What is the difference between SLC and IDC?
What is the difference between SLC and IDC?

What does IDC mean in fire alarm?

initiating device circuit
Based on the type of detectors and FACU, the signals can be sent over an initiating device circuit (IDC) for conventional systems, or a signaling line circuit (SLC) for addressable systems.

What is SLC in fire alarm system?

SLC – Signal line circuits are initiating devices in an addressable fire alarm system. Notification devices notify in-building occupants about a problem. This is done by audible, visible, tactile, and textual devices.

What is IDC circuit?

◆ Initiating Device Circuits (IDC) ◆ A circuit where Automatic or Manual Initiating Devices are connected and the signal does NOT identify the individual device operated.

Can IDC wiring be T tapped?

The reason T-Tap wiring is allowed is because communications are being supervised to the device level. T-Tapping the different legs of the SLC provide multiple communications paths of the field devices and control equipment.

How does an SLC circuit work?

The Signaling Line Circuit or SLC in a fire alarm system is a power and computer style data bus. It is used to provide power to the computers inside each module and detector (each device), carry information from the panel to the devices, and carry information from each device to the panel.

How many fire alarm strobes on a circuit?

Most areas would have the cd set to 75 so the horn/strobes set to 75 would draw between 162 and 253mA or an average of just over 205mA. If you are in larger rooms and you have to have the higher settings then the mA is higher.

What is the difference between a Class A and Class B fire alarm system?

In fire alarm systems, the real difference between Class B and Class A is that if the pathway is interrupted, Class B only sends a "Failure Signal" to the panel, and Class A provides an extra path to get around the interruption.

What type of wire is used for fire alarm systems?

Only copper conductors can be used for fire alarm systems. You can use conductors of sizes 18 AWG and 16 AWG (installed in a raceway, enclosure, or listed cable) if they do not supply a load that exceeds the ampacities given in 402.5.

What kind of supervising station that is considered as recognized and most reliable?

central station
A central station is recognized as the most reliable type of supervising station.

What are the three methods of transmitting fire alarm signals?

From the moment a fire alarm signal activates until the time it's received and confirmed at the central monitoring station must take 90 seconds or less, according to NFPA 72. The three most common methods to transmit a fire alarm signal are telephone, cellular, and wireless mesh radio technology.

Does fire alarm cable need to be red?

No. Fire alarm wiring on a system designed to BS5839-1:2017 doesn't have to be red, but it does have to be a unique colour that is different to other types of electrical wiring within the building. Therefore, it is far more practical to wire fire alarms in red as it is industry practice.

Are two phone lines required for fire alarm system?

Reliability of the communications link Older versions of NFPA 72 require a customer to have two dedicated phone lines for commercial fire alarm systems. The idea behind this approach is that if one phone line should fail, the other likely would still be functional.

How do you test for a ground fault?

1:012:17What are Ground Faults? | Repair and Replace – YouTubeYouTube

How often should fire alarm cable be clipped?

BS5839 states all fixings used to secure fire performance cables must provide no less than the equivalent fire protection as provided by the cable itself. Ventcroft and many other manufacturers recommend a minimum fixing spacing of 300mm horizontally and 400mm vertical.

Can you still get a POTS line?

POTS lines (Plain Old Telephone Service) are the traditional phone lines that rely on physical copper wire for service. As the technology continues to age, the FCC has announced the mandatory termination of all POTS lines.

Does NFPA 72 allow for VoIP?

NFPA 72 now explicitly approves the use of alternative voice technologies (such as VoIP) and providers (such as cable) for fire alarm monitoring. All providers, including traditional telephone companies, must meet the same performance requirements.

What is the difference between short circuit and ground fault?

A short circuit is an abnormal connection between two nodes of an electric circuit intended to be at different voltages. It is caused when a “hot” conductor makes contact with a neutral or ground conductor. A ground fault is an accidental contact between an energized conductor and ground or equipment frame.

What happens if earth and neutral wires touch?

In Short if neutral wire touches a earth wire, An earth wire carrying load current is a risk of electric shock because a person touching this earth may present an alternative path for the load current and thus the risk of electric shock.

What happens if ground wire touches hot wire?

A ground fault occurs in residential circuitry when a hot wire contacts the ground wire or a grounded element, such as a metal box, and electricity then flows immediately to ground. A tremendous amount of current flows during a ground fault—enough to cause electrocution and fires.

What is the difference between earth fault and ground fault?

Earth fault is also a sort of ground fault. Whenever any live conductor detaches from its place and falls on the ground, the live phase does not get the solid ground, but the fault current flows because the earth's surface is conductive. In this condition, the fault current flows from the phase conductor to the ground.

What is the maximum distance allowed between cable supports?

Article 336-18 stated that cable must be secured in place at intervals not exceeding 4.5 feet (1.37 m) and within 12 inches (305 mm) from every cabinet, box, or fitting.

Does fire alarm cable have to be red?

BACKGROUND: It is widely assumed that wire, j-boxes, horns, strobes, annunciators, fire alarm control panels and other such equipment is required to be red in color. This isn't true. FACT: The only thing required to be the color red in commercial fire alarm systems by NFPA 72, is "the circuit disconnect means".

Why are POTS lines expensive?

As POTS subscriber levels decline, the costs of maintaining the existing infrastructure will fall on a smaller number of companies, which will lead to higher POTS service costs. There are also indications that the FCC may eventually phase out POTS services altogether due to unsustainable costs.

How much do POTS lines cost?

A POTS line is a business phone line. POTS lines are traditional analog phone service businesses use for voice, fax, DSL and alarm lines. A POTS line can cost anywhere from 20 to 60 dollars per month. Generally, a POTS line can cost anywhere from 20 to 60 dollars per month.

Is NFPA 72 a code or standard?

The NFPA 72 (National Fire Alarm and Signaling Code) is a standard published by the National Fire Protection Association every 3 years for installation of fire alarm systems and emergency communication systems in the United States.