Junction box

Short description: Enclosure housing electrical connections

Not to be confused with Box junction.

Relevant topics on

Electrical installations
Wiring practice by region or country

* North American practice
* United Kingdom practice

Regulation of electrical installations

* BS 7671 UK wiring regulations
* IEC 60364 IEC international standard
* Canadian Electrical Code (CE Code)
* U.S. National Electrical Code (NEC)

Cabling and accessories

* AC power plugs and sockets
* Cable tray
* Electrical conduit
* Mineral-insulated copper-clad cable
* Multiway switching
* Steel wire armoured cable
* Ring main unit
* Ring circuit
* Thermoplastic-sheathed cable

Switching and protection devices

* AFCI
* ELCB
* Electrical busbar system
* Circuit breakers
* Disconnector
* Fuse
* Residual-current device
* Distribution board
* Consumer unit
* Electrical switch
* Earthing system

* v
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* e

An electrical junction box (also known as a "jbox") is an enclosure housing electrical connections.[1] Junction boxes protect the electrical connections from the weather, as well as protecting people from accidental electric shocks.

## Contents

* 1 Functions of the junction box
* 2 Solar panel
* 3 See also
* 4 References
* 5 External links

## Functions of the junction box

A small metal, plastic or fiberglass junction box may form part of an electrical conduit or thermoplastic-sheathed cable (TPS) wiring system in a building. If designed for surface mounting, it is used mostly in ceilings, concrete or concealed behind an access panel—particularly in domestic or commercial buildings. An appropriate type (such as that shown in the gallery) may be buried in the plaster of a wall (although full concealment is no longer allowed by modern codes and standards) or cast into concrete—with only the cover visible.

It sometimes includes built-in terminals for the joining of wires.

A similar, usually wall mounted, container used mainly to accommodate switches, sockets and the associated connecting wiring is called a pattress.

The term junction box may also be used for a larger item, such as a piece of street furniture. In the UK, such items are often called a cabinet. See Enclosure (electrical).

Junction boxes form an integral part of a circuit protection system where circuit integrity has to be provided, as for emergency lighting or emergency power lines, or the wiring between a nuclear reactor and a control room. In such an installation, the fireproofing around the incoming or outgoing cables must also be extended to cover the junction box to prevent short circuits inside the box during an accidental fire.[citation needed]

* Electrical junction box in the process of installation. Electrical conduits terminate at the sides and cables pass through or are joined inside the box.

* A metal junction box

* Australian Internal Surface Mounted Junction Box—showing wiring stages.

* Swedish junction box in Kuhlo-style with lever-connector Wago 221, where ground and neutral are connected in common.

## Solar panel

A PV junction box is attached to the back of the solar panel and it is its output interface.

## See also

* Cable tray
* Centrex
* Circuit integrity
* Distribution board
* Electric power distribution
* Electrical wiring
* Grounding
* Insulation
* IP Code
* Passive fire protection
* Pattress
* Solar micro-inverter

## References

1. ↑ "What is a Junction Box (Electrical Box)?". 25 February 2024. https://www.electricalknowledge.com/electricians-tools/junction-box/.

Back Junction Boxes

## External links

* NEMA: National Electrical Manufacturers Association
* IBEW: International Brotherhood of Electrical Workers
* NECA: National Electrical Contractors Association

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