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Square D I-Line Combo Panelboard Application

by Rick A. Chapman, REVCO Senior Technical Specialist 

In the Metro New York area, there are many occasions where the residential or commercial electrical distribution equipment requires a larger amperage system than the norm.  This is particularly true on the East End of Long Island where the region calls for much larger panels (400/600/800-amps or more) due to the size of the homes and businesses.   REVCO Lighting + Electrical Supply, based in Southampton, NY with five locations, was the first distributor in the United States to offer the new Square D I-Line Combo Panelboard (combining the I-Line and NQ/NF sections into one panelboard) for a Southampton residential project that required high amperage service to be housed in a small mechanical room (See Figure 4).  The Square D I-Line Combo Panelboard was the best solution for this home.  It features smart, space-saving design for fast installation and a smaller footprint. 

Today, electrical contractors' have a number of options in order to accommodate this type of project, which includes (1) using multiple load centers in parallel service, (2) using a commercial distribution center or (3) a combination of both.  In smaller homes and businesses, electrical services typically use 100/150/200 or 320-amp service where the branch circuit does not exceed 125-amps.  In the larger homes and businesses, a much larger electrical panel is required that holds numerous large breakers in order to provide enough amperage.  The challenge arises for the home that requires high amperage service and a small mechanical room, which is becoming a challenge and norm for electrical contractors.   

Figure 1 (below) shows the typical method used by a number of electrical contractors, today:

Figure 1 

This above example demonstrates the main distribution panel with an 800-amp main, several 150/200-amp breakers and two panels for standard branch circuits.  While it might be a good solution for the home, (one with an exterior garage, pool house, expanded landscape lighting, etc.), there are several issues with this type of design:

1.  Figure 1 requires using two 200-amp distribution breakers to feed panels that are literally inches away.
2.  There is too much wasted space with this type of design.  Today, mechanical rooms are designed smaller to allow more living space.
3.  Should a generator transfer be included, a service disconnect is required which will require taking up horizontal space.

Another typical solution is the "old style" electrical panel designed for a home built in the 70's and 80's:  (See Figure 2)

Figure 2

Again, another design that is "okay" because it offers(Figure 2) very low cost in material, but is extremely high in labor costs.  For the same amperage service, but lower cost in labor, another answer would be the Square D NQ Panelboard. (See Figure 3).  But, it too has limitations:

1.  No expansion capabilities
2.  600-amp maximum main
3.  The height of 74" and 600-amps plus sub-fee breakers (150/200-amps, leaves ONLY 30 branch circuits available.  Too much space used for minimal branch  circuits.

So, what is the solution for the home or business that requires much higher amperage service and only provides a small mechanical room?  The Square D I-Line Combo Panelboard.  It offers up to 84 circuits (accepting either Plug-on or Bolt-on breakers), and allows 18-31.5 inches of mounting space of the I-Line breakers for larger subs all in one cabinet.  (Note:  the main lug and main breaker options are available up to 1200-amps). 

The Square D I-Line Combo Panelboard is available in a few phase services including:  (1)  3 ph 12/208, (2) 277/480v and (3) 1 ph 120/240v single-phase service, which is rated for both residential and commercial applications.

Following are the key points of the Square D I-Line Combo Panelboard:

1.  Up to 31.5 inches of mounting space
2.  Maximum of 1200-amp main breaker
3.  Maximum of 84 circuits (NQ panel sections) that accepts both Plug-on/Bolt-on breakers
4.  All AIC ratings available
5.  One or two section branch distribution
6.  Four back box selections
     - 26"w x 86"h
     - 32"w x 73"h
     - 32"w x 91"h
     - 44"w x 86"h
7.  Available in single or three-phase service in all voltages - up to 480v

(Figure 4 below)


Figure 4

At REVCO, we found that the best solution for this complex residential project was the Square D I-Line Combo Panelboard.  It offered the required amperage power in a nice, neat compact space.  

About Us

Founded in 1978, REVCO Lighting + Electrical Supply serves the residential, commercial, industry and retail markets throughout the region.  Expertise in LEDs, PSEG Commercial Energy-Efficiency Program, lighting control systems/home automation and electrical distribution systems from small-to-large scale projects.  Owned and operated by the Velys family, and a company built upon integrity, professionalism and providing superior customer service.  Visit

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