BUILDING ELECTRICALSERVICES DESIGN FOR HOSTEL

ALONG NYERERE ROAD

Presented By : OELE O. COLLINS ERICKRegistration Number : F17/1999/2005Supervisor: Dr. N. AbunguExaminer: Mr. Dharmadhikary

PROJECT INDEX: PRJ 095

Objectives

• Lighting design• Power points layout design• Cables sizing• Power back-up system• Protection systems design• Power factor correction

Hostel Layout

Lighting Design

• Lighting design was done using the lumenmethod.

• For the lounge area within one hostel room :

Illuminance, E = 150 luxArea, A = (5.8m * 2.821m) = 16.36 m2

Flux of one light fitting, F = 2800 lumensUtility Factor, UF = 0.39Maintenance Factor, MF = 0.80

Sample Lumen Method of Lighting Design

ℎ ,= ×× ×= 150 × 16.362800 × 0.39 × 0.8 = 2.8≅ ℎ

Sample Lighting Design

Power Points

It consisted of :

• Twin socket power outlets- rated 13 A- connected in a ring circuit- three pins for line, neutral and earth cables

• Kitchen Unit

• Three phase isolators

- Lifts

Power Points Layout Design

Design Analysis

Using a worst case scenario of :

• 100 Watts for a single light fitting

• 1,000 Watts for a twin socket power outlet

Floor Total

load(Watts)

20% future load growth

factored in total load(Watts)

Lower 21,100 25,320

Upper ground 52,200 62,640

First 52,200 62,640

Second 52,200 62,640

Third 52,200 62,640

Attic 12,700 15,240

TOTAL 242,600 291,120

Summary for All Single-Phase Loads

Floor Total Current

drawn(Amps)

No. of CUs

Lower 105.5 2

Upper ground 261.0 3

First 261.0 3

Second 261.0 3

Third 261.0 3

Attic 63.5 1

TOTAL No. of Consumer units 15 CUs

Summary for All Total Currents Drawn

Distribution Topology of the ConsumerUnits

Consumer Unit Way Assignment• Circuit and way on CU

= UGF 1.1• Total load(watts)

= 900• Total current (amps)

= (900W/240V) = 3.75• MCB size

= 6A• Cable size(mm2 )

= 1.5

Consumer Unit, CU UGF 1

Load BalancingPhase Red Yellow Blue

Total Single-Phase Loads

(Watts)

81,933.36 80,033.36 80,633.36

Total Three-Phase Loads

(Watts)

66,000.00 66,000.00 66,000.00

TotalBalanced

Loads (Watts)

147,933.36 146,033.36 146,633.36

Current(Amps)

456.169 448.252 450.752

Sample Distribution Board, DB ‘B’ CableSizing

• Length of cable connecting DB ‘B’ at the atticfloor to the switchboard = 20m

• Current used for sizing the cable = 180 Amps.• Allowing for a maximum of 1.5% design

voltage drop on this cable• 0.3643% voltage drop is less than 1.5%• The 95mm2 cable is appropriate.

Power Back-Up Generator Size• Total hostel load = 308,600.08 Watts

• Applying 15 % future load growth= 308,600.08 * 1.15 = 354.89 Kilowatts

• Total hostel load in kVA with future load growthfactored in:

= 443.6125 kVA

• A 450 kVA, 50 Hz VOLVO generator size is chosen

Electrical Distribution Reticulation

Lightning Protection

Sample Discrimination Between CU UGF 1 and DB ‘A’

• Consumer unit= UGF1

• Distribution board feeding the CU= DB ‘A’

• Cable current capacity (Amps)= 79

• Cable current (Amps)= 70.98

• Rating of largest MCB in CU (Amps)= 20

• Fault current (Amps)= 769.29

• Rating of G FRAME MCCB Upstream in DB (Amps)= 100

Power Factor Correction

Cos-1 0.65 = 49.46˚

Cos-1 0.9 = 25.84˚

Apparent power (S)=327.89 kVA

Actual (REAL) power load consumption = kVA× cos ∅=327.89×0.65 = 213.1285 kW

Reactive power aftercorrection=213.1285 tan 25.84`=103.21 kVAR

kVAR before power factorcorrection=327.89×sin49.46 = 249.18 kVAR

Capacitor bank = 249.18

-103.21 =145.97 kVAR

Conclusions

• An appropriate lighting scheme anddistribution system layout was achieved.

• Various sizing of cables were discussed• Overload and short circuit protections were

provided for.• Power back-up generator was put in place

and its capacity determined.

Recommendations and Future Work

• Software for building electrical servicesdesigns.

-Computer programs and macrosfor mathematical computations

• A bill of quantities to estimate the cost• Earth Faults analysis

THANK YOU