Fluke 117 vs Fluke 115

Specs side by side

Specs checked against manufacturer documentation and official Amazon listings. Both products hands-on tested by OhmSavvy. How we research.

Key differences

• →Only the 117 has VoltAlert: a sensor in the top of the meter that lights a red LED and beeps near an energized AC conductor, with no probe contact.
• →Only the 117 has a low-impedance input. On its AutoVolt position the input drops to about 3 kΩ, so capacitively coupled ghost voltage collapses instead of showing as a believable reading.
• →Only the 117 has AutoVolt, which picks AC or DC from the signal itself. On the 115 you choose the AC or DC volts position yourself.
• →Everything else matches on Fluke's datasheet: voltage and current ranges and accuracy, resistance to 40 MΩ, continuity, diode test, capacitance, frequency, Min/Max/Avg, backlight, size, weight, battery life and warranty.
• →Neither measures temperature or has a mA or µA range; in the 110 Series those belong to the Fluke 116.

At a glance

Both meters carry our Hands-on Tested badge and a 4.8 rating. Every spec below comes from Fluke's own product pages, the 114/115/116/117 datasheet and the 2020 users manual. For the full write-ups, read our Fluke 117 review and Fluke 115 review.

Fluke 117 vs 115 spec by spec

Fluke publishes one accuracy table for the whole 110 Series and marks which model has which function. Read down the last column: of more than twenty lines, three differ, and all three are things the 117 adds.

Size, weight and battery life give nothing to chart: Fluke lists the same 167 × 84 × 46 mm case, 550 g and 400-hour typical battery life for both. The numbers that do differ are the input impedance above and the accuracy you trade for AutoVolt's convenience below.

How LoZ drains ghost voltage

A disconnected conductor running beside a live one picks up voltage through the stray capacitance between them. That coupling can push only a tiny current, but a meter with a 5 MΩ input barely loads it, so the display shows a large, believable number on a wire that can't power anything. This is the classic open neutral or abandoned-run trap. The 117's AutoVolt position drops the input to about 3 kΩ, which drains the coupled charge so a phantom reading collapses toward zero while a real supply holds up.

These readouts are worked arithmetic, not measurements. Assume 300 pF of coupling on a 120 V, 60 Hz circuit: that capacitance has a reactance of about 8.8 MΩ, so a 5 MΩ input sees about 59 V, while a 3 kΩ input sees about 0.04 V. Real coupling varies with cable length and spacing. On a 115 you can still unmask a phantom by adding a load, as our guide to measuring voltage on a floating circuit and spotting phantom voltage explains, but the 117 does it at the turn of the dial.

How VoltAlert spots a live conductor

An energized AC conductor is surrounded by an alternating electric field even through its insulation. The 117's VoltAlert sensor sits in the top of the meter; hold that edge near a cord, outlet or wire and it lights a red LED and beeps when it senses AC voltage. Fluke gives two sensitivity settings: Lo for flush wall sockets, power strips and cords, and Hi for recessed sockets, where it works on bare wire down to 24 V. The 115 has no sensor, so you'd carry a separate non-contact pen tester instead.

How AutoVolt decides AC or DC

On the 115 you turn the dial to AC volts or DC volts. The 117 adds a third volts position that, per Fluke's manual, selects AC or DC from whatever is applied across the leads, and sets the input to about 3 kΩ at the same time. That makes it the quick position for a mixed day of receptacles, control transformers and DC supplies.

1. 01

   Set AutoVolt

   One dial position, no AC/DC choice

   →

2. 02

   Probe the circuit

   Input drops to about 3 kΩ (LoZ)

   →

3. 03

   Meter senses AC or DC

   From the signal across the leads

   →

4. 04

   Reads volts

   600.0 V range, ±(2.0% + 3)

The trade-off: a 3 kΩ input draws current from the circuit. On mains wiring that is the point. On a sensor output or a logic rail it can pull the voltage down, so use the normal high-impedance V positions there, which the 117 also has.

Where the 114 and 116 fit

The 115 and 117 belong to a family of four that share the same case, display, CAT III 600V rating and battery. People comparing the 115 and 117 often land on the other two, so here is how Fluke divides the line-up.

The 116 is the one to look at for furnace work: its 600.0 µA range at 0.1 µA resolution covers flame-sensor checks, and it reads a K-type thermocouple from -40 °C to 400 °C. It gives up the A input to do it. Our best multimeter for HVAC technicians guide compares it with HVAC clamp meters.

Fluke 115 vs Fluke 117 for electricians

On a panel or a branch circuit, the two meters carry the same protection. Both are rated CAT III 600V, which covers distribution panels, feeders, fixed wiring and receptacle circuits, and neither carries a CAT IV rating, so neither belongs on the line side of the meter base or the service drop. What changes on an electrician's day is how fast each meter gets you to a trustworthy answer.

Three jobs show the gap. First, finding which cord, receptacle or fixture whip is still energized: the 117 answers from its top edge with VoltAlert before the leads come out of the pouch, while the 115 owner probes each point or carries a separate pen. Second, a reading on a conductor that should be dead, such as a switch leg or an abandoned run pulled through a pipe with live circuits: on the 117, AutoVolt's roughly 3 kΩ input tells a coupled phantom from a real backfeed; on the 115 you have to add a load across the leads to find out. Third, a control cabinet that mixes 24 V AC transformer secondaries with DC sensor supplies: the 117's AutoVolt position reads either without a dial change, while the 115 needs V AC or V DC chosen for each point.

Two rows are identical, and they matter as much as the four that differ. Neither meter's extras replace the live-dead-live test with the leads, and both measure current only in series through the A jack, on a top range of 10.00 A with 20 A allowed for 30 seconds. On feeders and larger motor circuits that means a clamp meter does the amps job; see our electrician's multimeter guide for pairings. For a journeyman or apprentice doing branch-circuit and panel work most days, the 117 is the better match. The 115 holds up for an electrician who already wears a pen tester and knows to load-test any surprise reading.

True RMS differences explained

Both meters are True RMS: our Pick data lists "True RMS" for the Fluke 115 and the Fluke 117, and Fluke's datasheet applies it to AC volts and AC amps on both. True RMS means the meter computes the heating-equivalent value of whatever waveform is on the leads. An average-responding meter instead assumes a clean sine and scales the average, so it drifts when the waveform isn't one.

That matters on the loads electricians now meet daily. A variable-frequency drive chops its output into pulses. LED drivers and switch-mode supplies draw current in short, tall peaks near the top of each cycle rather than a smooth sine. On those circuits, the AC volts and especially the AC amps readings from either Fluke stay trustworthy within spec. The difference between the two meters is not True RMS; it is which dial position you read from.

Worked from those figures for a 277 V LED lighting circuit on the 600.0 V range, where one count is 0.1 V: the dedicated V AC position on either meter allows 1.0% of 277 (2.77 V) plus 3 counts (0.3 V), so about ±3.1 V. The 117's AutoVolt position allows 2.0% of 277 (5.54 V) plus 0.3 V, so about ±5.8 V. For a go/no-go check AutoVolt is fine. For a voltage-drop calculation or a drive-input reading you'll write down, switch the 117 to V AC, where it matches the 115 exactly.

Two limits apply to both meters equally. The quoted bands start at 45 Hz, so a drive slowed below that runs outside the figures we cite. And neither meter lists a low-pass filter, which keeps a drive's switching edges out of the reading on the motor side; the Fluke 87V has one, which is why it leads our Fluke 117 vs Fluke 87V comparison for drive work. On the supply side of a drive, or on LED and electronic-ballast circuits, either True RMS Fluke is the right tool. Our budget True RMS multimeters guide covers lower-cost alternatives.

Fluke 115 vs 117 for home electrical testing

Most homeowners buy a meter for five jobs: checking that a receptacle has power, confirming a breaker really killed a circuit, testing appliance parts such as heating elements and fuses, checking batteries, and chasing a nuisance trip. Both meters do the measuring part of every one of those identically. The difference shows up in the two moments where home wiring most often fools people.

The first is "is it off?". After flipping a breaker, the 117 lets you sweep the receptacle or switch box with VoltAlert to confirm the circuit you killed is the one you're about to touch, then prove it with the leads. The second is the half-dead outlet that reads 30 or 40 volts: on house wiring that is often coupling from a neighboring cable, and the 117's LoZ position shows whether it is real. On a 115 you can still get there, but you need a separate non-contact tester and a load-test habit.

The last row is worth the arithmetic. A 1,500 W space heater on 120 V draws 1,500 ÷ 120 = 12.5 A, which is above both meters' 10.00 A range; Fluke allows 20 A for only 30 seconds. Measuring it means breaking the circuit and routing the full load through the meter, so a homeowner is better served by a clamp meter for appliance current. For tripping breakers, start with our guide to why a circuit breaker keeps tripping.

Which is enough? If you will open receptacle and switch boxes yourself, the 117 is the one we recommend, because its two extras target exactly the checks that keep you safe. If your work stops at unplugged appliances, cords, batteries and reading outlets with the leads, and you already own a pen tester, the 115 is plenty, and it usually costs less. Both are more meter than many homes need; our best multimeter for home use guide covers simpler options, and anything at the panel itself is a job for a licensed electrician.

Fluke 115 vs 117: which should you buy?

For a wider shortlist by trade, see our best multimeter for electricians guide or the full best multimeters roundup.

What neither meter does

• No temperature. In this family only the Fluke 116 reads a thermocouple. The Fluke 179 also measures temperature with its supplied probe.
• No mA or µA ranges. The lowest current range is 6.000 A with 1 mA resolution, too coarse for standby current or flame sensors. See our guides to measuring microamps and the best meters for microamps.
• No logging or app. Min/Max/Avg captures extremes on the display, but neither meter stores readings or connects to a phone.
• No CAT IV rating. Both stop at CAT III 600V. For service entrances and outdoor feeds, the Fluke 87V and Fluke 179 are rated CAT IV 600V / CAT III 1000V; compare them in Fluke 117 vs Fluke 87V and Fluke 87V vs Fluke 179.

Frequently asked questions