Fluke Multimeter FAQ: 117 vs 87V MAX, STIHL MS 170 Spark Plug, and Generator Noise

I'm the person who keeps our shop's checklist. I've been a maintenance tech for over seven years, and I've personally made and documented 14 significant mistakes that added up to roughly $8,000 in wasted budget. So before you buy another tool or pull another panel cover, here are the questions I wish someone had walked me through.

Use this however you want. Jump to the question you care about:

1. What actually makes a Fluke multimeter worth it?
2. Fluke 117 vs. 87V MAX: which one should I buy first?
3. Where can I find the Fluke 87V MAX multimeter manual?
4. What is the correct STIHL MS 170 spark plug gap?
5. What should I know before updating an electrical panel?
6. What is the most quiet generator?
7. Do small shops really need calibration certificates?

What actually makes a Fluke multimeter worth it?

Fluke multimeters are not magic. They're predictable. In my first year, I thought I was paying for the brand. Then I compared a 15-year-old Fluke 87 with a different meter on the same VFD circuit. The Fluke stayed steady on the True RMS reading; the other one jumped around. That was the moment I understood why specs show up on the invoice.

At least, that's been my experience in industrial maintenance and small side work. You don't need a Fluke for every single measurement, but if you work around motors, drives, or panelboards, True RMS is not an optional add-on. It's basically the difference between guessing and knowing.

Fluke 117 vs. 87V MAX: which one should I buy first?

Start with the Fluke 117 unless you live inside control panels. The 117 is the everyday electrician's meter: it's lighter, it has non-contact voltage detection, and it still gives you True RMS readings. If you search for a Fluke 117 multimeter image, you'll see the yellow body and the rounded top where the VoltAlert sensor sits. I've bought two of them because the first one grew legs at a job site, which says something.

The Fluke 87V MAX is the meter I reach for when I need more accuracy or when I'm working on variable frequency drives. Fluke lists the 87V MAX DC voltage accuracy at around ±0.05% + 1 count, while the 117 is around ±0.5% + 2 counts. Let me rephrase that: the 87V is not a daily carry for checking outlet voltage. It's a specialist. When I compared the 117 and the 87V MAX side by side on the same failing motor circuit, I finally understood where the extra money goes. It goes into the fine print, not the color of the case.

Where can I find the Fluke 87V MAX multimeter manual?

Right now. Stop using a third-party PDF. The full Fluke 87V MAX multimeter manual is a free PDF on Fluke's official website. I keep a copy in my phone and an abbreviated card in my tool bag. The manual matters because it lists the input ratings, the safety category ratings, and the accuracy specs that you won't remember two months from now.

In 2022, I wasted half a day chasing a ghost voltage on a lighting panel. The fix was embarrassingly simple: I needed the low-impedance mode on my 117 to drop the ghost voltage and give a useful reading. The manual had explained that mode, but I had skipped that page. (Should mention: it was in the 117 manual, not the 87V MAX, but the habit is the same.) Oh, and the safety ratings in the manual are not a suggestion.

What is the correct STIHL MS 170 spark plug gap?

The STIHL MS 170 spark plug is usually an NGK BPMR7A or the Bosch equivalent. I use the NGK and set the gap to 0.5 mm, which is about 0.020 inch. Your current production year might list a different number, so check the saw's manual or the emissions sticker. The 0.5 mm spec is the one I've seen in STIHL documentation, but I still check the saw itself.

In my first year, I made the classic beginner mistake: I installed the right spark plug number without checking the gap. It looked correct, it ran, but it ran rough under load. The customer called me back. That mistake cost me a free service visit and an education in the difference between same part number and ready to install. I should add that this is a small repair, but I treat it like a real job because the customer who calls about a chainsaw spark plug is the same person who later calls about a panel change.

What should I know before updating an electrical panel?

Updating electrical panel code requirements vary by area, but the planning process is the same at every job size. The thing people skip is the workspace. NEC 110.26 generally requires 30 inches of clearance in front of electrical equipment and 36 inches of depth. Verify the current code with your local inspector, but don't design a panel that can't be worked on safely.

I once treated a small 100-amp panel change for a retired couple as the quick job on my list. It wasn't. The couple's utility room had no working space at all, and I had to move the whole panel. The lesson was not about torque specs; it was about attitude. I created a formal sign-off sheet after that. We didn't have a formal panel-change checklist before then, and it showed. If you're updating an electrical panel, put your budget into the load calculation, the correct breakers, and the permit—not just the shiny main breaker.

I have a sticky note by my phone that says: Small doesn't mean unimportant. It means potential.

What is the most quiet generator?

There is no single most quiet generator because sound depends on load, distance, and the surface it sits on. Most manufacturers quote sound at 23 ft (7 m) under reduced load. At full load, the number is louder. What I mean is: a 2,000W inverter generator rated at 52 dBA can sound like a different machine when you plug a heater into it.

For most people, the quietest useful generator is an inverter type, not an open-frame construction generator. In 2024, I measured a customer's 2,000W inverter unit at roughly 58 dBA at 7 meters with a phone app. That's not calibrated test equipment—I should add that before I get accused of quoting fake data—but it was directionally useful. The bottom line is, if your goal is the quiet generator, compare inverter models at the same load level and ask for the measurement distance.

Do small shops really need calibration certificates?

Yes, if you are being paid to prove something. I used to skip calibration documentation because I thought it was only for big companies. Then in 2019, I had to defend a measurement on a third-party job without paperwork. The meter was fine. My process wasn't. The re-test and documentation cost me about $1,100 and a week of scheduling headaches.

Now I order calibration with the meter when it makes sense, and I keep the certificate file for every test instrument. It's not a corporate luxury. It's the tool that makes your measurement worth anything. This is one of those process gaps that stays invisible until a client asks for proof.

And that's the list. If you read any of this from a search result, start with the smallest correction first. The spark plug gap takes five minutes. The panel checklist takes an afternoon. The meter decision is the one that affects the rest.