Generator feeder disconnect location

don_resqcapt19

Moderator
Staff member
Location
Illinois
I think more emphasis needs to be placed on the reasoning for the rule rather than beating up this generator disconnect "Within Sight" rule that keeps coming up time after time that will never seem to be resolved.

Long story short the only reason I can see for the "Within Sight" rule would be for an emergency situation, and even then if you didn't know where to look for it to begin with you'd have to run around the building to try and find it anyway.

Its not like a disconnect for a motor or something like that. "Within Sight of the Building" doesn't make it "Within Sight" of whatever your working on like a motor or air conditioning unit or the like.

If it is for Emergency Shutdown Purpose and the reasoning is to be able to find it quickly the rule should read "Within Sight of the Buildings Service Disconnecting Means".

So what is the reasoning behind having to be able to see the disconnect or even the Enclosure for the disconnect on a generator installation?
If its for servicing purposes, why doesn't the Lockout Capability of the Disconnecting means come into Play?

If its for convienience in case of an emergency, then why is it not "Within Sight of the Service Disconnecting Means" instead of the building in general?

JAP>
The current rule says that where the generator disconnect is being used as the building disconnect as required by 225.31, then the generator disconnect must be within sight of the building.
If you don't think that is correct, you have plenty of time to work up a "public input" (formerly known as a "proposal") for the 2020 code. They are due the first Friday of November, 2017.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Don,

You have to open the doors of an enclosure to access the disconnecting device on a NEMA 3R switchboard. The same is true for larger service-entrance-rated NEMA 3R transfer switches, the disconnect device is located behind latched cabinet doors. The only difference for the generator is that the enclosure is not dedicated solely to the disconnect device. The definition of within sight states that the specified equipment is to be visible. I would think that the general term "disconnecting means" would include the equipment enclosure as part of the equipment.
In the case of switchgear, I would agree that the switchgear enclosure is part of the equipment. Where the generator disconnect is inside the generator building or enclosure, I don't agree. The generator building or enclosure maybe within sight of the building, the the disconnect inside the building or enclosure is not.
 

RB1

Senior Member
Don,

We will have to agree to disagree. I can't see where opening the door to a generator enclosure is any different than opening the door to a switchboard enclosure. In fact, our standby generator generator at the office, and the service-entrance-rated transfer switch directly beside that generator, utilize the exact same types of latches and operations to access the operating handles of the disconnecting devices. From that location both sources of supply can be disconnected using basically the same procedure; by operating the latches and opening the enclosure door to access the breaker handle. Neither disconnect is within sight until you open the enclosure. I do understand however that many people share your view.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Don,

We will have to agree to disagree. I can't see where opening the door to a generator enclosure is any different than opening the door to a switchboard enclosure. In fact, our standby generator generator at the office, and the service-entrance-rated transfer switch directly beside that generator, utilize the exact same types of latches and operations to access the operating handles of the disconnecting devices. From that location both sources of supply can be disconnected using basically the same procedure; by operating the latches and opening the enclosure door to access the breaker handle. Neither disconnect is within sight until you open the enclosure. I do understand however that many people share your view.
Do you need a "tool" to operate the latches?
 

jap

Senior Member
The current rule says that where the generator disconnect is being used as the building disconnect as required by 225.31, then the generator disconnect must be within sight of the building.
If you don't think that is correct, you have plenty of time to work up a "public input" (formerly known as a "proposal") for the 2020 code. They are due the first Friday of November, 2017.
Not all Generators back up the entire building.

JAP>
 

jap

Senior Member
So if the generator is not used for backup for the entire building then it doesn't have to be within site?

Jap>
 

RB1

Senior Member
Don,

You don't need a tool to open the latches, but they are lockable.

On a side note: Have you seen the Cummins residential grade SE transfer switches? They require a screw driver to access the normal source circuit breaker! The units are Listed and identified as service equipment, including the requisite marking of the service disconnecting means.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Don,

You don't need a tool to open the latches, but they are lockable.

On a side note: Have you seen the Cummins residential grade SE transfer switches? They require a screw driver to access the normal source circuit breaker! The units are Listed and identified as service equipment, including the requisite marking of the service disconnecting means.
If the disconnect needs to be readily accessible, then that disconnect does not meet the 2014 code rule for a readily accessible disconnect. Nothing in the listing can change that.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
So if the generator is not used for backup for the entire building then it doesn't have to be within site?

Jap>
If the generator is remote from the building and the generator supplies the building, the feed from the generator must have a disconnect at or on the building, or the disconnect at the generator must be within sight from the generator.
 

RB1

Senior Member
In the applications I have seen 230.92 applied and the service disconnect within the transfer switch did not have to be readily accessible.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
In the applications I have seen 230.92 applied and the service disconnect within the transfer switch did not have to be readily accessible.
We are not going to agree on this one either...it gets a red tag from me. This is based on the fact that the device needs a tool and not a key to open it. The code treats tools and keys differently....I have no idea why as the practical effect is the same.
 

jwelectric

Senior Member
Location
North Carolina
Conductors from a generator supplying a building are feeders by definition. This brings Part II of 225 into the installation of a 702 generator.

225.31 mandates a disconnect

225.32 mandates that this disconnect be nearest the point of entry ? would a generator sitting 5 feet from the building be the nearest point of entry

225.36 mandates that the disconnect be suitable as service equipment ? is the switch on the generator listed as suitable as service equipment

702.12 mandates that the disconnect meet the requirements of 225.36

Nothing in Article 230 applies to any generator install as far as the conductors from the generator to the building as these are not service conductors
 

iwire

Moderator
Staff member
Location
Massachusetts
Don,

We will have to agree to disagree. I can't see where opening the door to a generator enclosure is any different than opening the door to a switchboard enclosure.
I will have to disagree.

The difference (IMO) is that a disconnecting means on the outside of the generator is easy to spot and easy for say first responders to find and use while a disconnect located inside the generator enclosure is not easy to find, you have to open multiple doors until you find it. Sometimes these require tools to open and some generator enclosures are small buildings.


 

jap

Senior Member
Might be worth asking the generator manufacturer if they could install the disconnecting means on the outside of the enclosure to begin with.

That way we wouldnt have to buy an expensive generator ( That already has a disconnecting means) and then have to turn right around and buy a second disconnecting means just to be able to keep it within sight of the building.

JAP>
 
Top