Low-voltage distribution boards and panelboards · interrupting and short-circuit rating, assembly standards, dead-front enclosures, circuit marking and lockable disconnects, working space and headroom
A power distribution panel, also called a distribution board or panelboard, takes an incoming supply and divides it into feeder and branch circuits, each protected by a circuit breaker or fuse, on busbars inside an enclosure. Ask three things first: what fault current the panel and its devices are rated to interrupt at your supply, which assembly standard it is built and tested to, and how much clear working space it needs where it will be installed.
Low-voltage main, sub and final distribution boards, panelboards and consumer units, indoor or outdoor, including explosion-proof distribution boards. Medium-voltage switchgear, motor control centres, empty enclosures and individual breakers sold alone are outside this page except where compared.
01
29 CFR 1910.303 requires equipment that interrupts fault current to have an interrupting rating sufficient for the nominal voltage and the current available at its line terminals, and requires overcurrent devices, circuit impedance and component short-circuit ratings to be coordinated so a fault is cleared without extensive damage. Equipment must carry the maker's identification and its voltage, current or other ratings, and where breakers or fuses are applied under a series combination rating, the enclosure must be marked to say so. [1]
CHINT states that its main distribution boards comply with IEC 61439, the standard for low-voltage switchgear and controlgear assemblies, and with IEC 60947 for circuit breakers and other components. [3] 29 CFR 1910.305 requires panelboards to be mounted in cabinets, cutout boxes or enclosures designed for the purpose and to be dead front, except where only qualified persons have access, and switchboards with exposed live parts to be in permanently dry places accessible only to qualified persons. [2]
Editorial note: ask the supplier for the assembly's rated short-time or conditional short-circuit current, the breakers' interrupting ratings, and the type-test or design-verification report, and compare them with the prospective fault current calculated at your point of installation.
Give the supplier the supply system (voltage, phases, earthing, frequency), prospective fault current at the panel, incoming rating and main device, number and ratings of outgoing circuits, metering and monitoring, installation (indoor, outdoor, hazardous area), ingress protection, mounting (wall or floor), cable entry, standards and certification required, and spare capacity.
02
For equipment likely to be examined or serviced while energized, 1910.303 sets the minimum working-space depth in Table S-1: for 0–150 V to ground, 0.9 m (3 ft) in all conditions; for 151–600 V, 0.9 m (3 ft) with live parts on one side only (Condition A), 1.0 m (3.5 ft) with grounded parts opposite (B) and 1.2 m (4 ft) with live parts on both sides (C). The space must be at least the equipment width or 762 mm (30 in), allow doors to open 90°, not be used for storage, and have headroom of 1.98 m (6.5 ft) for installations from 13 August 2007; switchboards and panelboards must sit in dedicated space. Every service, feeder and branch circuit must be durably marked with its purpose, and required disconnects must be capable of being locked open. [1]
Editorial calculation: a 480 V three-phase wye system has about 480 / √3 ≈ 277 V to ground, so it falls in the 151–600 V row; a panel facing a grounded wall (Condition B) needs 1.0 m (3.5 ft) clear in front, and facing other live equipment (Condition C) 1.2 m (4 ft). The system voltage is an assumed example; apply the rules in force where you install.
03
Suppliers linked to this page list distribution boards or panels; each card links to the page reviewed.
Listings include main and sub distribution boards, low-voltage switchgear and distribution cabinets, explosion-proof distribution boards, household and commercial distribution boards, and EV distribution boards. Companies listing only empty enclosures or lighting are hidden here. Ask each for rated current, short-circuit rating, assembly standard, IP rating and test reports.
04
The IEC webstore abstract for IEC 61439-3:2024 sets out the scope for distribution boards intended to be operated by ordinary persons (DBO), for example in domestic use. It covers enclosed, stationary assemblies for indoor or outdoor use with outgoing circuits rated (Inc) at no more than 125 A, an assembly rated current (InA) of no more than 250 A, and a nominal voltage to earth of no more than 300 V AC; voltage limits for DC are still under consideration. [4]
The 2024 second edition replaces the 2012 first edition, deletes the Type A and Type B DBO categories, and adds annexes for DBOs in a prosumer's electrical installation and for the rated current of a DBO with an additional parallel source of supply, for example PV. [4]
Editorial calculation: a 230/400 V supply has 230 V to earth and a 480Y/277 V supply 277 V, both within the 300 V AC limit. A board rated 400 A, or one with a 160 A outgoing circuit, exceeds the 250 A or 125 A limits and falls outside this part. If solar or another source feeds the board in parallel, ask which edition and annex the design verification followed.
05
This is a functional reference built from the sources cited; it is not one maker's specification.
| Part | Role | Fix in the order |
|---|---|---|
| Incoming device | Main breaker or switch; lockable. [1] | Rating and interrupting capacity. |
| Busbars | Distribute current. | Material, rating, short-time rating. |
| Outgoing breakers or fuses | Protect circuits. [1] [3] | Ratings and coordination. |
| Enclosure | Dead front; protection. [2] | Material, IP rating. |
| Neutral and earth bars | Return and protective conductors. | Sizes. |
| Circuit directory and labels | Identify every circuit. [1] | Durable marking. |
| Metering and monitoring | Measure loads. | Meters and communications. |
06
A distribution panel quotation needs values for your installation. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Main Incoming Current Rating (Amperes) | Incoming capacity. | Rated current. |
| Number of Circuits (count) | Outgoing ways. | Ways and spare. |
| Voltage Rating (Volts) | Sets working space row. [1] | Rated voltage. |
| Short Circuit Current Rating (kA) | Must cover available fault current. [1] | Assembly and device ratings. |
| IP Rating (IP code) | Environment. | Rating. |
| Dimensions (mm) | Working space width ≥ 762 mm or equipment width. [1] | Size and door swing. |
| Operating Temperature (°C) | Derating. | Range. |
| Rated Frequency (Hz) | Supply. | Frequency. |
| Enclosure Material | Dead-front enclosure. [2] | Material and finish. |
| Busbar Material | Copper or aluminium. | Material and rating. |
| Weight (kg) | Mounting. | Weight. |
| Degree of Protection | Assembly standard. [3] | Standard and test report. |
07
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Supply: [voltage; phases; earthing; frequency] Fault level: [prospective kA] Incoming: [rating; device] Outgoing: [number; ratings; types] Site: [indoor/outdoor; hazardous area; IP] Standards: [IEC 61439 or local code] Space: [dimensions; working space]
These companies list distribution boards or panels.
Lists main and sub distribution boards and final distribution boxes.
Product scope checked 2026-10-11
Lists LV distribution boards with switchgear and electrical cabinets.
Product scope checked 2026-10-11
Lists electrical distribution panels and cabinets with control panels.
Product scope checked 2026-10-11
Lists explosion-proof distribution boards and control systems.
Product scope checked 2026-10-11
Lists distribution boards including EV distribution boards with low-voltage equipment.
Product scope checked 2026-10-11
Lists distribution boards among electrical products.
Product scope checked 2026-10-11
Lists household distribution boards with PV and storage products.
Product scope checked 2026-10-11
Lists distribution boards with medium- and low-voltage distribution products.
Product scope checked 2026-10-11
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
Under 29 CFR 1910.303, 0.9–1.2 m deep depending on voltage and what is opposite, at least 762 mm wide, with 1.98 m headroom for newer installations. [1]
1910.303 requires interrupting ratings sufficient for the current available at the device's line terminals. [1]
CHINT cites IEC 61439 for low-voltage assemblies and IEC 60947 for the breakers and components. [3]
According to IEC's webstore abstract for IEC 61439-3:2024, boards operated by ordinary persons with outgoing circuits up to 125 A, an assembly rating up to 250 A and up to 300 V AC to earth. [4]
Sources checked 2026-10-11. 29 CFR 1910.303 and 1910.305 are US workplace electrical rules; CHINT is a switchgear maker describing its own boards. Other countries apply their own wiring rules.
Ask for use case, specification boundaries, supplier type, and RFQ preparation information for this product.
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