Allison Brown - Penn State College of Engineering



Introduction

Emergency Egress Lighting Redesign

Emergency Egress Lighting Redesign (cont.)

Emergency Egress Lighting Redesign Summary:

EDP Adjustments

*Note: For economical reasons, I decided to parallel two sets of 4/0 instead of using 600 MCM wire.

New EH1 Panel Schedule

Adjusted Panel and Feeder Schedules

Riser Diagram

*Note exhaust fans are fed from EDP*

Generator Resizing

*See appendix for generator calcs*

Cost Comparison Analysis

Feeder Cost Comparison Analysis (cont)

Emergency Redesign Summary

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For the electrical depth study, an analysis was performed in investigating the possibility of eliminating battery powered fixtures used for emergency lighting in the building and placing existing normal power fixtures on life safety circuits. A 150 KW (.80 pf), diesel engine, emergency generator already exists in the building. It is designed to supply power to three Y-Δ starting atrium exhaust fans and a few small fire protection devices. First, a new design for lighting egress using existing normal fixtures and the elimination of battery packs was determined. Next, new and adjusted panel sizes with adjusted feeder sizes, and the size of the generator needed to handle the existing loads were determined. To compare the results, a cost-savings analysis was performed considering both maintenance and hard costs.

The following charts show the number of existing fixtures on each floor level designed to be put on life safety circuits. The first floor lobby already has egress lighting fixtures fed from the generator.

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In the existing stairwell towers there are

two A12 bracket fixtures on each floor with emergency ballasts. My design when considering placing these fixtures on life safety, is to place two 20 amp circuits feeding every other light fixture in the stairwells for precautionary purposes. In this way if one circuit would fail or break, the stairwells would not be left in total darkness.

In the spaces including my lighting redesign on the 4th floor, an emergency lighting plan was determined which will be explained later in my report.

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The existing load on the EDP is 188 KVA and the new load is around 253 KVA. This constitutes an increase in panel, breaker, and feeder size.

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By analyzing the emergency loads on the respected floors, I decided to feed the egress stairwells, lower level parking, and mechanical rooms directly from the EDP.

Considering the remainder of the load, I determined it would be best economically and best maintenance wise to feed 1 separate lighting panel EH1 to serve the remainder of the emergency lighting circuits on the 2nd, 3rd, and 4th floors. I decided to place the panel on the 3rd floor to minimize wire run.

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Typical Emergency Layout

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For my cost comparison analysis, I used data in RS Means Electrical Cost Data 25th ed to calculate the difference in removing the battery powered fixtures and replacing existing fixtures on emergency egress power. I considered the increase in the EDP feeder and generator size, the addition of 1 60 amp egress panel, and corresponding branch circuits. I did not include the difference between normal and emergency ballasts, however.

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The cost difference between increasing the generator size, adding a new life safety panel board, and eliminating the battery fixtures saves $5400.00. The cost difference in feeder and branch circuit increase is $7,243.66. Eliminating the battery powered fixtures and putting emergency fixtures on life safety will cost an additional $1,843.00. This difference, however, doesn’t consider future replacement and maintenance costs of the battery fixtures and is rather insignificant given the large budget for the building. Other advantages and disadvantages are listed on the right. Since the owner had already committed to a generator, it would be practical for the generator increase and addition of a life safety system. This would allow for easy expansion, avoid the hassle of maintenance/replacement costs, and de-clutter the interior spaces.

To accommodate the added emergency lighting load, I increased the generator size from 150 KW to 200 KW. Since the exhaust fans are reduced Y- Δ starting, the engine size is mainly dependent on the KW rating of the combined load rather than the effective starting KVA of the motors.

When considering the differences between gas and diesel, both options work perfectly in most situations, however beyond 100 KW, gas sets are very expensive because the engines are de-rated and would not be cost effective.

Another consideration is since the genset will be used for life safety, it must have an uninterruptible fuel supply. Since natural gas is a utility service, it is considered interruptible.

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