Glossary · also called Bill of Materials, Material list, Parts list
What is a BOM (Bill of Materials)?
BOM: A BOM (bill of materials) is a structured list of every component, sub-assembly and material needed to make one product, with the quantity of each. In an engineer-to-order business such as electrical panel building, the BOM is created for each job and, once priced with charges and margin, becomes the basis of the quotation, purchase and production.
Definition
Manufacturers that make the same product repeatedly keep a standard BOM and reuse it. Panel builders rarely can: each enquiry has its own single-line diagram, ratings and brand preferences, so the BOM is built per job. That makes the BOM the most important document in the business — it decides the price, the material to buy and what the shop floor builds.
A panel BOM usually covers switchgear and protection, metering, control components, busbar, enclosure, wiring and accessories, plus charges for fabrication, wiring labour, testing and packing.
How it works
A simplified example for a small distribution panel, with illustrative prices only:
| Item | Qty | Unit price (₹) | Amount (₹) |
|---|---|---|---|
| MCCB 125 A 4P (incomer) | 1 | 14,500 | 14,500 |
| MCB 32 A SP (outgoing) | 12 | 320 | 3,840 |
| Multifunction meter | 1 | 4,800 | 4,800 |
| Copper busbar set | 1 | 9,500 | 9,500 |
| Enclosure, powder-coated | 1 | 18,000 | 18,000 |
| Wiring, lugs, ferrules | 1 lot | 3,500 | 3,500 |
| Fabrication and wiring labour | 1 | 8,000 | 8,000 |
| Cost | 62,140 | ||
| Margin, 18% | 11,185 | ||
| Selling price before GST | 73,325 |
GST is added on the quotation at the applicable rate for the product’s HSN code. Larger panels such as an MCC panel or APFC panel follow the same structure with more groups.
Once the order is won, the BOM drives material: stock is reserved and shortages become a purchase requisition.
Common mistakes
- Out-of-date prices from old supplier lists.
- Missing small items — CTs, control transformers, terminals — that come straight out of margin.
- Rebuilding from scratch for every enquiry instead of starting from a template.
- Quoting one brand only when the customer would accept alternatives, which makes it harder to meet a target price.
- A BOM that stops at the quotation, so purchase and production work from different lists.
In Zaptiz
Zaptiz Electrical builds BOMs from panel templates, from PDF or image drawings, from photos of existing panels or from a plain-English spec, with brand tiers, charges and margin. See panel BOM software.