Mean Well LRS-150-48

Mean Well LRS-150-48 — 150W 48V 3.3A enclosed switching PSU

A fanless, low-profile (1U / 30mm) enclosed switching supply from Mean Well's LRS line. 48V DC out, 3.3A, 158.4W maximum. This is the silent, compact brick you bolt into a printer base or control cabinet and forget about.

Read this first: the 48V variant is not the standard printer part

Most 3D printers — Voron, RatRig, the common Klipper/Ender builds — run their bed heater, mainboard, and electronics on 24V. That is the Voron standard. This is the 48V unit, which is a different animal:

• It is for high-voltage stepper drivers and industrial loads, not a 24V bed heater. Some builders run steppers at 48V for higher top speed and acceleration headroom (driver permitting — check your driver's max input, e.g. TMC5160-class), and 48V is common in CNC and industrial gear.
• Do not wire a 24V bed heater, 24V hotend, 24V fans, or a 24V mainboard to this. Feeding 48V into 24V-rated hardware will destroy it. If you came here for a standard Voron/Klipper bed + electronics supply, you want the LRS-150-24 (or a larger 24V unit sized to your bed), not this part.
• For powering a Raspberry Pi / SBC / MCU, you want a 5V supply (or a buck converter), not this.

Bought with eyes open, the LRS-150-48 is a clean, proven 48V rail. Bought by mistake, it's a fast way to let the magic smoke out of your electronics. We'd rather you know.

The wiring and safety reality (bare mains terminals)

This is an open-frame-style enclosed supply with a screw-terminal block, not a sealed wall-wart. Live AC mains lands on exposed screw terminals (Line / Neutral / Earth) right next to the DC output terminals (+V / -V). That means:

• You are responsible for the mains side. You provide the AC cabling, strain relief, an inline fuse on the Line conductor, and a proper earth (ground) connection to the chassis. None of that is included.
• The terminals are touch-live when powered. Mount it inside an enclosure or behind a guard so nobody can contact the AC terminals. Set the 115/230V input switch correctly for your mains before first power-on — wrong position on 230V mains can damage the unit.
• If you're not comfortable terminating mains AC, fusing it, and earthing the chassis, this is not the right product for you — buy a sealed external brick instead. There's no shame in it.

Why this form factor

The LRS series is the go-to for printer and cabinet builds because it's fanless (convection cooled — no fan to fail, no fan noise) and thin (30mm tall), so it tucks into a printer base or DIN-adjacent control area without a tower-sized footprint. ~90% efficient, wide 85-264VAC input, and the usual Mean Well protection set: over-voltage, overload, over-temperature, and short-circuit. UL/TUV/CB/CE listed, 3-year warranty from Mean Well.

Honest spec notes

• Full output across the input range: the full 3.3A / 158.4W is available over the entire 85-264VAC input, on both the 115V and 230V switch settings. (On 115V mains the AC input current is roughly double that on 230V — normal P=VI behavior — but the DC output is not derated.)
• Thermal derating: rated to +70C ambient, but you lose available current above roughly +50C. Convection cooling means airflow and orientation matter inside a hot enclosure.
• Single output: one 48V rail, adjustable a few percent (43.2-52.8V) via the onboard trim pot.

On clearance — solid Mean Well silicon at a clearance price. Just make sure 48V is actually the rail your build needs before you buy.