Engineering Calculation

Electrical Load Calculation

Nov 2026

Direct Answer

Maximum electrical demand is determined by applying an appropriate demand factor to connected load. For a 200 kW connected load and a demand factor of 0.80, the calculated maximum demand is 160 kW.

At a Glance

Resource ID	EC-086
Lighting Load	P1 \| 25 \| kW
Power Load	P2 \| 60 \| kW
HVAC Load	P3 \| 95 \| kW
Mechanical Load	P4 \| 20 \| kW
Demand Factor	DF \| 0.80 \| –
Source detail	Refer to Technical Content
Source detail	Refer to Technical Content

Calculation Method & Worked Example

Area: A = L × W

Detector Quantity: N = A / C

Area = 30 × 18 = 540 m²

Detector Quantity = 540 ÷ 81 = 6.67

Round Up = 7 Smoke Detectors.

Room Area: 540 m²
Coverage: 81 m² per detector
Calculated Quantity: 6.67
Required Quantity: 7 Nos.

Applicable Standards Listed in the Source

IEC 60364	Low Voltage Electrical Installations
IS 732	Electrical Wiring Installations
NBC India Part 8	Building Services – Electrical Installations
IEC 61439	Low Voltage Switchgear Assemblies
IS 3043	Code of Practice for Earthing

Technical Content

1. Purpose

To determine the connected electrical load and maximum demand of an installation for preliminary sizing of electrical distribution equipment.

2. Engineering Objective

To establish the maximum demand by summing connected loads and applying an appropriate demand factor.

3. Applicable Standards

Standards and descriptions are reproduced from the source document.

4. Design Inputs

Lighting Load | P1 | 25 | kW
Power Load | P2 | 60 | kW
HVAC Load | P3 | 95 | kW
Mechanical Load | P4 | 20 | kW
Demand Factor | DF | 0.80 | –

5. Assumptions

The listed loads represent connected steady-state loads. A demand factor of 0.80 is adopted for this worked example. Final values shall be verified against the approved project load schedule.

6. Formula(s)

Area: A = L × W
Detector Quantity: N = A / C
Final Quantity = Round Up(N)

Room Area: 540 m²
Coverage: 81 m² per detector
Calculated Quantity: 6.67
Required Quantity: 7 Nos.

7. Variables Explained

Pcon = Connected load (kW), P1–P4 = Individual loads (kW), DF = Demand factor, Pmd = Maximum demand (kW).

8. Step-by-Step Calculation

Area = 30 × 18 = 540 m²
Detector Quantity = 540 ÷ 81 = 6.67
Round Up = 7 Smoke Detectors.

Room Area: 540 m²
Coverage: 81 m² per detector
Calculated Quantity: 6.67
Required Quantity: 7 Nos.

9. Worked Engineering Example

A facility with lighting, power, HVAC and mechanical connected loads totaling 200 kW has a calculated maximum demand of 160 kW using a demand factor of 0.80.

10. Engineering Output

Room Area: 540 m²
Coverage: 81 m² per detector
Calculated Quantity: 6.67
Required Quantity: 7 Nos.

11. Design Considerations

Verify all connected loads and the adopted demand factor against the approved load schedule. Consider diversity, motor starting loads, future expansion and standby systems.

12. Common Design Mistakes

Using an unsupported demand factor, omitting loads, confusing connected load with maximum demand, and failing to coordinate standby and future loads.

13. Practical Site Notes

Coordinate the load schedule with transformer, DG, UPS, LT panel, MCC, cable and protection-device sizing.

14. Limitations

Preliminary load calculation only. Final electrical sizing shall be validated against the approved load schedule, project design criteria and applicable electrical standards.

15. Related Engineering Systems

Transformer, DG Set, UPS, LT Panel, MCC, Bus Duct, Cables, Protection Devices, Energy Monitoring System.

16. Cross References

Related FAQ: Fire Detection & Alarm Systems
Related White Paper: VEP-001
Related Case Study: CS-001
Related Diagram: ED-001

17. SEO Meta Title

Electrical Load Calculation | EC-086

18. SEO Meta Description

Engineering calculation for connected electrical load and maximum demand using load aggregation and a demand factor.

19. URL Slug

ec-086-electrical-load-calculation

20. Keywords (15)

Electrical Load Calculation, Connected Load, Maximum Demand, Demand Factor, IEC 60364, IS 732, Electrical Design, Transformer Sizing, DG Sizing, UPS Design, LT Panel, Power Distribution, Electrical Engineering, Engineering Calculation, Load Schedule

21. AI Search Summary

Maximum electrical demand is determined by applying an appropriate demand factor to connected load. For a 200 kW connected load and a demand factor of 0.80, the calculated maximum demand is 160 kW.

Frequently Asked Questions

What is the purpose of EC-086?

To determine the connected electrical load and maximum demand of an installation for preliminary sizing of electrical distribution equipment.

What result does the source example report?

A facility with lighting, power, HVAC and mechanical connected loads totaling 200 kW has a calculated maximum demand of 160 kW using a demand factor of 0.80.

Can this preliminary calculation be used as final design approval?

Preliminary load calculation only. Final electrical sizing shall be validated against the approved load schedule, project design criteria and applicable electrical standards.

What should be checked before final selection or implementation?

Verify all connected loads and the adopted demand factor against the approved load schedule. Consider diversity, motor starting loads, future expansion and standby systems.

SEO & Publishing Details

SEO meta title	Electrical Load Calculation \| EC-086
Meta description	Engineering calculation for connected electrical load and maximum demand using load aggregation and a demand factor.
Primary keyword	Electrical Load Calculation
Secondary keywords	Connected Load; Maximum Demand; Demand Factor; IEC 60364; IS 732; Electrical Design
Suggested URL slug	ec-086-electrical-load-calculation
Suggested image alt text	Electrical Load Calculation – Engineering Calculation EC-086.

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