21. MOV for 120VAC Appliance Surge Protection
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