Buried beneath flowerbeds, driveways and open lawn is a network of electric, gas, cable and sewer lines that’s easy to take for granted. But every three minutes, someone strikes a utility line while digging.

Hitting a buried electric line puts you at serious risk for electrocution and could leave you and your neighbors without power for days. Natural gas lines can be even scarier — a struck pipe can cause a serious gas leak, sometimes requiring evacuation, or even cause an explosion if the shovel sparks when it hits the metal pipe.

Related: What To Do If You Smell Gas

But you don’t need to strike a utility line to face serious consequences. The law now requires residents of all 50 states to dial 811 before digging to reach the national Call Before You Dig hotline. It’ll route your call to your local utility company, which will come to your house within a few days to mark the locations of buried lines.

While the call is required nationally, the rules and penalties vary. In Washington state, for example, you can face fines of $1,000 or spend up to 30 days in jail, just for digging deeper than 12 inches. If in the process you hit a line, the fine could balloon to $10,000. Plus you could be on the hook for triple the cost to repair the damage. Read on to see why it’s so important to make the call before you dig.

Closer than you think

It’s a no-brainer to have your contractor call before big projects like adding an in-ground pool. But for less ambitious projects you tackle yourself — building a deck, or digging out a garden bed — it may not occur to you to need permission.

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The thing is, many utility lines run only a few inches beneath the soil. That’s why you need to check before you so much as dig down to install a pole for a mailbox. The law requires you to make the call before a shovel or piece of excavation equipment ever touches the earth. And while most states require the person performing the work to place the call, don’t assume your contractor actually did. Pennsylvania One Call suggests requesting the ticket number from your contractor and calling 811 yourself to confirm that a markout was requested and performed before work is started.

What you may not know can hurt you

Even if you’ve lived in your house for years, don’t assume you know about everything that’s lurking beneath the soil. Previous owners may have run outdoor water or power lines, or buried an underground storage tank for propane or heating oil. While your local utility provider may only be able to locate active municipal lines, many states including New York will refer you to excavation or surveying companies with the ability to help you find everything else.

Dig with care

Once the lines are marked, you still need to proceed with caution. Check with your state’s call center to see how far you should stay from markings. If you’re planning a big project that requires the use of excavation equipment, you or your contractor may need to use a hand shovel to dig in areas close to marked lines.

And since professional locators rarely indicate the depth of buried lines, many states recommend leaving 24 inches on either side of the mark if your project permits, though you may be allowed to dig with care using small hand tools. 

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Paul Hope, a trained chef and DIY enthusiast, has restored two houses and writes about food and homes.