How to Mount a Meanwell LRS-350-24 in an Enclosure: 7 Steps

Office administrator for a 45-person manufacturing company. I manage all the maintenance and electrical component ordering—roughly $80,000 a year across 15 vendors. When I took over purchasing in 2020, I ordered a Meanwell LRS-350-24 for one of our inspection machines. I passed it to our tech and assumed the hard part was done. Three months later, the unit failed.

It wasn't the power supply's fault. It was the enclosure. We'd mounted the LRS-350-24 in a sealed box without enough airflow, and the fan basically cooked itself. That's a $150 mistake, and honestly, it was mine. The tech told me the clearance was tight. I told him it would be fine. It wasn't.

So this is the checklist I've used ever since when we put a Meanwell power supply into an enclosure. If you're holding an LRS-350-24 (or the -12/-48 versions—same case, different spec), this is everything I check. Seven steps, about 45 minutes.

Step 1: Read the nameplate before you do anything

I know this sounds obvious. It's also the step I've messed up. The LRS-350 series includes a few models that all look identical from the outside: the -24 is 24V/14.6A/350W, the -12 is 12V/29A, and the -48 is 48V/7.3A. Same physical dimensions, similar label layout.

Check the model number, the output rating, and the date code when the unit arrives. Confirm the input range too—the exact spec is printed on the label, and it's not worth assuming. In 2022, I ordered six units and two turned out to be the 48V version because I copied the wrong SKU from my own spreadsheet. We caught it during receiving only because label checks are part of the routine. Thirty seconds of checking is way cheaper than the alternative.

Step 2: Measure the case and plan the airflow, not just the footprint

The LRS-350-24 is 215 x 115 x 50 mm and has a built-in fan. On paper, it fits in a small enclosure. But “fits” and “works” are different things once you add wire bends and airflow.

Check Mean Well's official datasheet for the current clearance figures before you order an enclosure. My working rule is at least 30 mm above and below, and about 25 mm on the airflow sides. If your enclosure is sealed and can't move air, you're basically running a 350 W supply inside a thermos. It'll work for a while. It won't work for long.

That was exactly my 2020 mistake. The replacement went into a ventilated enclosure and has been running for two years without a problem. Same model, different box, different result.

Step 3: Pick an enclosure that helps, not one that just holds

For the LRS-350 series, I prefer a ventilated steel enclosure. Why:

• Steel is straightforward to bond to a proper ground (more on this in Step 6).
• Ventilation slots let the fan actually move air.
• Steel is easy to modify if you need cable glands or a panel-mount connector.

A suitable enclosure around 250 x 160 x 80 mm runs about $25–45 depending on the supplier—but prices change, so verify current quotes. Aluminum dissipates heat well and weighs less, but you'll pay more. ABS plastic is acceptable for light bench duty, but I wouldn't put a 350 W continuous load inside a sealed plastic box.

And if you were hoping to DIN-rail mount this model: the LRS series is chassis-mount. You'd need an adapter plate or a different Mean Well model designed for DIN rail (like the NDR or EDR series). Don't hang 350 W off a plastic DIN clip that isn't rated for it.

Step 4: Mount it so the fan can actually breathe

Check where the fan is on the specific unit before mounting. (Different Meanwells have different layouts, even within the same series.) Orient the PSU so the fan isn't buried against a solid surface. Use M4 screws in the designated mounting holes. Don't overtighten—the aluminum case strips if you treat it like a steel frame. Hand-tightening with a screwdriver is enough.

Also leave room for the wire bends at the terminal blocks. This gets overlooked all the time. The enclosure looks plenty roomy on paper, then you add the 14 AWG wire and suddenly the lid doesn't sit flush. Plan the bend radius, not just the rectangle of the PSU.

Step 5: Wire with the right gauge and strain relief

For the 24V output at 14.6A, use 14 AWG as a minimum for short runs. If the load is more than about a meter from the PSU, step up to 12 AWG to keep voltage drop under control. For the AC input side, 16 or 18 AWG is usually enough at this wattage, but check your local code.

Use a proper IEC inlet (like a C14 connector) for AC input. Install strain relief bushings on any wire that exits the enclosure. I learned this one the hard way: a maintenance guy snagged a cord and pulled a terminal block clean off the board. That turned a $150 power supply into a $150 repair, plus half a day of downtime.

Step 6: Ground it properly

The LRS-350-24 has a ground terminal between the AC and DC connections, plus a grounding screw on the case. Use both.

In a metal enclosure, run a dedicated ground wire from the PSU's ground point to the enclosure's grounding stud. If the enclosure is painted, use a star washer so the connection bites through the paint. This won't show up as a problem during a bench test, but it matters a lot in a fault condition.

I also add an external fuse or breaker on the AC line. The Meanwell's internal protections (short circuit, overload, overvoltage, over-temperature) are good features, but they're last-resort features. Your first line of defense should be a properly sized external overcurrent device.

Step 7: Test, verify, then close the box

Don't bolt the lid on and hope. Bench test first:

• Output voltage reads 24V ±1%, roughly 23.8 to 24.2V. Outside that range, look at the wiring and the load.
• The fan is moving air through the enclosure vents—not just spinning, actually moving air.
• Case temperature after 20–30 minutes under a realistic load. Use an IR thermometer. If you can't keep your hand on the surface, your airflow plan is wrong.

And understand the indicator LED and the printed symbols on the label before you rely on them. That's kind of like checking the symbols on a blood pressure monitor: you read them when you first get the device, not when something goes wrong mid-use.

Common mistakes I've seen (and made)

• Choosing a bigger sealed box instead of a ventilated one. A larger sealed box just delays the same thermal failure.
• Screws that are too long poking into the internal board from the underside of the case. Keep them short; a couple of millimeters of bite is plenty.
• Swapping AC and DC terminals under time pressure. The labels are clear, so read them twice.
• Leaving out strain relief because the cable “fits snug.” Until it doesn't.
• Not labeling the outside of the enclosure with the output voltage and model. If you have more than one Meanwell in your building, a permanent marker takes ten seconds and prevents a wrong connection next year.

Final thought

This checklist is really about doing the check now so you don't pay for it later. My 2020 failure cost us a week of production time and taught me that most power supply problems are installation problems, not product problems.

I can only speak to our experience—a small manufacturing facility with typical control-panel loads. If you're building outdoor or high-humidity installations, you'll need to go beyond this: IP-rated enclosures, conformal coating, maybe some thermal modeling. This list is the baseline for a routine shop-floor install.

Since 2020, every Meanwell I installed while following this checklist is still running. The ones that failed failed right after I got lazy. That's not a product-shaming statement—it's just airflow, wiring, and a little bit of patience in the right order.

Five minutes of verification beats five days of correction.