Setting up the electrical system for a new factory unit is one of those tasks that owners often leave to the last minute - after the civil work is done, after the machinery is ordered, sometimes after the machinery has already arrived and is sitting waiting to be connected. Doing it in the right sequence, starting early, saves money and prevents the corrections that happen when electrical planning follows construction rather than informing it.
This guide is for factory owners taking a new shed in Waluj MIDC, Shendra MIDC or the broader MIDC belt around Chh. Sambhajinagar (Aurangabad). The sequence and the questions apply regardless of shed size, though the specific sizes and costs will scale.
Step 1: Load list before anything else
The load list is a table of every electrical load the factory will have: each motor with its HP rating, every HVAC unit, the welding sets if any, the office and lighting load, and any future expansion you can anticipate. From this list you calculate the total connected load in kW.
You then apply a demand factor - not every motor runs at full load simultaneously - to get your maximum demand. For a mixed machine shop this is typically 0.6-0.8. The maximum demand determines what MSEDCL connection capacity you apply for. Getting this wrong in either direction costs money: too small a connection and you face demand surcharges or cannot connect everything; too large and you pay a higher monthly demand charge even when utilisation is low.
Typical load ranges and corresponding MSEDCL connection sizes for MIDC units in Chh. Sambhajinagar:
- Up to 15 kW total connected load: single-phase 15 kVA connection may be sufficient for very small workshops. Most manufacturing units will need three-phase.
- 15-40 kW: three-phase 25 kVA LT connection. Suitable for a small machine shop with 3-4 motors up to 10 HP each.
- 40-100 kW: three-phase 50-100 kVA LT connection. Suitable for a mid-size auto component unit with several larger motors.
- Above 100 kW: 100 kVA or above LT connection, or HT connection for larger facilities. HT connections require a separate transformer and more complex metering.
Step 2: Single-line diagram
A single-line diagram (SLD) is a schematic that shows how power flows from the MSEDCL meter through the main switch, through the main panel (or MCC for larger factories), through sub-panels and to individual loads. It specifies bus bar ratings, MCB and MCCB ratings and trip settings, cable cross-sections, and earth points.
The SLD is the document that the installation is built from. An electrician who builds your factory installation without one is working from memory or judgment rather than design. This is how you end up with cable sizes that are too small, MCB ratings that do not coordinate (a minor fault trips the main breaker instead of the branch), or a panel that runs out of space when you add a second machine six months later.
After the installation is complete, the as-built SLD (updated to reflect any changes during installation) becomes a permanent record of your electrical system. A facility manager, a maintenance engineer, or an insurance inspector who needs to understand your installation uses it. Keep it with your premises documents.
Step 3: MSEDCL connection application
The MSEDCL three-phase commercial/industrial connection application requires the load list, a site plan showing the shed location in the MIDC plot, and sometimes a shed ownership or occupancy document. For MIDC sheds, a letter from MIDC confirming your allotment is usually sufficient.
Processing time in the Chh. Sambhajinagar circle has been 4-8 weeks in our experience for standard LT connections. HT connections take longer. Start the application as soon as you have the shed possession - do not wait for civil work to finish. The connection can be energised without machinery being installed; you just need the infrastructure to be ready.
Step 4: Installation sequence
The correct installation sequence is:
- Civil preparation first - conduit laying in walls and floors if required, earth pit excavation, cable trench if cables run underground between structures.
- Earth pits - install and test the earth electrodes before any electrical equipment is connected. This is IS 3043 practice and practical sense: the earth must be verified before the installation is live.
- Cable trays and conduit - before cables are laid. Trays should be sized for future expansion (50% fill now, 30% reserved).
- Main panel and sub-panels - mounted, busbar assembled, cable lugs crimped and terminated.
- Motor starters and control panels - DOL or star-delta starters wired before motor connections are made.
- Motor power and control cabling - power cables from starter to motor, control cables separately routed, motor frames bonded to earth bus.
- Lighting and utilities - industrial lighting, office wiring, CCTV and intercom power last.
Step 5: Commissioning tests before switching on
Before any motor or machine is energised for the first time:
- Insulation resistance (megger) test on every power circuit - 500V test for standard LT cables, 1000V for circuits above 250V. A reading below 1 MΩ is a fault. Factory-new cables should read well above 100 MΩ.
- Earth resistance measurement at each earth pit - should be below 1 ohm for industrial installations per IS 3043.
- Phase sequence check - before connecting any three-phase motor. Wrong phase sequence runs the motor backwards; this is a mechanical hazard and in some cases a pump or compressor damage risk.
- Voltage at each panel - check all three phases and measure imbalance. More than 2% imbalance should be reported to MSEDCL before starting motors.
- Overload relay settings - verified against each motor's nameplate FLA before first start.
Handover documentation
The electrician or contractor who completes the installation should provide you with:
- As-built single-line diagram (updated from the design SLD to reflect any field changes).
- Insulation resistance test report with circuit references and readings.
- Earth resistance measurement report with readings at each earth electrode.
- Phase balance check at incoming panel.
- List of materials installed: cable sizes and lengths, MCB/MCCB ratings, panel make and rating, motor starter types.
If your electrician does not provide this, ask for it explicitly. A factory installation without commissioning records is an installation whose condition you cannot verify - and cannot demonstrate to an insurance inspector or a regulator.
Indicative costs
Electrification costs for MIDC units in Chh. Sambhajinagar vary significantly with shed size, number of motors and panel complexity. Some rough benchmarks from recent projects in the Waluj and Shendra MIDC belt:
- Small unit (250-500 sq ft shed, 3-4 motors up to 10 HP, simple panel, basic earthing): roughly Rs 80,000 - 1,50,000 for the complete electrical installation excluding MSEDCL connection charges.
- Mid-size unit (500-1500 sq ft, 5-10 motors up to 30 HP, MCC or sub-panels, proper cable trays): roughly Rs 1,50,000 - 4,00,000.
- Larger units with VFDs, complex MCC, generator integration or HT connection: quote after detailed BOQ from SLD; estimates without a BOQ are not useful.
Material (cables, panels, breakers) typically accounts for 60-70% of the cost for a new installation. Do not buy materials separately without engineering input - the wrong cable size is not cheaper when it needs to be replaced after six months because it overheats under full load.
Once the factory is running, a preventive maintenance AMC from the first year of operation is the most cost-effective way to keep the installation performing and to build the documented maintenance history that banks and insurers ask for.
Details of our industrial electrical service for new factory electrification in Waluj MIDC and Shendra MIDC are on the service page. We provide the SLD, the full installation, commissioning tests and the complete handover documentation package.
