Surge Protector Ratings
On a listed surge protector, you should find a couple of ratings. Look for:
- Clamping voltage: This tells you what voltage will cause the MOVs to conduct electricity to the ground line. A lower clamping voltage indicates better protection. There are three levels of protection in the UL rating — 330 V, 400 V and 500 V. Generally, a clamping voltage more than 400 V is too high.
- Energy absorption/dissipation: This rating, given in joules, tells you how much energy the surge protector can absorb before it fails. A higher number indicates greater protection. Look for a protector that is at least rated at 200 to 400 joules. For better protection, look for a rating of 600 joules or more.
- Response time: Surge protectors don't kick in immediately; there is a very slight delay as they respond to the power surge. A longer response means your equipment will be exposed to the surge for a greater amount of time. Look for a surge protector that responds in less than one nanosecond.
Better surge protectors may come with some sort of guarantee of their performance. If you're shopping for more expensive units, look for a protector that comes with a guarantee on your equipment. If the unit fails to protect your equipment from a power surge, the company will replace it.
Surge Protector FAQ
What does a surge protector do?
Are all power strips surge protectors?
Is a whole-house surge protector worth the money?
What are the types of surge protectors?
Do wall outlets have surge protection?
Originally Published: Jan 5, 2001