Electrical Design Firm in Bangladesh

An electrical design firm in Bangladesh prepares the engineering behind a building's or factory's power system before anything is installed: load calculation, single line diagram, cable and breaker sizing, protection coordination, earthing, lightning protection and lighting and power layouts. The drawings follow BNBC 2020 and IEC 60364 so the installation is safe, approvable and buildable.

Last updated: 7 October 2026Part of: Engineering services

Choosing an electrical design firm in Bangladesh is one of the earliest and most important decisions on any building or factory project. The design fixes the size of the substation, the cable routes, the protection settings and the earthing system, and every one of those choices is difficult to change once walls are finished and machines are running. TOTO POWER Engineering has worked as an engineering consultancy since 2011 and is enlisted with the Department of Inspection for Factories and Establishments (DIFE). Our electrical engineers design power systems for RMG and industrial units, commercial buildings and residential projects from our Dhaka and Chittagong offices.

What is electrical design?

Electrical design is the engineering work that decides how power gets from the utility supply to every light, socket and machine safely and reliably. It starts with the loads: what equipment will be connected, how much power it draws and how often it runs. From that, the designer calculates maximum demand, chooses the supply voltage, sizes the transformer and generator, lays out the distribution system, sizes every cable and protective device, and designs the earthing and lightning protection that keep people safe when something goes wrong.

The result is a set of drawings and calculations that a contractor can price and build from, an authority can review, and a maintenance team can rely on for years. A competent electrical engineering company in Bangladesh also thinks about the future: spare capacity, space for extra panels and cable routes that can take additional circuits without a rebuild.

Who needs an electrical design company in Bangladesh?

• Factory owners building a new RMG, textile or industrial unit, or adding production lines that change the total load.
• Developers and architects who need coordinated electrical drawings for apartment, office and commercial buildings.
• Compliance managers whose sites have grown without a proper design and now need corrected drawings after an electrical safety assessment.
• Contractors who must build to a stamped design and need a consultant to answer technical queries during installation.

What does our electrical design service include?

Load calculation and maximum demand

We build a load schedule for every distribution board, apply demand and diversity factors based on how the building will actually be used, and calculate maximum demand at each level of the system. This number drives every decision that follows, so we check it against similar operating buildings rather than adding up nameplate ratings blindly.

Single line diagram (SLD) design

The single line diagram shows the whole system on one sheet: incoming supply, HT switchgear, transformers, generators, changeover arrangements, main LT panels, sub-main distribution boards, power factor correction and major motor loads, with ratings for each device and cable. As a single line diagram (SLD) firm in Bangladesh we produce design SLDs for new projects. For an existing site that needs its installed system traced and documented, see our dedicated as-built SLD service.

Cable sizing and voltage drop

Each cable is sized for its load current, corrected for installation method, grouping and ambient temperature, then checked for voltage drop and short-circuit withstand. Undersized cables are one of the most common causes of overheating we find in Bangladeshi factories, and they usually start with a design that was never calculated.

Protection coordination

We calculate prospective fault currents, select breaker breaking capacities, and set protective devices so that the device nearest a fault trips first and the rest of the plant keeps running. Earth fault protection and residual current devices are specified where they are needed for shock protection.

Earthing and lightning protection design

Earthing design covers system earthing for transformers and generators, protective earthing for equipment, and equipotential bonding. For lightning, we assess the risk and design air terminals, down conductors and earth terminations in line with IEC 62305. Where you also need installation, our lightning protection system team can build what we design.

Lighting and power layouts

Lighting layouts are based on the illumination each area needs, such as production floors, stores, offices and stairs, including emergency and exit lighting. Power layouts locate sockets, machine outlets, isolators and distribution boards, with cable tray and conduit routes coordinated with the architecture and other services.

Substation, transformer and generator sizing

We size the HT supply, transformers, generators and power factor correction, and lay out the substation room with clearances, ventilation, cable trenches and access. If you are sourcing equipment, see our transformer range.

How is an electrical design prepared?

1. Brief and data collection. We collect architectural drawings, the machine and equipment list, the utility supply details and your plans for expansion.
2. Load assessment. We prepare load schedules and calculate maximum demand for each board and for the whole site.
3. System concept. We propose the supply arrangement, transformer and generator capacity, and the distribution structure, and agree it with you.
4. Detailed calculations. Cable sizing, voltage drop, fault level, protection coordination, earthing and lightning protection are calculated and recorded.
5. Drawings and schedules. We produce the SLD, layouts, panel schedules and specifications, then a bill of quantities for tendering.
6. Review and issue. Drawings are checked by a senior engineer, revised after your comments and issued for approval and construction.
7. Construction support. On request, we answer contractor queries and inspect the installation against the design.

What you receive

• Load schedules and a maximum demand calculation
• A design single line diagram with device and cable ratings
• Cable sizing, voltage drop and fault level calculations
• Protection coordination settings
• Earthing and lightning protection drawings
• Lighting and power layout drawings with cable routes
• Substation, transformer and generator room layouts
• Panel and distribution board schedules
• Technical specifications and a bill of quantities

Design SLD or as-built SLD?

Which standards apply?

The Bangladesh National Building Code (BNBC) 2020 includes an electrical part that sets requirements for building services, and IEC 60364 is the international reference for low-voltage installations. Lightning protection follows IEC 62305, and earth resistance measurements follow IEEE 81 methods. For factories, the Bangladesh Labour Act 2006 and Labour Rules 2015 and the DIFE inspection regime apply once the building is in use, and many export buyers add their own safety requirements. The utility and the relevant approving authorities may also set conditions for the HT connection and substation.

What does electrical design cost in Bangladesh?

There is no fixed price. The main cost factors are the floor area and number of buildings, the connected load, whether the scope includes an HT substation, generators and power factor correction, the number of drawings and layouts, whether tender documents are needed and how much site support you want during construction. Send us your architectural drawings and equipment list and we will reply with a written quotation.

Why choose TOTO POWER Engineering as your electrical design firm?

Our designers work alongside engineers who carry out electrical safety assessments and tests every week, so our designs are shaped by the faults we find in real installations. We can take a project from design through to electrical installation and testing, or provide the design alone for your contractor to build. See our complete electrical solution for the full range of electrical engineering work we offer, and all engineering services for structural, fire and testing support on the same project.