What Is an Electrical Short?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon
A fuse. Fuses are designed to trip if there is a short circuit.
A fuse. Fuses are designed to trip if there is a short circuit.

An electrical short or a short circuit is a problem which occurs when an accidental path is created in a circuit, generating a connection where one did not exist before. Since electrical current follows the path of least resistance, it would follow this path rather than the one established in the circuit, causing an unusually high flow of current. Classically, shorts occur when bare wires cross, as for example when the insulation in an old outlet wears away, allowing wires to touch each other. People sometimes use the term “short” to refer to any problem with an electrical system, regardless as to whether or not it is a true electrical short.

Circuit breakers mitigate some of the danger associated with an electrical short.
Circuit breakers mitigate some of the danger associated with an electrical short.

Electrical shorts are very serious problems. The high rate of current results in the generation of heat, which can cause sparks or a fire. An electrical short often generates a distinctive popping noise when the circuit is activated, as the electricity follows the new connection it has discovered and the circuit is suddenly overloaded with energy. Smoke or flames may appear, and the short can be strong enough to melt insulation on electrical wiring, or to cause damage to the circuit itself.

An electrical short can cause sparks.
An electrical short can cause sparks.

In addition to being caused by worn insulation, an electrical short can also occur when a circuit is not wired properly, as for example when someone fails to notice that the metal lining of an electrical outlet is in contact with one of the wires. Shorts can also be created by damage. Storms often cause a plethora of electrical shorts which overwhelms the grid when trees and branches fall on power lines.

Unrepaired shorts can cause fires and severe damage, and it's usually cheaper to get an electrician out the minute a problem occurs rather than to wait for a fire to spark or for an electrical system to fail catastrophically.
Unrepaired shorts can cause fires and severe damage, and it's usually cheaper to get an electrician out the minute a problem occurs rather than to wait for a fire to spark or for an electrical system to fail catastrophically.

Circuit designers are well aware that shorts are a common hazard, whether one is making a lamp or laying out power lines. As a result, many circuits are equipped with overcurrent protection. Overcurrent protection detects an unusually high rate of current, and trips the circuit off to reduce the risk of damage. Many people have experienced tripped breakers or blown fuses as a result of overcurrent protection on household circuits.

An electrician can determine the cause of an electrical short.
An electrician can determine the cause of an electrical short.

When an electrical short occurs, it needs to be addressed. If someone is not comfortable working with electricity, an electrician can be called in to determine the cause of the short and repair it. Unrepaired shorts can cause fires and severe damage, and it's usually cheaper to get an electrician out the minute a problem occurs, rather than to wait for a fire to spark, or for an electrical system to fail catastrophically.

How To Find an Electrical Short With a Multimeter

Encountering a short circuit is not an uncommon occurrence when you are working with electricity. However, if you do not take the time to fix the problem, this could cause circuit board damage that ultimately leads to more serious and expensive repairs. The first step in this situation is to locate the origin of the issue. To do so, it is important to learn how to find an electrical short with a multimeter.

A multimeter is an instrument that provides electrical readings. Its handheld size makes it convenient to use for household measurements on most appliances and wiring systems.

With just a few basic steps, you will be able to safely and efficiently find an electrical short with a multimeter.

Always Begin With Safety First

Anytime you are working with electricity, every safety measure must be taken before you begin. For example, when you are attempting to find an electrical short, it is critical that you first power down your circuit. Proper precautions such as this will keep you and the people around you safe from injury. They also will keep your circuits and multimeter safe from damage.

Set and Test Your Multimeter

Once you have set your multimeter to resistance mode, the next step is to calibrate it so you receive consistent and accurate readings. You can calibrate your multimeter by simply touching the probes together. If your reading is zero, or close to zero, your multimeter is calibrated and ready.

There are newer multimeters that provide users with a built-in calibration feature. This function is helpful if your initial reading is not within 0.05 Ohms. All you have to do is keep touching the lead and ground tips together and, depending on the model, simultaneously press the button or turn the knob that is designated for calibration. Your multimeter is calibrated once it displays zero.

Narrow Your Search With the Multimeter

In order to narrow your search to find an electrical short, which will save you time and make your repair more manageable, focus only on circuit components with measurable resistance. How to find an electrical short then amounts to correctly using the multimeter's red and black probes. Keep the black probe in constant contact with the circuit's electrical ground and touch the red to the component you are assessing.

Inspect the Reading

Check the multimeter's measurement in resistance mode. If it shows a "1," then you have identified the electrical short. A short may also register as "OL," which means that the circuit's loop is open and the path is broken.

How To Tell if You Have an Electrical Short in Your Car

The complex electrical systems of newer vehicles on the road are intended to provide drivers with safety, convenience and luxury. When one of the components has an electrical short, however, all of that can quickly change to danger, inconvenience and frustration.

The first step before a repair is learning how to tell if you have an electrical short in your car. There are a few common symptoms to watch for:

  • You hear a clicking sound when you attempt to start the engine.
  • You smell burning rubber or plastic while operating the vehicle.
  • You see the check engine indicator appear every time you start the vehicle.
  • You notice that your headlights, brake lights and turn signals are dim, flickering or not working at all.
  • You experience power lock, power window, center display or other driving control failures.

How To Fix Electrical Short in House Ceiling Fixtures

House ceiling fixtures are just as susceptible to shorts as any other electrical system around a house. When this occurs, every component that is on that circuit is going to experience a power loss. Your first step to fix an electrical short in a house ceiling fixture is to safely locate it. Once you have done this, depending on the cause, the following steps will help you repair it:

  • Closely inspect the fixture to determine if the short was the result of a connection issue. If this is the case, simply tighten the loose or sagging wires.
  • Consolidate any stray wire strands that may have folded into another wire or a terminal screw. If the screw was burned in the process, it is important to replace it to avoid future conductivity issues from any resulting carbon deposits.
  • If you are able to rule out the fixture as the cause for the short, it may have occurred due to wire damage from heat exposure. If this is the case, it is often best practice to call a certified electrician to identify the location of the damaged wire and then professionally make the repair.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a HomeQuestionsAnswered researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a HomeQuestionsAnswered researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

anon999010

Overload protection does not protect against short circuits. Overcurrent protection does.

"What's the Difference?" you ask.

Overload protection protects equipment.

Overcurrent prtection protects people.

anon996421

I crossed two wires together accidentally. What should I do to get the lights back on and such?

anon336094

@Lonelygod: I just had this happen to me. It was arcing around the busbar of my breaker that was causing the fluctuations.

lonelygod

If you find the lights in your home flickering and dimming, as well as notice your power fluctuating, could an electrical short cause this?

I have noticed that our lights seem to dim quite a bit throughout the night, but occasionally go back to working at full power. It also seems to affect our modem and anything we have plugged in.

If it isn't an electrical short, what are some of the other things that could be causing this?

We would really like to get this fixed as it is bothersome and we worry there many be something potentially serious causing it.

wander

If you ever notice an electrical short in your house do not attempt to fix it yourself unless you have some electrical experience. Playing with an electrical short is an excellent way to get electrocuted.

I lived in an older house and some of the wires started sparking. We nearly had a fire, but managed to get someone in to fix it right away. My friend at the time was all gung-ho about trying to fix it himself, although we managed to keep him off the wires.

Our electrician told us that without the proper safety equipment our friend would have been probably hospitalized for touching the live wires.

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    • A fuse. Fuses are designed to trip if there is a short circuit.
      By: Willee Cole
      A fuse. Fuses are designed to trip if there is a short circuit.
    • Circuit breakers mitigate some of the danger associated with an electrical short.
      By: aNdreas Schindl
      Circuit breakers mitigate some of the danger associated with an electrical short.
    • An electrical short can cause sparks.
      By: Steven Love
      An electrical short can cause sparks.
    • Unrepaired shorts can cause fires and severe damage, and it's usually cheaper to get an electrician out the minute a problem occurs rather than to wait for a fire to spark or for an electrical system to fail catastrophically.
      By: Sudheer Sakthan
      Unrepaired shorts can cause fires and severe damage, and it's usually cheaper to get an electrician out the minute a problem occurs rather than to wait for a fire to spark or for an electrical system to fail catastrophically.
    • An electrician can determine the cause of an electrical short.
      By: Kadmy
      An electrician can determine the cause of an electrical short.