Finally, a USB GFCI Receptacle is Here!

Standard receptacles with built-in USB ports are not new to the market. In fact, you can find these types of receptacles in airports, schools, hotel rooms, and in residences. These devices allow you to use both of the 120v plug-in portions of the receptacle for something other than a charging brick. However, GFCI devices with built-in USB ports are something new to the electrical world. They were developed for the same reason as the standard receptacle with a USB port, but in locations that require GFCI protection

There are several differences between USB-A and USB-C. USB-A is the standard thin square-shaped port that has been around for years. The USB-C is a newer style that is becoming much more popular as of late. It is smaller in size at a glance but the USB-C is capable of much higher power delivery than its predecessor, which results in faster charging capabilities and the ability to power larger devices. Many of the larger tech companies are moving over to the USB-C in the manufacturing of their products. USB-C is capable of being backward compatible with USB-A via an adapter. By having the USB-A and USB-C ports integral to the device, it allows for both of the 120v plugs on the device to be used for something other than a charging brick.

GFCI devices work on the principle of sensing the imbalance of current flowing from the hot and neutral. Any difference of 4-5 milliamps will result in the device opening the circuit stopping the current flow in a fraction of a second. So in essence, if the GFCI device senses a difference in current from what is going out on the hot wire from what is coming back on the neutral wire, the device will trip. Anything more than 4-5 milliamps difference could result in harm to the average person and anything less than 4-5 milliamps could result in nuisance tripping of the device. 

We have all been there. Undoing the screws on an existing device that someone else has installed in an attempt to replace it, only to find the wires are barely long enough to let the device come out of the box! Article 300.14 of the 2020 NEC tells us that we are to have at least 6 inches of free conductor at each splice, junction, device or switch, measured from the point the wire emerges from its raceway or sheath. The keyword here to focus on is where the conductors exit either the raceway or sheath. Many electricians misinterpret it to measure from either the back of the box (which can result in leaving you less than the required amount) or from the front of the box/face of drywall (which can result in too much wire therefore resulting in more conductor to deal with when folding cable back in the box). The code reference also states that where the opening to an outlet, junction or switch point is less than 8 inches in any dimension that each conductor shall be long enough to extend at least 3 inches outside of the opening. 

This rule is there so that the next electrician that needs to service that device has enough slack to easily pull the device out of the box, undo the existing terminations and re-terminate a new device, or, at least be able to pull the device out of the box to troubleshoot it. A good rule of thumb (no pun intended!) is to keep the conductors in your fist, with the back of your fist touching the box, extend your thumb out (like giving a horizontal thumbs up) and cut the wires at the end of your thumb

There is an order in which we should place the terminated wires back within a junction or device box and shouldn’t be just placed randomly. The grounding conductors should be spliced first and neatly folded in first so they are in the back of the box. The neutral conductors should then be spliced next and placed neatly into the box, followed by the hot conductors last. The reason for this sequence and wire placement is so that the particular run you are working on will be grounded first, then the return path (neutral conductor) and finally the hot wires will be hooked up, resulting in having a reasonable safety net of a complete alternate return path should something not go as planned.

GFCI receptacles have a unique function that differs from a normal receptacle, in that it is capable of providing GFCI protection for not only itself, but that of additional receptacles downstream of it. This is accomplished by utilizing both the Line and the Load portion of the wiring terminals. These terminals are differentiated and identified on the back of the GFCI device. You would splice your grounding conductors together as with any device and terminate the grounding conductor to the green grounding screw on the device. Your incoming (from the panel or whatever is providing power to the GFCI device) wires will be terminated on the respective Line terminals (one for the hot conductor and one for the neutral conductor) and the wires leaving the box going to the next receptacles in line would be terminated on the respective Load terminals (again, one for the hot conductor and one for the neutral conductor). This allows a single GFCI device, placed upstream of one or more additional standard receptacles, to provide GFCI protection at those points as if a GFCI receptacle were there. This dramatically reduces costs and installation time.

Using a meter to find line and load wires is something that must be done to identify which is the incoming set of wires (from the panel or whatever is supplying power to the device) from the other wires leaving the box going to the next device downstream. If the wrong set of wires is installed on the wrong terminals of the GFCI device, you run the risk of the GFCI not operating properly and potentially presenting a health/safety hazard. The easiest and most straightforward option to identify which is which would be to first de-energize the circuit and remove the existing device, keeping the individual Non Metallic Sheathed Cables separate. Once the device is removed and the separate NM cables identified, you can reapply power to the circuit. When you place the leads of your meter on the wires using the voltage function, the set of wires that shows as being energized are your line side wires, the other set would be your load side.

Where not using the feed through option of protecting the receptacles downstream of the GFCI receptacle, we would either need to splice the ungrounded conductors together, the grounded conductors together, and the grounding conductors together, leaving a pigtail at each to terminate to the device. Or, if the GFCI we are installing has only a single set of wires, terminate those wires straight to the device. If using wire connectors for splicing, Article 110.14 (B) applies. It states:  Splices-“Conductors shall be spliced or joined with splicing devices identified for the use or by brazing, welding or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined so as to be mechanically and electrically secure without solder and then be soldered. All splices and joints and the free ends of conductors shall be covered with an insulation equivalent to that of the conductors or with an identified insulating device.

There are wire connectors made specifically for grounding. It looks much like a standard wire nut, but at the closed end, there is a hole for you to put one of the grounding conductors through it to connect to your device. When making the splice with this type of wire connector, in lieu of cutting ALL of your grounding conductors to the same length and twisting them together with the connector, you leave one of them longer than the rest. As you are installing the wire connector, feed the longer conductor through the hole and then twist as normal. Then, just install that longer wire to your grounding terminal of the device.

There are also wire connectors with a pigtail already built in for tailing out to your device. Again, they install much like a standard wire connector, but at the closed end there is a 6” long or so piece of wire preinstalled. This wire is connected to the metal spring type fastener inside the wire connector under the plastic cap. As you would twist together your wires and install the connector as normal, you now are left with a pigtail you can install onto your device. Using one of these wire connectors saves you a step of having to cut the pigtail and prep it for install.

Nuisance Tripping is a term to describe a GFCI device that trips and needs to be reset more often than it should. For example if you had an old toaster in your kitchen that you had plugged in that was more toward the end of its service life, some of the inevitable voltage bleed off associated with an older appliance, would be recognized by the GFCI device as having an issue somewhere in the circuit and would trip. A homeowner (or electrician) would reset the device only to have the GFCI trip again next time the device was used. In previous years this was a common problem, but as technologies have advanced, the devices themselves have been refined to reduce the issue. 

Screwless Plates are a nice addition to a device replacement as they look much more streamlined without any faceplate screws visible after the installation. Installation instructions differ from manufacturer to manufacturer, but usually have an additional mounting plate that is installed when the device itself is screwed into the box. Then the screwless plate either snaps onto that plate or slides down from above. As a suggestion, one should at least purchase all of the plates for a single room (if not the whole house or job) so that the styles and colors match. Different manufacturers plates will most certainly look a bit different, and slightly varying color runs can happen if plates are purchased months apart.