Electrical DB Box Buying Guide for Bangladesh: Sheet, IP Rating, Glands and Earthing

What an electrical DB box has to do

A distribution board (DB) box or electrical enclosure looks like a simple steel box, but it carries several responsibilities at once:

• Protect people from touching live parts.
• Protect equipment inside from dust, lint, water, insects and impact.
• Contain faults, limiting the spread of sparks or a small internal fire.
• Provide a safe earth path for the metalwork.
• Give working space for wiring, cable bending and future changes.

In Bangladeshi factories, the environment makes some of these harder: cotton lint in RMG and spinning units, humidity and condensation during the monsoon, wash-down in food plants and salt air near the coast. Specifying the enclosure properly at the start is far cheaper than replacing corroded or overheated boxes later.

Electrical design, ratings of breakers and busbars, and compliance with electrical regulations remain the responsibility of your electrical engineer. This guide covers the enclosure. Critical electrical rooms may also need automatic protection; see fire suppression systems and the FM200 vs CO2 comparison. See the electrical DB boxes category for the product range.

Sheet material, thickness and construction

The outside dimensions tell a fabricator very little. These are the details that determine quality:

For reference, Safety Plus fabricates cabinets in 1.2–2.0 mm sheet, MIG-welded mild steel or stainless steel. As a rule, small wall-mounted DBs can use the thinner end of the range, while larger or floor-standing enclosures and those in heavy-traffic areas benefit from heavier sheet and stiffened doors. Ask the fabricator to state the thickness of every part on the drawing.

IP rating basics: what the two digits mean

The IP (Ingress Protection) code, defined in IEC 60529, describes how well an enclosure keeps out solid objects and water. It has two digits.

First digit — protection against solid objects and dust

Second digit — protection against water

So IP54 means dust-protected and protected against splashing water, while IP65 means dust-tight and protected against water jets. Your electrical engineer should choose the IP level from the location: a clean, dry electrical room needs far less than an outdoor pump station or a wash-down food line.

Two cautions. First, an IP rating is a tested claim; ask any supplier how it was verified. Second, the installed IP rating depends on the gasket, the cable glands and the installer. One unsealed cable entry turns a well-built box into an open one.

Gland plates and cable entry

Cable entry is where most enclosures are damaged and where most IP failures start.

• Removable gland plates at the top, bottom or both let the electrician drill holes on the bench without swarf falling onto live equipment, and allow future changes without cutting the body.
• Undrilled vs pre-punched: undrilled plates give flexibility; knockouts suit standard installations. Unused knockouts must be sealed.
• Gasketed plates keep the IP rating at the cable entry.
• Entry position: bottom entry is usual for floor-standing boards and where water could run down cables; top entry is common for wall DBs fed from cable trays. Avoid top entry in wet locations unless glands and drip protection are designed for it.
• Cable bending space: leave room between the gland plate and the first terminals so large cables are not forced into sharp bends.

State the number and size of cables on your drawing so the fabricator can size the gland plate correctly.

Earthing provisions

Every exposed metal part of an enclosure must be reliably connected to earth so that a fault makes the protective device trip instead of making the box live. A well-fabricated enclosure makes this easy:

• Welded earth studs on the body and on the inside of the door.
• Flexible earth bonding strap between door and body, because hinges are not a reliable earth path.
• Earth stud on the mounting plate or a bonded connection to the body.
• Earth bar sized for the incoming and outgoing protective conductors, where the design calls for it.
• Masked contact points: powder coating is an insulator, so earth studs and contact areas should be masked before coating, or the coating removed and protected afterwards.
• Earth symbol labels at each earth point.

The electrical engineer designs the earthing system; the enclosure must simply provide clean, accessible, properly sized points for it. Ask the fabricator to show earth points on the drawing.

Finish, ventilation and environment

The enclosure's finish decides how it looks in five years. Safety Plus surfaces are chemically de-rusted, zinc phosphate coated and finished with oven-baked powder paint. Light grey is a widely used colour for electrical enclosures, but any RAL colour can be specified. For more detail, see powder coated steel fabrication.

Heat and moisture also need attention:

• Ventilation louvres with filters let heat escape from boards with drives or many breakers, but reduce the IP rating; balance the two with your engineer.
• Condensation during the monsoon can wet terminals inside sealed boxes. Your engineer may specify anti-condensation measures for critical outdoor boards.
• Rain canopies and sloped tops help outdoor enclosures shed water.
• Lint and dust: in textile and garment plants, keep louvres filtered and include enclosure cleaning in maintenance.

For textile facilities, the RMG and textile page lists related products.

Custom fabrication to your drawing

Many projects need enclosures that do not exist in a standard catalogue: a particular footprint for a plant room, door cut-outs for meters and indicator lamps, a specific mounting plate layout or stainless steel for a pharmaceutical area. Safety Plus fabricates DB boxes and enclosures to drawing at its factory in Demra, Dhaka.

To get an accurate quotation, send:

1. General arrangement drawing or sketch with outside dimensions and depth.
2. Material and sheet thickness for body, door and mounting plate.
3. Wall-mounted or floor-standing; plinth if required.
4. Door type: single or double, hinge side, lock type, gasket.
5. Cut-outs on the door for meters, lamps, push buttons or viewing windows.
6. Gland plate position, size and drilling.
7. Earthing points required.
8. Finish and RAL colour; IP target set by your engineer.
9. Quantity and delivery location.

Prices are quotation-based and depend on these details. Send your drawing via the request a quote page, or read more about the factory on the manufacturing page. For heavy industrial applications, see power and industrial plants.

Frequently asked questions