Garage Door Surge Protection

Sure, if you want cheap/wimpy, you can just use a 1-socket type, that hangs on the receptacle. Just replace it every year or two.

But if it were me, I'd be super sick of replacing garage door openers. I'd go industrial grade, a "whole house" unit like this, wired to protect 120V. Mount it by removing the garage door recep, adding a steel box extension to the junction box, giving you a bunch of side knockouts. Mount this critter in a knockout, and then put the outlet back (on the extension).

Long cable runs have a damping effect on surges. So by putting this "whole house suppressor" here, you amplify its power... it's not being used up trying to damp surges in your whole neigborhood, and just focuses on doing a great job protecting your opener.

This thing is a beast, and it's dedicated to protecting your opener. It'll probably outlive both of us lol.

seharper said:

Sure. Install one there also, but protecting the whole house is not my goal today.

You missed my entire point. I'm not trying to protect the entire panel with a unit at the garage door site. I'm only trying to protect the garage door site, with a unit that is overkill.

That long #12 cable is a passive benefit, because it dampens out some spikes all by itself. And those are spikes the surge doesn't have to deal with. Which amplifies the power of an already very powerful surge suppressor.

Click to expand...

No, I didn't miss your point. You don't understand what is required for a surge protection device to be effective. Just because it has heavy duty specs compared to a type 3 SPD will not make it significantly more effective when you place it at the GDO.

Those long wires that you claim will dampen out the spike will in fact reduce its ability to quickly divert the energy of the surge to ground. The fact that there is a ground wire in the junction box isn't what matters. It is the distance the surge has to travel from the SPD back to the panel and earth ground that's important. Keeping it short matters greatly. It needs the lowest possible impedance path to earth ground in order to be effective.

Best practice is to stop the surge from getting past the meter and/or the breaker panel in the first place. That will protect the GDO and everything else.


If you want to place a type 3 SPD at the GDO, sure go ahead. But without a type 1 or type 2 back at the panel, you're fooling yourself that things will be fine. Upgrading it to a type 2 at the GDO won't be much better.

Sometimes it's cheaper to have good low deductible home owners insurance and a good working relationship with your provider agent. Better yet, if you are a blood relative of the agent! lol

But seriously, of you live in an area that has proven by past history to have surge damage often, it's a good idea to try to stop it at the point of connection and with as short of a ground path as possible and a conductor size a couple of sizes larger than you would ordinarily think necessary.

GDO's have fragile components that are always on-line in order to be ready for operation at all hours. They are equally as vulnerable as your computer (perhaps more so) and although less expensive to replace, may be worth the effort to protect them adequately. Mine aren't and I have never had any problems... neither is my computer... likewise no problem other than the modem got fried once but that was replaced on the cable providers' dime. YMMV

RAL238 said:

Those long wires that you claim will dampen out the spike will in fact reduce its ability to quickly divert the energy of the surge to ground. The fact that there is a ground wire in the junction box isn't what matters. It is the distance the surge has to travel from the SPD back to the panel and earth ground that's important.

Click to expand...

Sure, and I hear what you say on that.

However, protecting the garage door opener doesn't require getting to solid ground. All that's required is for the hot, neutral and ground to be kept near 120V relative to each other.

Let's say a 2000V surge rolls down the hot line. The surge protector tries to cancel the 2000V to ground, but as you say, isn't very effective because of the distance. So ground gets pulled up to 1000V, and you say that's bad. I say "But hold on. What's happened with neutral and hot?" Well, neutral has hopped up to 1000V also, and hot is 1120V. The whole kaboodle leapt momentarily, but H-N-G relative to each other are well within limits. The garage door opener sees no surge, and has no idea it was momentarily biased at 1000V. It simply sees the 120V differential voltage it's supposed to.

It's like birds. If a bird flies from the ground to a hot wire, it doesn't care. It simply has a different *bias*.

I think the vulnerability of the GDO to surges is through all the low voltage wiring that is acting like antennas to direct lightning induced surges into the sensitive components of the GDO. Lets face it, if the surges were coming via the line voltage, it's going to hit some other stuff in the house as well.

It may well be one of those situations where it would be better to not have the equipment grounded at all, since that causes more surge current to flow than would occur if it didn't have an encouraging path to ground.

Now before I get flamed let me clarify, I don't suggest disconnecting the EGC, but if I had this problem, I'd take measures to protect the front end of the sensitive circuits and pay less attention to the power source. Surges on those "antennas" are of very high impedance and just about any respectable surge device can handle them without self destructing.