Rey

Hi folks,

This is my first post and most definitely will not be my last. I have tried looking for more information in here and come up short. It is a two part question:

1) Since surge protectors work by dumping excessive voltages to the grounding wire, an attempt to plug any sensitive equipment into a surge protector when a residence only has a two prong system (ungrounded) would only mean you are just using an expensive power strip correct?

2) What about plugging in a surge protector into a GFCI plug that has replaced a two prong plug (still ungrounded) but GFCI protected? What does this achieve? Same as above?

Thanks in advance

Dennis Alwon

If really don't know much about this but it will definitely work if installed at the panel. I have used the surge suppressors that you install in a panel on the buss bar. It looks like a breaker but isn't.

They have some that will replace a dp 20 amp circuit so that the breaker itself is a surge suppressor

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Rey

@Dennis Alwon, thanks for the reply. That is interesting...I'm more specifically referring to the power strip type.

splatz

You are correct, most surge strips rely on the ground for protection, they use MOVs to shunt the surge current. However you can find surge protection devices that use other ways, some use silicone avalanche diodes or big chokes / inductors for series mode protection. You also may be able to use an isolation transformer.

As Dennis pointed out even if the circuits are two wire you can install protection at the panel, that type of protection is supposedly not quite as good for sensitive electronics as a quality surge strip, but I think it's still pretty good protection.

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drsparky

We use MOVs and SASD such as a Transtector APEX IV and a lot of their other products.
Here is a link to transtector, lots of good information.
https://www.transtector.com/

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Rey

Thanks @drsparky, I will check it out.

active1

Another new member

Mike_kilroy

1) still big help! Take one apart sometime and see. Good one has 3 MOVs. Each line to ground AND ONE ACROSS THE LINE. So u still get protection.

2) still helps! It can still open the circuit on lightening strikes. Mine do all the time and remember the ground does nothing on a gfci (for detecting anything)

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Rey

@Mike_kilroy could you please clarify your response to both parts of my question. Not many lightning strikes in my neck of the woods. Before your response, I was under the impression from the other responses that the surge protector strips were of no use without a grounding wire or with a gfci receptacle (I do realize that a gfci receptacle has no ground). Thanks in advance.

brian john

A good quality plug strip SPD (Surge Protection Device) has 3 MOV's Line to neutral, neutral to ground, and line to ground.

The best protection is with multi level SPD one at the panel and one at point of use.

A properly installed SPD at the panel will have leads as short as possible, as straight as possible no sharp bends and the conductors tightly ty-wrapped together.

A GEC should also avoid sharp bends but no one does, inspectors sweat over two ground rods then the GEC to the rods has nice neat sharp bends,

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Mike_kilroy

Not sure what kind of clarification you want... Brian repeated my first point, that there are 3 MOVs in the surge protector... Perhaps you want to google "what is an electrical surge?"

Lightening was just a good example of a surge. If I ventured a guess, it causes 80% of all surges. Glad to hear you live where there is not lightening!

So what clarification can I add to point 1? Hmmm... how about info on the MOVs used... 120Vac rms line has 160Vpeaks... So 180-200V MOVs typically are used. When the line voltage goes above their rated voltage, they CLAMP: means they short both their leads together. So the one across the line in the surge protector SHORTs out the surge, preventing it from remaining, thus protecting the equipment plugged into it. Just because there are not 2 more to ground does not mean the one will not work.

For clarification on your point 2, perhaps google "how does a GFCI work." The ground has nothing to do with its operation. When it sees current not equal in both legs of the line, it opens the circuit to the load. Ground not involved at all. So if a surge makes huge current, it is likely to not be equal down to a few ma, thus it opens. So not having a ground attached makes zero difference in the case of the surge.

Hope this helps?

Rey

So @Mike_kilroy, for these homes with un-grounded two-prong wiring, if the home owner decides to pass on running a new 14-2 or 12-2 with ground to provide a properly grounded circuit, installing a GFCI plug and plugging in a surge protected strip into the outlet to plug their laptop or other sensitive electronics would offer two level protection from both the GFCI and the L-N MOV? The GFCI is almost needed too because all of the surge strips have 3 prong plugs. Thanks in advance for getting back to me.

Mike_kilroy

IN MY OPINION, sorta yes, BUT I would not "recommend" that in lieu of a correct upgrade. Now, if it were a 84 year old gramma on SS who absolutely could not afford ugrading properly, then I would do both things you mention for her.

I am not sure how you relate the fact that power strip has 3 prong plug to requiring a GFCI... hmmm... well maybe I see where you are headed... If the gnd prong was real, and a 3 prong device is plugged in, there is a good chance the case of the thing plugged in will be grounded... so without that, adding a GFCI will offer a level of protection against current going somewhere other than between the hot and neutral... OK, I agree - good thinkin'

Rey

All I meant was that all of the surge protector strips have grounded plugs on them so there is no way of plugging them into a two prong outlet so replacing with a GFCI outlet makes more sense both offering protection by sensing a differential in L-N and then adding convenience of a 3 prong plug. And then the other level of protection just comes from simply having the L-N MOV. As you said in your initial post...better than nothing.

scotch

Maybe just instal a "whole House " surge suppressor at the panel ...it has much bigger MOVs and can probably survive surges a lot longer....it also has indication of failure of the MOVs.