as an Architectural Engineer with an electrical specialty. My question involves some practical insight on the six-disconnect rule. What are a couple reasons why a contractor or designer might want to use the rule and how does that impact project cost and safety. This question applies to the NEC 2017 interpretation of the code. Let me know if questions like these are not allowed in the forums. Thank you for the help!

 

[tthh]

The high level reason is that you don't want a situation where someone didn't turn off a breaker and got electroctured as a result. More things to shut off equals more chances not shutting off them all or the right one.

 

[hillbilly1]

The six switch rule allows larger 480 volt services without needing more expensive ground fault protection.

 

[augie47]

Primarily $$$$$
The cost of a main breaker especially, as hillbilly states, if you have to comply with 230.;95 for GF protection.

 

[norcal]

The six switch rule allows larger 480 volt services without needing more expensive ground fault protection.

Doesn't that go away with the 2020? Although the OP is asking in regards to the 2017.

 

[hillbilly1]

Doesn't that go away with the 2020? Although the OP is asking in regards to the 2017.

You still can with 2020, but each switch has to be in a separate enclosure, no more ILine panels and the like with two to six service disconnects.

 

[electrofelon]

You still can with 2020, but each switch has to be in a separate enclosure, no more ILine panels and the like with two to six service disconnects.

To clarify for the OP:. The 6 handle rule was most often applied to "MLO service panels" where you had 2-6 breakers for your service disconnects, instead of a single service disconnect. This worked very well where you had say 6 "sub panels" in a facility, so you could have one large MLO panel where each service disconnect would do double duty as a distribution breaker for a sub panel. For some perspective: a few years ago I got a 1000 amp Siemens P4, MLO with 6 200A service disconnects/breakers. It was about $4500. I also priced the same thing but with a 1000A main breaker and it was twice as much, $9000. You can still use the 6 handle rule in conjunction with 230.40 exception #2 and have 2-6 disconnects each in separate enclosures as hillbilly mentioned. The 2020 code change that eliminated the MLO option was one of the worst code changes IMO and was not justified with any valid reasoning.