CDL Hours of Service (HOS): Complete Guide to ELD Mandates

Hours of Service (HOS) rules are the most heavily enforced federal regulations in the trucking industry. Violate them and you face fines, being placed out of service, or losing your CDL. The rules exist for one reason: fatigue is a leading cause of commercial vehicle accidents. This guide covers every HOS rule you need for the CDL written test and for your daily driving. Practice with our free CDL practice tests.

The Four HOS Limits You Must Know

There are four daily/weekly limits that govern how long you can drive. You must comply with all four simultaneously. Violating any one of them puts you out of compliance.

1. The 11-Hour Driving Limit

You may drive a maximum of 11 hours after 10 consecutive hours off duty. Once you hit 11 hours of driving, you must stop and take 10 consecutive hours off duty before driving again. Note that "driving" means actually operating the vehicle — on-duty time that doesn't involve driving (fueling, loading, inspections) doesn't count against the 11-hour limit, but it does count against the 14-hour window.

2. The 14-Hour Work Window

After coming on duty, you have a 14-hour window in which all driving must be completed. The 14-hour clock starts the moment you begin any work — including pre-trip inspection, loading, or paperwork — and it does not stop for breaks, meals, or fuel stops. Only off-duty time or sleeper berth time can pause the 14-hour clock. After 14 hours, you cannot drive (but you can do non-driving work like loading or paperwork).

Example: You come on duty at 6:00 AM. Your 14-hour window ends at 8:00 PM. Even if you've only driven 8 of your 11 hours, you cannot drive after 8:00 PM without taking 10 hours off duty.

3. The 30-Minute Break Rule

For property-carrying drivers, if you have driven 8 hours without a 30-minute break, you must take a 30-minute off-duty or sleeper-berth break before driving again. The break can be taken as 30 consecutive minutes off duty, 30 consecutive minutes in the sleeper berth, or a combination (e.g., 15 minutes off duty + 15 minutes sleeper). Passenger-carrying drivers (bus drivers) are exempt from this rule.

4. The 60/70-Hour Weekly Limit

There are two weekly limits depending on your carrier's operation schedule:

• 70-hour limit (7-day operation): If your carrier operates 7 days a week, you may not drive after accumulating 70 hours on duty in any 8 consecutive days.
• 60-hour limit (6-day operation): If your carrier operates 6 days a week, you may not drive after accumulating 60 hours on duty in any 7 consecutive days.

To track this, use the look-back method: add up all on-duty time for the past 7 or 8 days. If the total is at the limit, you cannot drive until enough hours "fall off" the back end of the window.

The 34-Hour Restart

If you reach your 60/70-hour limit, you can reset your weekly hours by taking 34 consecutive hours off duty. This is called the 34-hour restart. After 34+ hours off, your 7- or 8-day window starts fresh with zero hours.

Rules for the 34-hour restart:

• Must be 34 consecutive hours off duty or in the sleeper berth
• Must include two periods from 1:00 AM to 5:00 AM (for property carriers)
• You can only use one restart per 168-hour (7-day) period
• The restart is optional — you don't have to use it if you have enough hours under the look-back rule

Sleeper Berth Provision (Split Rest)

The sleeper berth provision allows you to split your required 10-hour off-duty period into two parts. This gives drivers flexibility to take breaks during the day and extend their work window. The split must be:

• At least 8 consecutive hours in the sleeper berth, plus
• At least 2 consecutive hours either off duty, in the sleeper berth, or a combination
• The two periods must total at least 10 hours

The 8-hour sleeper period pauses the 14-hour clock. The 2-hour period does not pause the 14-hour clock but does count toward your 10-hour off-duty requirement. This provision is especially useful for team drivers and for managing your schedule around traffic or delivery windows.

The ELD Mandate

Since December 18, 2017, the FMCSA requires most commercial drivers to use an Electronic Logging Device (ELD) to record Hours of Service. The ELD automatically records engine hours, vehicle movement, miles driven, and location. Key facts:

• ELDs connect to the vehicle's engine to automatically record driving time
• Drivers must still log in, select their duty status (on duty, off duty, sleeper berth), and certify their logs
• ELDs are not GPS trackers — they record location at duty status changes, not continuously (though some carriers add tracking)
• Exemptions: Short-haul drivers (within 150 air miles), drivers of vehicles manufactured before 2000, and some agricultural haulers are exempt
• Violations: Falsifying ELD records is a federal offense. Carriers can face fines of $1,000+ per violation, and drivers can be placed out of service

Common HOS Violations

HOS Exemptions to Know for the Test

• Short-haul exemption: Drivers operating within 150 air miles who return to the same location within 12 hours don't need an ELD or logbook
• Adverse driving conditions: You may extend your driving time by up to 2 hours if weather or road conditions unexpectedly delay you (but you must still comply with the 14-hour window for property carriers)
• Emergency exemptions: During declared emergencies, HOS rules may be temporarily waived
• Personal conveyance: You can drive the truck off duty for personal use, but only if the vehicle is unladen (no trailer or cargo) and you're not advancing a load
• Loading/unloading: Time spent loading or unloading is on-duty time, not driving time — but it counts against your 14-hour window

Frequently Asked Questions