The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!


2017 NEC and Related
2017 NEC
Now Available!

Recent Posts
Parking lot pole light swap....
by gfretwell
10/24/16 08:46 PM
International Wire Colour Codes
by Tjia1981
10/23/16 12:08 PM
Son of Sparky
by HotLine1
10/20/16 07:43 PM
Speaking of Plugmold ...
by gfretwell
10/17/16 02:37 PM
Broken battery charger? Check for cobwebs!
by gfretwell
10/17/16 02:30 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 14
HotLine1 7
ghost307 7
renosteinke 6
Potseal 4
Who's Online
0 registered (), 260 Guests and 5 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#76221 - 01/06/01 08:09 PM Emergency Generators
WireStu Offline
Junior Member

Registered: 01/06/01
Posts: 4
Loc: Farmingdale, NY 11735
Our job includes installing an 2 outdoor 250 kW 3 phase 4 wire 480 Volt enclosed generators.
One site has a 600 Amp 3 phase 4 wire main breaker supplying the normal side of a 600 Amp 3 Pole Automatic Transfer. The main breaker and ATS are in the same room. The generator has a 600 Amp breaker mounted on the generator (capable of being locked open)inside the generator enclosure. The generator is about 100' from the building. The neutral in the generator is isolated from the frame. We are running 4 wires + gnd. into the building. My question is does the since I believe the NEC does not consider this a separately derived service (3 pole ATS) are the generator feeder cables considered a service entrance and thus require to have a disconnecting means where the cables enter the main building. The system neutral and the generator neutral are connected together on an isolated bus section in the ATS.

The other site is similar except the is a 4 pole transfer switch. Since this is considered a separately derived service does this installation require a disconnect switch inside the main building on the generator cables before they terminate in the ATS.

Thanks in advance for your help.


2014 / 2011 NEC & Related Books and Study Guides
#76222 - 01/07/01 01:16 PM Re: Emergency Generators
resqcapt19 Offline

Registered: 11/10/00
Posts: 2209
Loc: IL
The generator conductors are, as you stated, feeder conductors and therefore no "service" disconnect would be required. It is, however, my opinion that Article 225 will require you to provide a disconnect for the generator conductors at the building.

#76223 - 01/08/01 03:46 AM Re: Emergency Generators
sparky Offline

Registered: 10/18/00
Posts: 5545
Do both sites have an ATS ? Do both sites have utility power?

#76224 - 01/08/01 06:28 PM Re: Emergency Generators
WireStu Offline
Junior Member

Registered: 01/06/01
Posts: 4
Loc: Farmingdale, NY 11735
Yes both sites do have utility power and ATS's.


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals