No power to outlets, flickering lights, or an intermittent loss of power are usually attributed to a loose wire connection if the circuit breakers are working properly. A loose wire connection can cause the wire to overheat, eventually causing the connection to fail. Sometimes a loose connection will make a crackling noise. A loose wire connection could happen in any of these places:

Wire connection to circuit breaker or neutral bar inside electrical panel.
Loose wire makeup, loose connection to switch, light fixture, or outlet inside of electrical box.
Loose wire connection on power company transformer or equipment.

Troubleshoot Outlets

No Power to Outlets or Lights

Troubleshoot No Power to Outlets or Lights

Loose Wire Connection

Finding a loose wire connection requires the power to be turned off in all situations. Loss of power to one device can be easy to find, loss of power to one or more circuits can be very time consuming. Here are the steps that can be taken to find a loose wire connection.

A loose wire connection can happen during initial construction or when a modification is made to the electrical system (adding a ceiling fan, or replacing a switch, light fixture, or outlet). After the electrical panel is inspected by a qualified electrician, finding a loose wire connection in part of a circuit, or more than one circuit may take a lot of time.

The process of finding a loose wire connection can vary with the specific symptoms of loss of power including:

No power to one device (switch or outlet)
Whole or part of a circuit
Two circuits
The whole house

Turning off Power

Before trying to find a loose wire connection, power needs to be turned off to three or more circuit breakers. In a Multi-Wire Branch Circuit, one neutral wire may supply return current from two different circuits. If one circuit breaker is turned off in a multi-wire branch circuit, and a neutral connection is opened, a shock could occur (see Open Neutral). When turning off the circuit breaker for a circuit, the breaker above and below this breaker also needs to be turned off.

No Power at One Device

Circuit breaker to affected circuit is turned off and verified that it is turned off at each device.
The cover of the device (switch, outlet, or ceiling light fixture or fan) is removed and the device is pulled out to access the wire connections.
Wire connections to devices are tightened (if necessary).
Wire connectors may need to be removed to inspect for proper alignment of stripped wire ends. Wire connectors should be screwed clockwise until the connector stops twisting. See How to Install a Wire Connector.

Troubleshooting Electrical Panels

Troubleshooting electrical panels and circuit breakers should be done only by a qualified electrician.

When an electrician is troubleshooting a loose connection inside an electrical panel, the main circuit breaker that feeds the panel must be turned off. Removing the cover of a live electrical panel poses a risk of serious electrocution and arc flash. After removing the cover and verifying that power is off, all of the circuit breaker wire connections are checked for proper tightness along with main feeder connections and the neutral and ground bus bars.

Align stripped wires

No Power on One or Two Circuits

Circuit breaker to affected circuit(s) is turned off and verified that it is turned off at each device.
Repeat steps 2 - 4 above on all affected devices.

No Power to Whole House

When there are flickering lights or intermittent loss of power to the whole house, and the electrical panel has been inspected by an electrician, call the power company about the problem. There may be a loose connection at the power company transformer.

Troubleshoot Outlets