BOI Factory Electrical Compliance Checklist — Bangkok & EEC Edition
Foreign manufacturers setting up under a Board of Investment (BOI) promotion in Thailand get attractive incentives — but the electrical compliance path is the same as any Thai factory, and it's where foreign project teams most often lose weeks. This is the practical electrical checklist for a BOI factory in Bangkok or the Eastern Economic Corridor (EEC).
1. Confirm your utility — MEA or PEA
Your supply authority depends on location, not on your BOI status. Bangkok, Nonthaburi and Samut Prakan are served by MEA; the rest of Thailand — including the EEC (Chonburi, Rayong, Chachoengsao) — is PEA. The application processes differ, so confirm this before you design anything.
2. Calculate load for the factory you'll have in 5 years
Size the customer substation and supply for forecast demand, not day-one load. Re-applying to upgrade capacity 18 months after start-up is slow and expensive. Include future lines, EV charging, and any planned solar.
3. Design to recognised standards — and name them
BOI and MNC head offices expect designs to recognised standards: IEC 60364 (LV installations), IEC 61439 (switchgear assemblies), TIS/มอก. cable standards, and NFPA where specified. Drawings should be signed by a Council of Engineers Thailand–licensed Professional Engineer — the licence number on the title block.
4. Plan the รง.4 factory licence and its electrical duty
Operating under a รง.4 factory licence carries an annual electrical-inspection obligation from day one. Build that into your maintenance plan before commissioning, not after your first audit.
5. Get the documentation set right
The minimum buildable, auditable package: single-line diagram (signed, dated), cable schedule, distribution-board schedules, calculation report (load, voltage drop, fault current, discrimination), and method statements. BOI factories are audited — incomplete documentation is a finding.
6. Coordinate protection across the whole system
From the main switchboard down to the final boards, protective devices must coordinate so a machine fault trips locally, not at the main incomer. For the switchboard hierarchy, see our guide to MSB vs MDB vs Sub-MSB.
7. Don't forget ELV and life-safety
Fire alarm, CCTV, access control and structured cabling are part of the compliance picture too — see what an ELV system includes. Fire detection in particular ties into your building life-safety approval.
8. Build a maintenance and inspection plan before you energise
The factories that stay compliant treat maintenance as continuous from start-up. Pairing your industrial electrical installation with a planned M&E maintenance programme means your annual inspection is a formality, not a scramble.
FAQ
Frequently asked questions
Does BOI status change the electrical application process?
No — the MEA/PEA supply application, standards and รง.4 inspection are the same as any Thai factory. BOI affects incentives and some approvals, not the electrical engineering path. A BOI certificate can, however, speed certain utility lanes.
How early should we engage an electrical contractor?
At the design stage, before equipment orders. The cheapest hour is the one that catches a sizing or compliance mistake before it's built.
What's the typical supply lead time in the EEC?
For an upgrade needing an MV transformer, realistically 10–16 weeks for PEA in the EEC — longer for a brand-new substation. Start the application early.
Who must sign the electrical drawings?
An engineer holding the appropriate Council of Engineers Thailand licence, with the licence number on the drawings. In-house drafters cannot self-certify.