Improper wiring of receptacle triggers electric shock

Incident Investigation

Improper wiring of receptacle triggers electric shock

December 1, 2016


Reference Number:


Incident overview

An occupant received an electrical shock while plugging in a cell phone charger to a receptacle in the bedroom of a house. The shock was described as minor by the occupant and no medical treatment was received.

Regulated industry sector

Low voltage electrical system (30V to 750V)



Investigation conclusions

Site, system and components

Receptacles are required to be secured to the outlet boxes that they are connected to and wiring entering outlet boxes is required to be properly installed. This is required to provide support for the receptacle when plugging in and unplugging cords, to enclose the energized terminals and conductors so they are not damaged or contacted, and to contain thermal energy if the wiring, connections, or receptacle fails. Receptacles that are not properly secured to outlet boxes and do not have cover plates installed are subject to accidental contact by persons and objects and present a shock and fire hazard.

Failure scenario(s)

A 15 amp 120 volt rated receptacle in a house was not secured to the outlet box that it was connected to. When plugging in and unplugging a cell phone charger the occupant of the house was holding onto the receptacle with one hand and plugging in the charger with the other. The receptacle connection terminals were exposed at the sides of the receptacle. When the occupant held onto the receptacle he contacted the energized terminal and the neutral or bonding terminals located on opposite sides of the receptacle. He received a 120V shock to his hand which made him quickly pull his hand away from the receptacle.

Facts and evidence

Interview with the person that reported the incident indicated the following:
- Her son in-law was shocked while plugging his cell phone charger into a receptacle.
- The receptacle in his bedroom was not fastened to the outlet box and was hanging from the wiring.
- The owner of the house was contacted and he came to the house but did not fix it properly. The receptacle was still not secured to the outlet box and was hanging from the wiring.
- She had concerns about other issues with the electrical system in the house that she and her family are renting.

Interview with the person that received the shock indicated the following:
- He received a shock the first time in early December of 2016 shortly after they moved into the house.
- He received the shock while holding onto the receptacle with one hand and plugging his cell phone charger in with the other hand.
- The receptacle was not secured to the outlet box and the connection terminals on the side of the receptacle were exposed.
- After the incident the owner was notified and came and put some tape around the receptacle but did not secure the receptacle to the outlet box.
- He received another shock in January of 2017.
- He installed additional electrical tape around the receptacle himself which prevented him from getting shocked again.
- He indicated that during the shock he experienced discomfort but he did not require medical attention and was not permanently injured.
Interview with the owner of the house indicated the following:
- He has owned the house for approximately 13 -14 years.
- He was aware of the incident.
- Over the years he has had some wiring fixed and added to the house because it is very old.
- He was aware that there was some unsafe wiring in the house and had intended to get it fixed but had not got around to it yet. Observations of the receptacle, outlet box, and wiring after the incident:
- The 15A 120V receptacle located in the upper floor bedroom was not secured to the outlet box.
- Electrical tape had been wrapped around the side of the receptacle to cover the exposed energized terminals.
- A non-metallic sheathed cable was improperly entered into the outlet box near the front edge at the bottom of the box. This improper wiring installation may have impeded efforts to install the receptacle onto the box because of its location.
- Inspection of the house’s electrical system identified multiple unsafe and noncompliant items.


  • Injury
    • Qty injuries: 1
    • Injury description: An occupant of a house received an electrical shock.
    • Injury rating: Minor
  • Damage
    • Damage description: n/a
    • Damage rating: None

Incident rating


1496.61 KB