Circuit integrity is how little can a

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames a ...

affect an electrical circuit's operation. It is a form of

fire-resistance rating A fire-resistance rating typically means the duration for which a passive fire protection system can withstand a standard fire resistance test. This can be quantified simply as a measure of time, or it may entail other criteria, involving eviden ...

. Circuit integrity is achieved via

passive fire protection Passive fire protection (PFP) is components or systems of a building or structure that slows or impedes the spread of the effects of fire or smoke without system activation, and usually without movement. Examples of passive systems include floo ...

means, which are subject to

listing and approval use and compliance Listing and approval use and compliance is the practice of installing and operating safety-related products and materials in accordance with to minimum performance conformance testing requirements. The conformance could be for a certification list ...

. Alternatively, cable construction and materials can achieve fire-resistance ratings on their own such as

mineral-insulated copper-clad cable Mineral-insulated copper-clad cable is a variety of electrical cable made from copper conductors inside a copper sheath, insulated by inorganic magnesium oxide powder. The name is often abbreviated to MICC or MI cable, and colloquially known as ...

, or MI cable.

Fireproofing

Providing

fireproofing Fireproofing is rendering something (structures, materials, etc.) resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a ...

for cables,

cable tray In the electrical wiring of buildings, a cable tray system is used to support insulated electrical cables used for power distribution, control, and communication. Cable trays are used as an alternative to open wiring or electrical conduit syst ...

s, or electrical conduit, is meant to keep cables operational during a specified fire exposure and time, achieved by either: * Cable coating with a

fire retardant A fire retardant is a substance that is used to slow down or stop the spread of fire or reduce its intensity. This is commonly accomplished by chemical reactions that reduce the flammability of fuels or delay their combustion. Fire retardants m ...

lowers the spread of flame along the combustible cable jacketing. * An enclosure constructed of fire resistive materials.

Testing and certification

Testing in

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

is in accordance with ULC-S101 as required by the local

building code A building code (also building control or building regulations) is a set of rules that specify the standards for constructed objects such as buildings and non-building structures. Buildings must conform to the code to obtain planning permiss ...

. Inherently fire resistive cables can be tested to UL 2196, Tests for Fire Resistive Cables, whereas enclosures for cables that are not inherently fire resistive can be tested to UL 1724 or

USNRC The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...

Generic Letter 86-10, Supplement 1 in North America, or BS476 in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

or DIN4102 in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. For Petrochemical Industries, Offshore/ Onshore, API 2218 standards are referred as the fireproofing guidelines to address hydrocarbon fires which are more severe than the cellulosic fire profiles used in DIN 4102 and BS 476 part 20 test standards for buildings.

Shaft wall systems

Cables can be protected from fire by enclosing them in fire resistive "shaft wall" systems which are vertical and horizontal enclosures similar to ducts.

Current test methods

Germany has standardised testing via DIN4102 which encompasses both enclosures for cabling and bus ducts as well as inherently fire-resistive cables such as mineral insulated cables. North America testing includes UL1724 Standard for Tests of Thermal Barrier Systems for Electrical System Components and UL2196 Standard for Tests of Fire Resistive Cables.

Ampacity derating

If a cable is covered with a materiel which restricts heat transfer and therefore prevents it from cooling, the elevated temperature can reduce the allowable cable power capacity (i.e., less ampacity). Derating refers to the reduction of the ability of a cable to conduct electricity.

Cladding and wrapping considerations

The added weight of the wrap systems must be included in static and seismic calculations. Fireproofing of the hanging system must also be considered. Regular maintenance must be considered, as cladding and wraps are not load-bearing and can be damaged during normal building or facility operations.

Terminals and junction box considerations

The entire circuit must be completely protected including termination points and junction boxes.