A good practice is to become very familiar with the plans early on to avoid things that could create a problem later on during the construction process. Always look through the entire set of plans, not just the electrical pages.

Becoming familiar with systems and equipment the other trades are installing will help you be prepared for anything. For example, knowing where plumbing piping will be run, or knowing where the HVAC system installers will route their ductwork is critical.

Sometimes the electrician tries to get a head start overhead before the grid ceiling is installed. It’s great to be ahead of schedule and able to install all disconnect switches for the above ceiling air handlers and VAV (variable air volume) boxes before the actual HVAC equipment it installed but not at the expense of having to relocate many of them later due to insufficient working space required for the disconnect switches because the HVAC installer detoured from the plans when routing the ductwork. NEC^® 110.26(A)(4) provides the working space requirements for disconnect switches in areas such as above a ceiling where there is limited access.

Similar issues occur with panelboards which require dedicated space in accordance with NEC^® 110.26(E). Dedicated space is a required space for switchboards, switchgear, panelboards, and motor control centers. The dedicated space is equal to the width and depth of the equipment and extending from the floor to a height of 6 feet above the equipment or to the structural ceiling, whichever is lower. This area is dedicated to the electrical installation. No piping, ducts, leak protection apparatus, or other equipment foreign to the electrical installation can be located in this zone.

One installation that comes to mind (see image) involved a situation where the panelboard cabinets were installed in the electrical room exactly where the plan showed them, but yet the ductwork overhead that ran through the entire room was encroaching into the dedicated space needed for the panelboards. On the HVAC (mechanical) pages of the plans, the ductwork measurements showed that there would still be barely enough dedicated space for the panelboards but that was because the plans only showed the outside dimensions of the ductwork, not the additional thickness of the specified duct wrap that was added after the ductwork was in place.

The problem was, it was the electrical code that required the dedicated space for the panelboards, not the mechanical code, therefore the electrical inspector had to write the red tag to the electrician for the code violation. It then became a legal matter and a blame game with the electrical engineer who drew the electrical plans, as well as the architect having to foot the bill to fix the issue. Even though the electrician followed the plans, the code violation created a huge delay in final inspection approval. If the electrician had thought about the ductwork being installed over the panelboards when it was occurring, he might have been able to bring it up to the electrical engineer earlier so that a solution could have been in the works long before requesting a final inspection right before the grand opening.

The fix ended up being an additional structural ceiling being installed directly above the panelboards but under the ductwork which technically made the ductwork now above the structural ceiling and out of the required dedicated space for the panelboards.

Below is a preview of the NEC^® (NFPA 70). See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the edition of the NEC^® being enforced.

NEC 110.26(A)(4) Limited Access. Where equipment operating at 1000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized is required by installation instructions or function to be located in a space with limited access, all of the following shall apply:

(a) Where equipment is installed above a lay-in ceiling, there shall be an opening not smaller than 559 mm × 559 mm (22 in. × 22 in.), or in a crawl space, there shall be an accessible opening not smaller than 559 mm × 762 mm (22 in. × 30 in.).

(b) The width of the working space shall be the width of the equipment enclosure or a minimum of 762 mm (30 in.), whichever is greater.

(c) All enclosure doors or hinged panels shall be capable of opening a minimum of 90 degrees.

(d) The space in front of the enclosure shall comply with the depth requirements of Table 110.26(A)(1). The maximum height of the working space shall be the height necessary to install the equipment in the limited space. A horizontal ceiling structural member or access panel shall be permitted in this space.

NEC 110.26(E) Dedicated Equipment Space. All switchboards, switchgear, panelboards, and motor control centers shall be located in dedicated spaces and protected from damage.

Exception: Control equipment that by its very nature or because of other rules of the Code must be adjacent to or within sight of its operating machinery shall be permitted in those locations.

(1) Indoor. Indoor installations shall comply with 110.26(E) (1)(a) through (E)(1)(d).

(a) Dedicated Electrical Space. The space equal to the width and depth of the equipment and extending from the floor to a height of 1.8 m (6 ft) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. No piping, ducts, leak protection apparatus, or other equipment foreign to the electrical installation shall be located in this zone.