Circuit Protection – Understanding How To Protect Your Domestic Wiring

How Important Is Circuit protection In Murrieta Homes?

Circuit Protection - Understanding How To Protect Your Domestic WiringCircuit protection is very important in modern electronic systems, to minimize system downtime and for safe operation. Circuit protection is one area of safety that needs to be taken extremely seriously. Individual units for the home circuit are usually rated at 15 or 20 amperes.

Proper circuit protection is of utmost importance not only for safety but also to avoid costly downtime and repairs to the system. Proper sizing of the circuit protection is the first step. The principals of the circuit are the same for AC and DC systems. Circuit protection is typically applied between the power supply and the control-circuit loads to protect the equipment on the control circuit, should a fault occur.

What is Circuit Protection all about

The purpose of circuit protection is to protect the wire from carrying more current than it is able. If the current becomes excessive the circuit protection should interrupt the circuit. If the current is not interrupted the wire can become hot enough to melt the insulation, and the result is often a short circuit with adjacent wires causing a meltdown and possibly a fire. The principals of circuit protection are the same for AC and DC systems.

The amount of current a wire can safely carry is determined by the size of the conductor, the temperature rating of the insulation, the ambient temperature and the number of wires in the bundle. On boats subject to ABYC standards the ambient temperature is taken to mean that wires located in the engine room are assumed to be 20 degrees warmer than elsewhere and their current carrying capacity is derated accordingly. Wires in bundles have their current carrying capacity derated because of the assumed ambient heat of the other wires. Boat cable normally has an insulation rating of 105 degrees C. See the table below for ampacity ratings.

Since the purpose of the circuit protection is to protect the wire the circuit protection needs to be as close to the source of power as possible. Any conductor between the source of power and the circuit protection is not covered. This is an important concept that is often misunderstood. The ABYC E.11 states that on DC circuits the circuit protection must be within 7” of the power source. It then goes on to list some exceptions for sheathed wires up to 72” and for pigtails less than 7” as well as for self limiting devices and starting motor conductors. Read more here.

Short protection is protection against excessive currents or current beyond the acceptable current rating of equipment and it operates instantly.


My introduction to circuit protection came at the tender age of eight. Being a curious lad with an inventive – and apparently self-destructive – bent, I decided to make my mother a lamp. I put a hose clamp around the base of a small light bulb, stripped the insulation off an old extension cord, and jammed both ends of the wires under the clamp.

When I plugged my invention into an outlet in the den, I saw the insulation flash off the cord just before the whole house went dark. Somehow the circuit breaker on the branch circuit failed and I tripped the main breaker on a 200 amp panel. My mother has never been anywhere near as impressed with this feat as I was, especially now that I know a little bit more about how electricity works and how close to I came to being a Darwin Award laureate.

Breaking It Off

What saved me that long-ago day was a circuit breaker. In its simplest form, a circuit breaker is just an electromechanical device designed to protect circuits by turning off the juice when the current flowing through it gets above the design point. Breakers need to sense the flow of current and turn it into mechanical action so that contacts can be physically separated quickly and safely. Check more here.

The Importance Of Reliable Circuit Protection

Circuit protection is a prime part of safety that includes fuse and circuit breakers which are deployed in various equipment in case of unexpected power fluctuations. Unlike the fuse box in most residential power centers, industrial circuit protection can rarely be reused after a short-circuit. For the first time, the circuit  can be integrated into to an RTU as seamlessly as the field devices providing the convenience of resetting or cycling the power to any of the components connected in the remote panel.

Circuit protection is a critical part of any industrial or commercial installation, to meet national codes and protect equipment and processes from the excess energy that could cause damage or safety issues, call us here: (951) 805-1262. While the basics of the electronic circuit are not new, electronic switches are a new technology for circuit protection. Two criteria developed for control protection are radial circuits where all conductors are contained within one cable (no large loops formed), and conductive sheaths of low resistance connected to the grounding grid at both ends.

Related Articles:
Examples Of Bad And Dangerous Electrical Wiring Systems
Electrical Terms For Circuits


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