Leviton Switch Installation, High Voltage Relays, and a Black Air Filter: A Quality Inspector's Straight Answers

I'm a quality compliance manager for an electrical equipment company, and I review roughly 400 unique SKUs a year. In 2025, I've already rejected 8% of first deliveries because of spec mismatches. This article is a round-up of the questions I keep answering—about Leviton switch installation, Leviton push button switches, high voltage relays, that odd R44TS spark plug request, and the mystery of why an air filter turns black. Each answer stands alone, so skip around if you want.

• What are the most common Leviton switch installation mistakes?
• Is the Leviton push button switch worth it for commercial spaces?
• How do I pick a high voltage relay that survives continuous duty?
• What should I know about R44TS spark plugs in a generator maintenance list?
• Why is my air filter black after a few weeks?
• Is the Leviton switch premium worth paying when you're on a deadline?

What are the most common Leviton switch installation mistakes?

The big one is assuming a smart switch needs a neutral wire. Older buildings especially can have just two wires in the box. Leviton's smart switches include no-neutral models for exactly that situation, but you have to order the right variant. I once had a contractor order 400 standard smart switches for a retrofit where the boxes had no neutral. We didn't verify ahead of time. The whole job stalled for a week. That was one of those "it'll be fine" assumptions that cost everyone time.

Another mistake: overtightening the terminal screws. We saw stripped terminals on a set of returned switches, and most were torqued way past spec. The screw should seat snug, but not to the point of deformation. I've had good luck using a torque screwdriver set to the manufacturer's recommendation. There's something satisfying about hearing that click and knowing it's right.

Also, don't assume the same Leviton switch works in a 3-way setup without checking the package insert. One model is not always interchangeable. The package will say "suitable for 3-way installations." If it doesn't, you're going to spend an evening chasing wires.

Is the Leviton push button switch worth it for commercial spaces?

If you've ever put your hand on a cheap push button that catches or feels mushy, you know why this question comes up. The Leviton push button switch has a clean, positive actuation. In a conference room or a retail storefront, that tactile feel reads as higher quality to visitors.

But it's a trade-off. A standard toggle will take more repetitive abuse in a corridor. I went back and forth with a facilities manager for two weeks: push button looked great in the lobby, toggles were simpler for the back hallways. We ended up with push buttons in the lobby and toggles everywhere else. On a 2,000-unit order, the cost difference was about $0.80 per device—$1,600 to get the entrance feeling right. That was worth it.

How do I pick a high voltage relay that survives continuous duty?

Start with the coil voltage. That's the voltage that energizes the relay, not the contacts. We had a batch of "250VAC 30A" relays where someone interpreted "30A" as everything. The coil was 24VDC, but it was wired to 120VAC. That was a $4,000 mistake and a delayed panel shipment. Now every contract includes a coil voltage verification step.

Then pay attention to the type of load. A relay rated for 30A resistive can handle a lot less when you're switching inductive loads—motors, contactors, solenoids. The inrush current is much higher. I've linked the spec sheet to the order every time a high voltage relay goes into a motor control panel. And derate: if your load is 25A continuous, don't use a 30A relay. I use 80% of the contact rating as the practical maximum.

Also look for UL 508 listing—it means the relay has been tested for industrial control cycles. A relay that looks identical but lacks that listing has probably not been tested the same way. The cheap one might work for a while, but "a while" is not a schedule.

What should I know about R44TS spark plugs in a generator maintenance list?

R44TS spark plugs keep showing up in maintenance lists, and I'll be honest: I'm not an engine specialist. But quality principles apply to spark plugs like the R44TS. Check the gap with a feeler gauge, make sure the heat range matches your application, and buy from a real distributor. Counterfeit plugs are a thing. A plug that's gapped wrong can cause a misfire, which is exactly the kind of failure that hurts productivity.

The "R" in R44TS means it's a resistor spark plug, which reduces electromagnetic interference. If you're working around sensitive control electronics—and a high voltage relay cabinet counts—that matters. Don't swap in a non-resistor plug because it "looks like the same thing." You'll get noise that can make relays chatter, and that will drive you insane.

If a generator set uses R44TS and it fails after 500 hours, look at the electrode color. If it's black and sooty, it's running rich—or your air filter is doing a bad job. Which brings me to the next question.

Why is my air filter black after a few weeks?

An air filter that's black in a short time is catching soot or carbon dust. In an electrical enclosure, that's a warning sign. I found a cabinet where the return air filter had turned black because a high voltage relay was arcing internally. The arc had pitted the contacts, and carbon particulate got pulled into the enclosure fan.

Black is not normal dust. Dust is gray or brown. Black means something is burning—or at least arcing. If it's an HVAC filter, the culprit might be a nearby diesel exhaust, a burner that's running rich, or a chimney leak. Don't just swap the filter and move on. Check for visible arcing on contactors, unusual ozone smell, and any carbon tracking on the enclosure walls. One facility ignored a black filter for three months and ended up with a relay failure that cost $2,300 in after-hours labor.

Actually, a black filter can also be caused by a failed motor brush in a packaged unit. So the first step is always: isolate the source before replacing anything.

Is the Leviton switch premium worth paying when you're on a deadline?

In March 2024, we paid an extra $400 for rush delivery of specific Leviton switches. The alternative was missing a $15,000 installation event. That's the easiest decision I've ever made. Rush delivery is not just about speed—it's about certainty. When the deadline is hard, you're not buying speed; you're buying the guarantee that the switch will be there and will work when it arrives.

I get why people go with the budget option. Budgets are real. But in a time-pressured project, a generic switch with a slightly off spec can turn into a troubleshooting session at the worst possible moment. In my own experience, a cheap switch can save 12% upfront, then cost 30% in rework and delays. If the project keeps you up at night, pay the premium and get some sleep. There's something satisfying about a rush order that arrives on time and works exactly as specified.