Old work electrical boxes have plastic tabs that tighten onto drywall after walls/ceilings are installed. New work electrical boxes have nails that are hammered into wooden joists/studs when these are exposed during new builds/renovations. Old work boxes can’t support heavy weights; new work boxes can.
Both old work and new work electrical boxes are designed to house wiring and act as a connection point between the ceiling/wall and a fixture or outlet.
Old work electrical boxes are installed when the studs/joists are not available; so after the walls and ceilings have been closed up. They are secured into holes in the drywall with plastic tabs that are tightened with screws.
New work electrical boxes are installed when the studs/joists are exposed; so typically when the initial construction of a home is being done. They are nailed into the studs/joists.
What Is an Old Work Electrical Box?
What Does It Look Like?
An old work electrical box is commonly constructed of plastic. Most often, but not always, the color of the plastic is blue.
There are also a few metal models for old work electrical boxes.
The shape of the electrical box is often rectangular to fit common outlets, light switches, and other electrical fixtures. They can also be circular for lighting purposes.
An important addition to this type of electrical box is the mechanisms that allow for installation.
On two corners of the box, or three areas of a circular electrical box (equally spaced to form an equilateral triangle), there will be screws. These screws don’t fasten into the drywall, though; they move mechanisms to secure the electrical box.
These mechanisms are plastic wings or clips that can be tightened by tightening the screws, and the tabs are what fasten the electrical box to the drywall.
When It Is Installed
Old work electrical boxes are meant for use during remodeling rather than for the initial building of walls or ceilings.
These additions are for when walls/ceilings are already closed up, and the studs/joists are not available to be used to attach an electrical box.
These kinds of electrical boxes do not have to be installed from the side like new work electrical boxes do (more on this later). Rather, they can be placed anywhere in a wall, as long as there is not a stud in the way.
Because the electrical box is being installed into a surface rather than onto a surface, drilling or nailing the box into the drywall is not possible or necessary.
How to Install an Old Work Electrical Box
For this process, you will need a variety of tools. The table below lists them all.
| Item | View on Amazon |
| Stud finder | View |
| Measuring tape | View |
| Straightedge | View |
| Utility knife | View |
| Screwdriver | View |
| Pencil | View |
| Level | View |
Put simply, the process for how old work electrical boxes are installed involves finding a place in the drywall with no studs/joists, making a tight-fitting hole for the electrical box, inserting the box, and tightening the screws so that the plastic clips can fasten the electrical box to the drywall securely.
The video below is a great, quick guide on how to install an old work electrical box. It also illustrates well how the plastic clips secure to the drywall.
Some tips that aren’t mentioned in this video but are still very important:
- Before running the live wire through your electrical box, it is very important that the circuit breaker for this wire is turned off (or the fuse is pulled out).
- For ease, it is best to cut the hole for the box, run the wire through the hole, run the wire through the box, and then install the electrical box. This is the easiest and most efficient way to go about installation.
Weight Ratings
The fact that old work electrical boxes do not have to be secured to a joist or stud means that there is a lot more flexibility as far as where the electrical box can be placed.
However, the downside of this is clear when heavy fixtures are involved.
When an electrical box is secured with plastic clips onto drywall, which isn’t nearly as strong as studs or joists, the electrical box’s fixtures must not be too heavy, or they will fall out.
Most sources agree that 50 lbs is the upper limit of most old work electrical boxes. However, the weight rating may vary by brand or material.
Some light fixtures and ceiling fans can weigh more than 50 lbs, which limits what can be attached to old work electrical boxes.
What Is a New Work Electrical Box?
What Does It Look Like?
Similar to old work electrical boxes, new work electrical boxes are often made of plastic, although some older models are made of metal.
They are often rectangular but also come in larger, circular shapes for light fixtures.
Rather than screws in the corners, new work electrical boxes come with nails, often two of them, through a small extension on the top and bottom of the electrical box, whether it is circular or rectangular.
Sometimes, these nails and their supports are parallel to each other, and sometimes they are angled slightly toward each other.
When It Is Installed
New work electrical boxes are meant for when a home is being initially constructed and the walls and ceiling are open and their studs and joists are able to be accessed.
They can also be used during renovations where the walls and ceiling are open and the studs and joists are accessible.
Rather than being installed into a surface and fastened to that surface, a new work electrical box is installed onto a surface and is, therefore, nailed onto it, rather than being clipped into it.
How to Install a New Work Electrical Box
To install a new work electrical box, all you’ll need is a hammer (amazon link).
The most important parts of installing a new work electrical box are:
- The box must be placed at a convenient height.
- The box must be placed on the stud/joist to allow its front edges to tie into the drywall.
After these specifications are achieved, use a hammer to attach the electrical box to the stud.
The video below shows this quick and easy process.
As is the case with old work electrical boxes, electrical safety must be upheld with live wires.
The video above mentions that your electrical box should be 12-16″ from the floor. Your hammer may fall within these dimensions and, as such, be a sufficient way to measure, but if it doesn’t, a tape measure is required.
In addition, knowing what appliances will be plugged into the outlet can make a difference to the required box height. A new work electrical box meant for a dryer outlet may have a different height need than an outlet for a mounted TV. K.
Something else that is important to know while preparing to install a new work electrical box is that they can often accommodate different wall thicknesses.
The raised plastic tabs on the box that are in contact with the front of the stud/joist can be adjusted further back on the box or further forward to accommodate a variety of wall/ceiling sizes.
Make sure to buy a new work electrical box with adjustable tabs to ensure that the electrical box fits flush.
Weight Ratings
Joists and studs, which are commonly confused, form the structural support for the ceiling and walls, respectively. Because of this, electrical boxes secured to them can hold more weight. In other words, they are able to have higher weight ratings than old work electrical boxes.
New work electrical boxes are able to support more than 50 lbs (but not all are designed to, so if you are installing a ceiling fan, make sure you get a ceiling fan-rated box).
Although the weight rating will vary by brand and material, it is likely that weights from 50-75 lbs will be able to be supported by new work electrical boxes.
Table of Differences Between Old Work and New Work Electrical Boxes
| Old Work Electrical Boxes | New Work Electrical Boxes |
| Can be installed even when active renovations or home-building are not occurring. | Can only be installed with active renovations or home-building allowing for walls and ceilings to be open. |
| The box attaches to drywall. | The box attaches to wood (joists or studs). |
| The box is attached with plastic tabs that are tightened with a screw. | The box is attached with two nails that are hammered into a joist or stud. |
| Can be installed anywhere with drywall and no studs. | Can be installed anywhere with studs or joists and only when the walls/ceilings are open. |
| Can only support weights of below 50 lbs. | Can support weights of above 50 lbs. |
Is One Better Than The Other?
Old Work Electrical Boxes Pros and Cons Table
| Pros | Cons |
| Can be installed anywhere without studs or joists. | Cannot support weights of more than 50 lbs. |
| The above means that light fixtures, outlets, etc., can be easily centered for aesthetic purposes. | Uses a variety of tools. |
| Active renovations or home construction do not need to be happening in order for the boxes to be installed. | Takes longer than new work electrical boxes to install. |
New Work Electrical Boxes Pros and Cons Table
| Pros | Cons |
| Only a hammer and measuring tape are needed for installation. | Can only be installed when walls and ceilings are open during renovations or new builds. |
| Only takes a few minutes to install. | Can only be installed on the side of joists or studs. |
| Can support more than 50 lbs. | It is more difficult to center fixtures, switches, and outlets as the studs or joists may not be in ideal locations. |
The question of which one is better mostly depends on the situation.
If you are building a home or if you are renovating, as long as the walls and ceilings are open, a new work electrical box can be installed.
The installation will be quick and will only require one or two tools, making a new work electrical box the most ideal in this situation.
However, if you are not building a home or renovating it, it will be very difficult to reach your joists and studs.
In this case, old work electrical boxes are ideal.
They may take a bit more time and tools to install, but if it means not opening up walls or having to wait until the next renovation, old work electrical boxes are definitely better.
Additionally, location and weight must be considered.
If the fixture is more than 50 lbs, an old work electrical box cannot be used safely.
If weight is not a problem but the electrical box needs to be in a very specific location, such as centered, an old work electrical box would be ideal since they have more of a range of where they can be located (you can also use a type of suspension bar).
Sources
https://carlonsales.com/techinfo/faqs/FAQ-ZipBoxes.pdf