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Painting your electric & gas meter box Professional

2 weeks ago   Freebies   Napier   42 views

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How to Size a Junction Box

Electricity powers the devices that make the modern world run, from refrigerators to TVs to industrial machinery. But getting that electricity correctly set up and distributed within homes and businesses requires a lot of special equipment. That equipment includes conduits, raceways and the devices that we’ll discuss in this article: junction boxes.

When an electrician creates splits and branches in wiring connections that run through cable raceways and conduits, they enclose the connection points within a junction box. A junction box provides protection for these sensitive connections against bad weather, accidental contact, tampering and other hazards that can damage wiring.

Below, we’ll talk about how to size a junction box appropriately and determine which attributes your junction box needs to have. Before we dive in, we’ll discuss some of the basics everyone should know about what a junction box is and how one works.

What Is a Junction Box?

A junction box is an electrical enclosure that protects electrical conductors at the points where they are spliced, tapped and pulled. These enclosures allow electricians to easily access the conductors to perform work when needed while simultaneously keeping the conductors safe from damage and unauthorized access.

Sometimes, you’ll hear the term “junction box” used to refer to an electrical fixture box. In the true technical definition of a junction box, wires should connect only to other wires and raceways. However, in practice, the term is also frequently used to refer to many other electrical box types in which wires connect to a fixture such as a ceiling fan, light switch or wall socket.

For more information on the various applications and designs of junction boxes, make sure to see our complete guide to junction box types.

Types of Feeder Pillars

Feeder pillar panels can come as custom manufactured or standard empty enclosures. Here are the most common electrical feeder pillars that are available:

Rail Feeder Pillars

Rail feeder pillars are non-conductive and are available in an outdoor location or station installments. It eliminates the risk of touch voltages in electrified rail areas. These pillars can have PADS approved Network Rail equipment such as:


DC Immune RCD

DNO Service Hands

Isolation Transformers

CT Chamber & Member

Cut-Outs & Isolators

LV Feeder Pillars

Low voltage feeder pillars (LV feeder pillars) are feeder pillar panels that operate at a “Low Voltage” (LV), where “Low Voltage” is defined by the International Electrotechnical Commission (IEC) as a supply system voltage in the range 50 to 1000 V AC or 120 to 1500 V DC (if you’re unsure of your operating voltage, you can easily check this with a good multimeter).

Electrical distribution pillars give LV power connections for single units or complex developments in the commercial and residential sectors.

LV feeder pillar is used for utility substation, M&E building services, hazardous area industries, and renewable energy. Highway pillars are used for CCTV, traffic signals, street lighting power, motorway communications, and control and distribution.

What is an SMC junction box?

SMC Junction Box is made from sheet moulding compound which ensure excellent dielectric properties.

These are available in two forms, one with inbuilt terminals and the other in plain format where the provision is there for attaching external terminal plate separately

While it is true that the junction box presents a neater means of concealing electrical junctions, the real value of the box is providing a degree of protection for the wiring interface at various junction points. It provides facility to connect two or more different size of cable.

Polycarbonate Enclosures Vs. Fiberglass Enclosures

The benefits of purchasing a polycarbonate enclosure instead of fiberglass can be found in the strength of the enclosure, its durability, and its modification possibilities. Polycarbonate enclosures can withstand over 900 pounds of impact, which is more than four times the impact resistance of fiberglass enclosures.

UV Light Resistance

When fiberglass enclosures are exposed to UV light, their color fades and the fibers are then exposed to direct UV rays which cause the material to “bloom” and deteriorate. In contrast, polycarbonate enclosures are manufactured as a solid piece using injection molding. Polycarbonate is a strong, durable material that withstands the harsh conditions of the outdoors and ultimately lasts longer than fiberglass enclosures. It is also used in car windshields and headlights, because unlike fiberglass, this highly durable plastic maintains its shape, color, and strength even when exposed to direct light.

Polycarbonate More Easily Modified than Fiberglass

One of the major differences between polycarbonate and fiberglass enclosures is their modifiability, which includes cutting holes or changing the material in some way. When modified, fiberglass enclosures give off a very fine dust that is irritant to the skin, can be dangerous to inhale, and is so fine it is hard to clean up. Instead of creating a fine dust, polycarbonate enclosures produce small curls of material that can be easily swept away and are not dangerous to touch or inhale. Because fiberglass is made up of interwoven fibers, the material is also more likely to splinter while modifying. Polycarbonate enclosures can be easily modified in the field using standard tools without being damaged or causing health concerns.


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