This blog post was written by Sam Fopma.
A proper electric room layout can prevent many headaches and set your facility up for future success.
Determining an electric room size and layout is often one of the first things to do when planning a new electrical project, but how do you start generating a layout when you don’t know the details of the electrical system? Here are five steps I use when developing concept electric room layouts:
Determine the usable work space
Did the building designer set a specific area for us to use or are we fitting into an existing building space? If it is a new building, start by sketching that space. In existing footprints or areas, understand your boundaries and sketch the limiting dimensions of the room you hope to use.
Set your egress paths
It is critical to know how to get people out of the room safely before you start placing equipment. Most electric rooms will need two doors: one general access door and one larger access/equipment door. Place the doors in the most logical spot for the building and show that egress doors swing out of the room.
Identify your service entrance location
Similar to the egress paths, knowing where your service conductors are coming from is essential. The service conductors are often quite expensive on a per-foot basis so locating the service gear closer to the transformer or upstream gear can help limit overall project cost.
Place your critical equipment
Now comes the fun part! First, use vendor websites to get a rough idea of the size of service gear (like switchboard and switchgear) you’ll need and place that in the location identified above. Next, identify the sizes for sub-distribution equipment (like distribution panels and MCCs) and add them to the room. Focus on minimizing the distance from the service gear to the sub-distribution equipment and orienting the sub-distribution equipment so that conduits can leave perpendicular to the gear and head out to the field. Also leave yourself some clean space for reserved “small items” and physical space for future expansion, if possible.
Evaluate equipment clearances and adjust
Now that all the equipment is placed, pull measurements and verify that the clearances between gear meet the requirements of NEC 110. Some key items to watch for:
- Keep live-to-live 480V gear a minimum of 4’ apart
- Keep live fronts of gear at least 3’6” away from walls and grounded faces of other gear
- Keep your egress paths to 3’ and only compromise if there is absolutely no alternative
Move items around until you find a way to meet the code requirements and a fit that works with your egress and expansion goals.
One final recommendation is to use paper cutouts or electronic drafting tools with a scale to do the layouts; at this stage it can take many iterations to get things to fit well and the flexibility to drag and drop is very useful. Thankfully at the end of the iterations you have a great starting point for continuing to plan a successful project.