MOV for 120VAC Appliance Surge Protection

Question

Problem: MOV for 120VAC Appliance Surge Protection. Solve this hands-on electronics task on EWskills.

Accepted Answer

1. Component Purpose

This is the same concept as the 230VAC MOV, but sized for the US 120VAC market. The MOV sits across the AC input after the fuse and clamps voltage surges to protect the appliance’s power supply and electronics.

For 120VAC mains, the standard MOV rating is 150VAC maximum continuous. This provides headroom above 120V nominal (which peaks at ~170V) while still giving effective clamping.

Required: 150VAC · ≥4.5kA surge · ≥50J · 1-Circuit · Disc · Through Hole · Littelfuse · RoHS

2. How to Find It on DigiKey

Go to DigiKey.com → Circuit Protection → Varistors, MOVs

Apply these filters:

Maximum AC Volts → 150V
Current - Surge → 4.5kA or higher
Energy → 50J or higher
Number of Circuits → 1
Mounting Type → Through Hole
Package / Case → Disc
Manufacturer → Littelfuse Inc.
Part Status → Active

Tip: For consumer appliances, UL/CSA safety certification often requires the MOV to be in series with a fuse. The fuse disconnects the degraded MOV before it reaches thermal runaway.

3. Key Specifications & What They Mean

Specification	Required	Why
Max AC Volts	150V	Standard for 120VAC US mains.
Surge Current	≥4.5kA	Adequate for consumer/appliance use.
Energy	≥50J	Handles repeated consumer mains surges.
Circuits	1	Single line-to-neutral protection.
Package	Disc, Through Hole	Standard MOV form.
Manufacturer	Littelfuse	Company AVL requirement.
Temp Range	−40°C to +85°C	Standard operating range.
RoHS	Yes	Compliance required.

4. Selecting a Safe, Production-Ready Part

The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?

Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide

5. Filtered DigiKey Link

➡ View Matching Parts — Littelfuse, MOV, 150VAC, ≥4.5kA, ≥50J, Disc

21. MOV for 120VAC Appliance Surge Protection