Back to Basics: What Apprentices Really Need to Know About Testing Tamper Resistant Outlets

Apprentices, it’s no secret that there is a lot to learn. As an Electrical Training Alliance (ETA) partner, it’s our job and privilege to foster your growth. Not only are you tasked to learn the skills and technology needed to succeed in the electrical industry, you also need to know the National Electrical Code (NEC) and stay current with all its updates. Knowing the codes is just one piece of the job, we are here to help guide you to the right tools to successfully meet NEC standards and do it safely.
One of the latest updates to NEC was to increase the number of places where tamper-resistant receptacles must be installed. Article 406 of the NEC was expanded to require 15A and 20A, 125V and 250V tamper-resistant receptacles in dwelling units, hotel rooms, and child care facilities. In addition to homes and schools, structures such as dormitories, hospitals, and recreation facilities now require tamper-resistant protection.
These new requirements are primarily in place to protect children. We all remember back when we were growing up and items were pushed into wall outlets that should not have been. Tamper-resistant outlets have a mechanical safety shutter that keeps the terminal slots in the outlets covered. This makes it virtually impossible for anyone to accidentally or purposefully insert a foreign object, such as a paper clip or a small toy, into an outlet. Tamper resistant outlets allow access to power when the safety shutter is opened, which occurs when both prongs of an electrical plug enter at precisely at the same time.
With these increased regulations in place to provide a high level of safety, electricians are performing far more tamper-resistant receptacle installations than ever before. Which makes it critical to master how to safely test non-contact voltage (NCV) detectors when installing these receptacles.
Electricians have used NCV detectors for many years to verify when and where electrical power is on or off. These wonderful tools work by sensing the invisible electrostatic field that is around any conductor with AC voltage applied to it. As long as voltage is present, NCV detectors work even when electrical current is not flowing in the conductor being checked.
The tamper-resistant safety shutter makes the traditional single tipped NCV detector much less effective because it cannot enter the outlet slots. To detect power without using a dual-tipped NCV detector, users are left with one of two choices:
  1. Try to stick something else into the other slot to activate the shutter. This is very dangerous and should never be attempted!

  2. Try to detect the static field outside of the safety shutter on an outlet by using a less selective detector that is overly sensitive.
A detector that is overly sensitive will not accurately sort out hot conductors in an electrical box. Most, if not all, of the conductors will show up as being electrically hot. These detectors may not be selective enough to do the job. It is a compromise between being too sensitive and not being sensitive enough. While many electricians prefer to use a non-contact voltage detector that is automatically set, we recommend apprentices use a detector that has been set to be less-sensitive and then check the outlet slot with an insert tip detector. This process reinforces critical safety steps.
The best NCV detectors have their sensitivity optimized so they have good selectivity. They detect only electrostatic fields that are very close to the antenna used in their tip. This reduces the chances of a detector giving a “false alert.” A detector that