GFCI vs Surge protector

I was going to look into this on my own and not here but thought why not ask the pro’s so others could learn also if needed.
What is the difference between a GFCI and a surge protector?
I had a Elec friend tell me that a GFCI is not the same as a surge protector and i agree but do they do the same thing?
Paul, i expect you to give me a GREAT answer!
Thanks a lot!
Andy B

I’ll try. A GFCI protects from ground faults (such as an electrical short), whereas a surge protector protects against surges (such as a lightning strike or a power outage). You can buy a surge protector with built-in GFCI protection. In fact, all of my surge protectors have built-in GFCI and a test and reset button.

A GFCI looks for a current imbalance in the hot and neutral wires. The assumption is that any current supplied by the hot wire that does not return through the neutral wire is finding its way to ground via your body. I don’t know exactly what the current trip threshold is, but it is in the neighborhood of 15-30 milliamps. And it trips very quickly.

A surge protector protects against excessive voltage resulting from a lightning strike or similar event. I am less familiar with them, so I will let someone else chim in here.

As has been mentioned, GFCI protection is for personnel protection. The devices are set to open at between 4 and 6 miliamps. That would be considered an “A” type of device. There are also “B” type devices that are set to open between 20 and 40 miliamps. The “B” types have a larger range as the manufacturer will have different settings based on the type of usage. The “B” type is more for Equipment protection, not personnel protection, such as Snow melting and Deicing type equipment.

Surge protective devices, and TVSS (transient voltage surge suppression) are much different than GFCI protection. This has become a very complex part of the industry and more information can be found by Googling the topic.
There are two different Articles in the NEC for the two different types of protection (1.Surge protection, 2. TVSS protection). Art 280 Surge Arresters, and Art 285 TVSS.

Generally speaking, there are 2 main differences between Surge Arresters and TVSS.

  1. Location of installation of the two.(**Surge Arresters-**Line side of service disconnecting means, TVSS-load side of service disconnecting means)
  2. Type of protection they offer,. Each offers different types of protection (Generally: Surge Arresters-Lightning, high voltage, TVSS-transients).

Useful post, Pierre. Thanks.
I hope you join NACHI before you get to 100 posts.

Thanks Russel.
I do not think I can join NACHI. I am an electrical inspector and Instructor.

I do think that this organization is trying to improve the HI industry, that is why I post here. It also helps me keep aware of how your industry interacts with the electrical industry in general.

Thanks Pierre for comming by and please keep doing and adding where you can much appreciated by all.

Roy Cooke

Anyone can join NACHI providing that they pass the appropriate tests, have the appropriate nowledge, etc. We have a couple of Realtors who are members here, and we probably have some electricians and others. That notwithstanding, I do hope you’ll continue posting here. We appreciate your efforts to help our members and industry. Thanks.

Ahh…hello…I am an Electrical Inspector, Master Electrician and Instructor…sure you can JOIN !

And I see this topic is already covered so I will move on…Great Stuff!

But it sure took you long enough to get here! Where ya been? Are Ms Margarita and Dr Cuervo over there? They have not yet shown up here today and there’s plenty of football games to watch. :margarit:

Busy…sorry…working on a new power point presentation for a whole new series of electrical classes…and working on my DVD editing of a full electrical inspection walk around.

Awesome stuff guys!
Here are a few electrical questions as i am waiting for West Michigan to have an electrical seminar to ask my 100 questions.
If you come across a home with the old 2 wire system and no ground, how do you call out recommendations if they ask?
Like if the Fridge or Living room for TV or computer room, well any high watt appliance plugged into wall. Do you tell them to add GFCI or do you say surge protector or both or do you just what?
I just googled the GFCI and Surge combo and that is pretty sweet. I have seen the ones with multlple plugs but not the single plug but maybe i haven’t looked hard enough.
Appreciate the guidance!
Andy B

I try and stay away from giving my openion on how they get it fixed .
If I give my advice and they have another electrician come in then they can say well Roy said this is what we should do .

“Ungrounded outlets recommend upgrade by qualified person.”

Usually when this is found there are many more concerns in the home and the complete system needs to be upgraded.
Example too small a service usually over fused many two prong receptacles. .
In this case I
"recommend complete electrical upgrade throughout by qualified person "

Roy Cooke

Also, If I ever saw a fridge or freezer pluged into a GFCI I would recommend that it NOT be plugged into a GFCI. If it trips out all the food is gone to waste.

I like Roy and George, or at least the recommendations in the above two posts. :margarit:

Something to think about if a refrigerator trips a GFCI protected device or circuit.

There may be something wrong with the refrigerator, something that may cause a shock or even electrocute someone… don’t you think that it is worth the tripping of this circuit if that is true.
Don’t be too fast to judge a GFCI device/circuit that is protecting an appliance or appliance circuit. Especially with todays new devices and the change in standards that appliances are wired to today. An appliance is only permitted to have 1/2 of 5 miliamps of leakage current… way too little to trip the GFCI. So…if a GFCI trips, be careful, as the appliance may have malfunctioning wiring.

I’m now using a desktop surge protector power strip but don’t know whether it is built-in GFCI . How can I tell whether it is GFCI protected?

If the power strip has GFCI protection built - in, it will have a “Test” button and a “Reset” button on it. If the receptacle that it is plugged into is GFCI protected, you can test it using a simple device

May I ask what has you searching questions that were asked in 2006?


Probable spammer.

C’mon man… if you don’t know the difference between a GFCI device and a surge protector… this may not be the career for you. Trying to keep this thread useful… I found something I have never encountered today. A CPD, specifically labeled as not acceptable as a GFCI used as a pool equipment breaker .