Mike Dolt Enterprises
Mike Dolt Enterprises
User: LukeMac, Location: Tennessee
Asked on: Sunday, March 27, 2011 at 5:05 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:21 am EDT
Question: I am bidding a set of plans that show the main electrical panel at a detached garage and guest house. This building is closest to utility pole.The main house is quite large, it requires more than a 200 amp sub panel.Typical equipment: Siemens 400 amp meter panel which has one 200 amp breaker with 30 spaces, and a 200 amp breaker for a sub panel.As far as I am aware, all feeders to the main house have to be in the same conduit; I cannot run a 200 amp underground feed, and then also a 100 amp underground feed.Should I install a 400 amp meter at garage, then a 400 amp disconnect at the main house with (2) sub panels, and then backfeed the garage with a 100 amp sub panel?Has anyone had experience with the meter main being installed at a smaller outbuilding?Thanks
Yes, it is possible to have the meter main installed at a detached garage or outbuilding.Steps
1.
Install a 400 Amp Meter at the Garage
Install a Siemens 400 amp meter panel with one 200 amp breaker for the main house and one 200 amp breaker for the garage/guest house.2.
Run a 400 Amp Underground Feeder to the Main House
Install a single 400 amp underground conduit from the garage to the main house.3.
Install a 400 Amp Disconnect at the Main House
Install a 400 amp disconnect switch at the main house.4.
Connect the Underground Feeder to the Disconnect
Terminate the 400 amp underground feeder at the 400 amp disconnect switch.5.
Install Subpanels at the Main House
From the 400 amp disconnect, install two subpanels: a 200 amp subpanel for the main house and a 100 amp subpanel for backfeeding the garage/guest house.6.
Backfeed the Garage/Guest House with a 100 Amp Subpanel
From the 100 amp subpanel at the main house, install a 100 amp underground feeder back to the garage/guest house.
Benefits of this Approach
Simplifies Conduit Installation
By running a single 400 amp conduit from the garage to the main house, you can avoid the need for multiple conduits, which can save time and labor costs.
Provides Future Expansion Capability
The 400 amp disconnect switch at the main house provides ample capacity for future expansion of the main house or the garage/guest house.
Complies with Code Requirements
This approach meets the National Electrical Code (NEC) requirements, which prohibit separate feeders for a single service panel from being installed in different conduits.
Considerations
Distance Between Buildings
The distance between the garage and the main house will affect the cost and complexity of the installation.
Trenching and Conduit Installation
Trenching and conduit installation can be time-consuming and labor-intensive, especially if the buildings are far apart.
Meter Accessibility: The meter should be easily accessible for inspection and maintenance. Flag for review