When you need to run an electrical line from your home to another part of your property, a direct burial wire is required. Like anything involving electricity property-wise, however, there are code requirements and other variables you need to know about.
In this article, we’ll cover everything you need to know about direct burial wires — including installation tips if you plan to install them yourself.
Read on to learn more.
What Exactly Is a Direct Burial Wire?
A direct burial wire — also referred to as a direct burial cable — is a specific type of electrical wiring that’s designed to run underground. The official term for where a direct burial cable is buried underground is known as a trench, which should be deep enough so that once the cable is buried, it does not shift or breach the surface over time.
The material used for direct burial wires is typically a solid thermoplastic sheath that can seal out moisture and protect the conducting wires encased within. It’s the same concept as an electrical conduit (metal tubing), only there’s no metal. This is important, as metal is vulnerable to rust and corrosion from excessive moisture — which you don’t want coming into contact with your underground wiring.
Why Choose Direct Burial Cables
Several other types of power lines can be used to run the electricity throughout your property. You’re probably most familiar with SE or SEU lines — both of which are commonly used to provide electrical services throughout the grounds of commercial and residential buildings.
However, direct burial wires have the advantage over all the other types of wiring due to their underground installment. This makes them storm and hazard-proof. Aside from being designed to withstand an underground environment and extreme weather events, direct burial cables also:
- Are crush-resistant
- Are water-absorption-resistant
- Can withstand the effects of various temperatures
- Are usually enhanced with a special type of armor to protect them from digging and gnawing rodents
Of course, this also makes them more expensive to install.
The Different Types of Direct Burial Wires
There are two common types of direct burial cables used in residential areas:
- Underground service entrance (USE)
- Underground feeder (UF)
USE cables are typically black and are most often used for bringing power from a utility’s transformers into an individual house. USE cables are rarely installed by homeowners as they’re usually handled by utility professionals.
UF cables are typically gray and come in rolls resembling non-metallic (NM) sheathed cables. Unlike your standard NM cable — which is rated for dry interior applications only — UF cables are rated for outdoor use as well as indoor use. For example, if you wanted to install electrical wiring between your home and an outdoor lamp post, the UF cable is the direct burial wire type you would choose.
Additionally, unlike standard NM cables, UF cable wires are completely and individually encased in a solid plastic material. This protects each wire from the others while preventing moisture or other elements from seeping into the cable and destroying the wires. It’s also UV-resistant in case parts of the cable won’t be buried in a trench.
When to Use a Direct Burial Wire
Direct burial wires have several applications, including (but not limited to):
- Running electricity to and from the home
- Tracer wire installations for underground utilities
- Running electricity for pet fencing
- Phone and other telecommunications
- Fiber optics
- Irrigation
- EV charging stations
It should be noted that different types of direct burial cables will be buried at different depths based on their application. Smaller and lower voltage wires, such as that used for pet fencing, are only buried a few inches below the surface. Larger gauge cables, such as those used for underground utilities, are buried much deeper to prevent potential damage caused by construction or digging.
As for as homeownership goes, direct burial wires would also be used for things like installing sprinkler systems, connecting lamps or post lights, and so on. More importantly, all direct burial wires used for residential applications must comply with local municipality regulations to ensure a safe installation.
Tips for Installing a Direct Burial Wire
If you plan to install a direct burial wire yourself, your two biggest concerns are digging and getting in touch with your local building inspection department to see if an electrical permit is required. You’ll also need to inquire about the specific requirements regarding trench depth.
If an electrical permit is required, you’ll need to fill out the proper paperwork and pay the associated fees. Once the job is almost done, you’ll also need an electrical inspector to verify the depth of your trench and direct burial cables before they can be covered.
From there, you’ll want to keep the following in mind:
- Always bury UF cables 18 inches deep. If you’re using a PVC conduit, you’ll likely need to dig a deeper trench up to 24 inches — but it all depends on the local requirements for your project.
- Call the national Call Before You Dig Hotline (8-1-1) at least seven days before starting your project. This is necessary to alert all the utilities with service lines in your area so a representative can come out and mark the lines on your property so you know where not to dig.
- If you’re running a long-distance direct burial wire, you’ll need to calculate the voltage drop to determine whether you need to use a larger cable to minimize the voltage loss you may experience over long runs.
- It’s a good idea to create a map of your property outlining where your underground wiring was installed. You can use it as a reference point for future projects and to guide you or a professional to exact cable locations should you need to make repairs.
Get Your Direct Burial Lines Installed By the Professionals
Direct burial lines are used for all sorts of electrical projects on residential properties. While installing a direct burial cable may seem easy enough, it’s a job that’s best left up to experienced electricians.
Get in touch with Minneapolis’s most experienced electricians today for a free consultation!
