what is the difference?
Hmmm.
Different terminology.Does there need to be a difference?
I suppose a spike could mean a big drop.
A spike is generally considered a very short duration increase in voltage, i.e. maybe on the order of nanoseconds to microseconds long. A surge on the other hand, is of a longer duration, i.e. lasting milliseconds or longer. Here’s a depiction of a spike:
I suppose if you had to define the difference it would be the duration of the problem. A spike would be a short duration transient like you get from lightning or switching transients and a surge would be something that lasted longer like a crossed utility line that brought higher voltage until the fault cleared.
That would be inventing a definition though.
Makes sense.
What brings the question?
thank you all for your replys. I was at a safety meeting and we were talking about GFCI’s and the question was thrown out as a quiz. The winner gets a hat. I’ll let you know if I win.
Again, thanks
Spike - One NanoSecond
Surge - Three or More NanoSeconds…
Both can cause issues …really the difference is the duration.
What do you call two NanoSecond… a spurge??? 
Beat me to it.
lol…trust me…if it is a spike it will probably be (1) nanosecond or even less…if it is a surge…it will last longer…so basically (1) or less a spike…(2) or more…a surge…equals…Nasty Stuff…
Get your SPD’s Today…
Years ago I would occasionly have to rent a printing line voltage monitor to troubleshoot glitches in the supply to Cat Scan unit in the hospital I worked in. Back then you would end up with many feet of paper tape to review and look for anomallies.
see now…I would get a KICK out of looking at that…see this is why I want to leave my little PO-BUNK town…I dont get to experience stuff like that…lol…neat stuff like that I like…
It was fun at the time. It was less fun to report when no probelms were detected.
kinda like sitting waiting for a ghost…and nothing shows up…yeah…happens to the Ghost Hunters all the time.
While working for my past employer we had some spike problems with a plant down the road… They seemed to be coming consistent and it was something on the power company’s end.
Paul, have you seen any reducing transformers throw spikes when they are failing?
I would say spikes that we worry about are usually quite a bit longer than a nano second. The one in Mike’s scope picture looks like about 2ms, about what I am used to seeing for a switching transient on a line voltage circuit. It takes a heluva scope to even see a 1ns pulse and old TTL logic probably wouldn’t see it at all. “Spikes” are usually microseconds to milliseconds. A surge lasts several cycles at 60hz.
But again we are putting a definition to a term that is basically undefined across different diciplines.
You do have very high frequency transients too but they are the easy ones to filter out. I have heard engineers say an overhand knot in the power cord is enough to filter out those sub microsecond spikes. That is also the function of the .001uf capacitor across the multi uf filter capacitor on a power supply. It grabs the small stuff the bigger capacitor can’t see (in laymen’s terms)
Mike I stil have a Dranitz 626 in my shop. I can set the threshold on it so you don’t use too much paper and only see the spikes you want to but I have also had the experience of running out of paper when the problem goes on for a while.
Yep that sounds very familiar.
That is not the “good” Dranitz with all the bells and whistles but it will get the job done. It was a parting gift from IBM when I retired. All I had to do was run it for them a few times when they got in trouble. For a while, everytime I saw them I got some more of my old test equipment.
ok old fella…just ow old IS Mr.Fretwell…lol