ELECTRICAL SYSTEMS RULES OF THUMB:
1. Electrical Room Requirements
a. |
On larger facilities, the main room typically needs two doors, one at each end of room (not double doors at one location). |
b. |
Doors must open in the direction of egress from the room. |
c. |
Doors must have panic hardware. |
d. |
Rated Construction: It is not typical that this room be required to have a 1 hour rating. If the electrical engineer needs a large transformer (a transformer with a rating over 112.5KVA) in this room, they should notify the Architect that the room will be required to have a 1 hour rating due to the National Electrical Code requirements. |
2. Electrical Room Sizing for Typical Facilities (recreation centers, multi-family, general commercial)
| Size of Facility |
Main Elec Room |
Remote Elec Rooms Rqd? |
Remote Elec
Room Size |
Notes |
| 0-20,000 sf, one level |
10’ x 20’ |
Typically not |
N/A |
(1) |
| 20,000 – 40,000 sf multi-levels |
15’ x 20’ |
One on main level and one per 20,000 sf on upper level(s) |
8’ x 10’ each |
(1) |
| +40,000 sf |
15’ x 20’ |
On each level, one per 20,000 sf and space 200’ apart |
8’ x 10’ each |
(1) |
(1) Additional remote electrical rooms should be considered for buildings with distinct space layouts which may benefit from additional localized distribution equipment. (i.e. An individual wing of building that is separated from the main building by multi-story open atrium).
3. Exterior Service Transformer (note that all specific electrical utility transformer requirements are to be coordinated with the local utility engineer for the project as most utility companies vary their requirements)
a. |
Less expensive if transformer is located near electrical room. |
b. |
For medium to large facilities anticipate 8’x 8’ pad size. |
c. |
Provide 36” clear around three sides, and 12’ of clearance on front side. |
d. |
Typically drive up access is required for the utility company. |
e. |
It is desirable to locate the electrical room on an exterior wall, near the final utility transformer location. |
4. Phone/data Rooms
a. |
Typically at least one per level of any building type. Cable can be routed 300’ from device to room, so additional rooms would be required for buildings longer than 300’ in any direction. |
b. |
Room sizes vary based upon the IT department’s needs, but anticipate
10’x 10’ for main telephone rooms and 6’x 6’ for remote rooms. |
5.Walls throughout the facility containing recessed electrical panelboards should be a minimum of 6” deep.
LIGHTING SYSTEMS RULES OF THUMB:
1.
Lighting is 30% of the overall building power usage. Savings in the overall watts/sf used for lighting can have a significant impact.
2. Typical 2 x 4 lighting fixture spacing is 8’ x 10’.
3. Wall mounted lighting fixtures can only be mounted below 6’-8” if they project 4” or less from the wall.
4. A typical building will end up with an overall lighting load of 1.0 – 1.5 watts per square foot.
5. Energy efficiency of typical lamps
a. |
One 32 watt fluorescent T8 has the equivalent light output to three 60 watt incandescent A Lamps (the standard household screw in lamp) or two 60 watt halogen MR16 lamps. |
b. |
Fluorescent High Output T5 – similar efficiency to the T8 fluorescent but its smaller size can lead to more efficient fixture design. |
c. |
Metal Halide is approximately 15% less efficient than fluorescent. |
d. |
LED actually has a very low light output per watt. Its overall energy efficiency is similar to standard halogen, far less than fluorescent lamps. The reason LED technology is said to be so efficient is because it directs most of the light in one direction so it is good for signs, stoplights, wayfinders, and other directional lighting, but not necessarily efficient for overall room illumination. |
6. Typical lamp life
a. |
Fluorescent T8 – 20,000 hours, or 3 years at 18 hours/day |
b. |
Fluorescent High Output T5 – 20,000 hours , or 3 years at 18 hours/day |
c. |
Metal Halide – 20,000 hours, or 3 years at 18 hours/day |
d. |
Incandescent A Lamp – 750 hours, or 2 months at 18 hours/day |
e. |
Incandescent MR16 Halogen – 10,000 hours (with special lamp), or 1-1/2 years at 18 hours/day |
f. |
LED – 100,000 hours, or +15 years at 18 hours/day |
7. To help with preliminary site budget costs, before an engineer may be involved on a project, the typical spacing of pole lights in a parking lot is approximately 100’ on center with an anticipated installed cost for non-decorative poles of $2,000 each. Decorative poles will typically be approximately $3,000 installed.
8. Due to the adoption of the International Building Codes, compliance with the International Energy Conservation Code is also typically required. Upon submission of the 100% CD drawings to the building department, it should be anticipated that stamped copies of the compliance forms be submitted by the electrical and mechanical engineers.
Download Electrical Systems Rules of Thumb printable sheet for reference.
Download Lighting Systems Rules of Thumb printable sheet for reference.
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