Distribution Boards
– North American distribution boards are housed in sheet metal enclosures.
– Circuit breakers are positioned in two columns operable from the front.
– Panelboards are more common in commercial and industrial applications.
– Residential and light commercial panels are referred to as load centers.
– Neutral conductors are secured to a neutral bus using screw terminals.
– UK distribution boards have three incoming phase wires and busbars for neutral and earth.
– Busbars are connected via a main switch in the center of the panel.
– Larger installations use three-phase supplies with twin vertical rows of breakers.
– Modern boards use circuit breakers and RCDs on DIN rail mountings.
– Main distribution board provides a main switch (incomer) for the whole supply.
Breaker Arrangement
– Breakers are usually arranged in two columns.
– Breaker positions are numbered left-to-right along each row from top to bottom.
– Each row is fed from a different line to allow 2- or 3-pole common-trip breakers.
– Large permanently installed equipment is wired line-to-line.
– Split-phase electric power provides 240V for split-phase and 208V for three-phase.
Fuse Boxes
– Common design of fuse box from 1940 to 1965 featured 60-amp fuse box.
– Fuse box included plug fuses for branch circuits and cartridge fuses for major appliances.
– After 1965, 100A panel with three-wire service became common.
– Fuse box could have fuse blocks for main shut-off and electric range circuit.
– Plug fuses were used for individual circuits.
Consumer Units
– Consumer unit is a type of distribution board in the UK.
– It is a coordinated assembly for the control and distribution of electrical power.
– Old consumer units were fitted with wire fuses.
– New consumer units are fitted with MCBs, RCDs, and switches.
– BS 7671 defines consumer units in the UK.
– Different types of consumer units offer varying levels of circuit separation and protection.
– Main switch consumer unit offers the highest degree of circuit separation.
– Main switch and Dual RCD consumer unit offers a cost-effective solution.
– High integrity consumer unit offers improved circuit separation and flexibility.
– Consumer units in the UK must provide RCD protection to all cables embedded in walls.
Safety Considerations and Innovations
– The choice of consumer unit depends on factors like the size and layout of the dwelling.
– Number of floors, outbuildings, and expected loads influence the selection.
– Different circuits may require different levels of protection.
– Older fuse boxes may not provide protection from accidental contact with live terminals.
– Wylex consumer units were popular in Britain until 2001 when RCD protection was mandated.
– Some manufacturers add innovative features like LED strip lights for enhanced visibility.
– Modern consumer units are non-combustible and use DIN-rail mounted devices.
– RCD protection is important for electrical safety in domestic premises. Source: https://en.wikipedia.org/wiki/Breaker_panel
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A distribution board (also known as panelboard, breaker panel, electric panel, fuse box or DB box) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure. Normally, a main switch, and in recent boards, one or more residual-current devices (RCDs) or residual current breakers with overcurrent protection (RCBOs) are also incorporated.
In the United Kingdom, a distribution board designed for domestic installations is known as a consumer unit.
