I moved into a house with a GE PowerMark Plus Load Center. I'm trying to add some AFCI and GFCI breakers. The label on the inside of the door states that the following GE breakers can be used: THQP, THHQP, THQL, THHQL, TQDL, THQDL, or TXQL. I know that THQL is wider than THQP, but other than that I'm not sure what the rest mean. Which one would I use for AFCI, GFCI, or combo breakers? I included a picture of the label.
GE breaker part numbering explained
GE loadcenter-type breakers come in various flavors, but there are a few things in common. First off, all the part numbers start with "T" -- this is likely because the line was acquired when GE picked up an upstart breaker maker called Trumbull Electric. The next one or two letters (H, HH, X) designate the interrupting rating of the breaker -- the normal H designates a standard residential 10kAIC breaker, with a few exceptions to be noted below, while HH and X are used for higher interrupting ratings found in commercial work. Some very old (Trumbull-era) breakers lack this letter in their part number, indicating they are only rated to 5kAIC -- this is a good indication they are obsolete. The next two (or occasionally three) letters indicate the type of breaker:
- QL denotes the standard "Q-line", plug-on-type, 1" wide breaker
- QD denotes a "double-wide" (4 slots in a 2x2 pattern) breaker used for 150-225A ratings -- these breakers are 10kAIC unless denoted with a raised interrupting rating by a single H in the part number. They are cable-in/cable-out types by default, although they are available as plug-on types as well, denoted by a "QDL" in the part number.
- QP denotes a "half-width" (1/2" wide), plug-on-type breaker (GE's equivalent to what's called a "double-stuff", "cheater", or "tandem" breaker). These can only be used in slots that specifically permit them.
- QC denotes a cable-in/cable-out type of breaker, used for applications like subdivided protection for large electric heating loads. Instead of plugging into a panel to get their power, they have a lug terminal on each end and thus can be used in a situation where there is no busbar to plug on to.
Following this letter prefix for the breaker type/series (what you see on the labeling on your loadcenter), there is 4 or 5 digit part number:
- The first digit denotes the number of breaker poles present
- The second digit denotes the voltage rating of the breaker, save for THQP's which lack it and are always 120/240V as a result. It will always be 1 on breakers used in residential work, for a 120/240V slash rated breaker (120V line-to-neutral, 240V line-to-line).
- A few devices will have letters after the second digit, to denote unprotected switching -- you probably won't run into these.
- The remaining digits in the part number specify the trip rating (amp rating) of the breaker.
Any designations after the amp rating indicate special breaker features, such as ground fault, arc fault, or dual function (arc & ground fault) protection. (There are others as well, but you generally won't find them in residential work.)
- GFT denotes a current-generation ground fault breaker (the T here is for self-test functionality as per the current UL943)
- AF2 denotes a current-generation combination arc fault breaker (AF was used for the previous generation of GE combination arc fault breakers -- the differences are fairly subtle and only impact multi-wire or 240VAC branch circuits)
- DF denotes dual-function breakers that combine arc & ground fault protection
Of course, not all part numbers are made -- check a current GE breaker catalog for details on what you can get.
I put two GFCI breakers in my 47-year-old GE panel. One of the GFCI breakers I got was THQL1120GF (so 20 A) and one was similiar but 15 A. These are not combination AFCI.
These are 1" wide so you would have to put them where the panel instructions allow and if you have a 1/2" wide breaker in the slot you want to use, then you might have to rearrange the breakers to make a full 1" available. All of my 120-V breakers were 1/2" and the panel was nearly full so I had to shift breakers to fit in the 1" GFCI breakers.
My panel is now full so if I want to provide AFCI protection I will have to use AFCI receptacles for the bedrooms.