Surge Protection Devices - Part 1

A series on surge protection. In part 1, what are surges, where do they come from, and what kind of damage can occur to unprotected installations.

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[chrisholmes]

I wish you’d been one of my teachers at school. Clear, engaging, and clearly invested in your subject. Superb.

[stephenvjoseph]

I'm glad youtube recommended your channel. I get to learn something new each time I watch your videos. You are very well prepared and methodical in your explanations. Great Effort JW

[seanpassant]

Thanks John, this is a great video, really helpful to explain the use of and requirement for surge protection. Very few people really realise the true extent & cost of damage caused by over voltage issues, one reason for that is that the UK insurance industry is very tight lipped about these things. In Germany this is not the case the insurance industry makes information freely available and they suggest that from all claims of "electrical or electronic damage" over voltage / surge issues are responsible for 31% of the claims. That is a huge figure, for anyone reading this and thinking "he's an idiot, I've never seen anything like that level of damage" ....well how do you know? Over voltage damage is not always immediate and spectacular, there may not be a huge bang and plumes of black smoke. You can have several incidents over a few weeks and it would lead to wear and tear, then one day flick a switch on and the equipment doesn't work. Do you immediately think "oh that must be wear and tear fro over voltage events" of course you don't. You think "oh that's broken, more money to replace it /repair it". SPD's offer longer life spans for equipment, increased levels of availability, reduction in down time and less maintenance. They are like "electrical life assurance for equipment".

[mastergx]

I've known of two instances where lightning strikes have had a noticable effect. Back in the 90's I was watching the TV in a thunderstorm - suddenly all the lights "strobed" once and the tv went to standby. No damage, just had to turn the tv back on. The second, much more recent incident was during a particularly powerful thunderstorm - a friend of mine's Router and computer motherboard got fried (I diagnosed the computer and figured out it was just the motherboard that bought it). I think this is a good example of what John is talking about here.

[PandauL]

the best english electrician on youtube :D

[rossmurdoch]

Another clear explanation showing what these things are, and why they now an important addition, thanks John

[boolve]

After some time watching various sparky channels on YouTube I will honestly say that your channel is most informative or/and pleasant to listen. Thank you.
Negative comments I may write in private some time later on.

[webwolfy]

Two years ago almost all the plugged in devices with circuit boards inside them all died in the same week, I always knew it was a surge but now I finally understand why. Thanks!

[jamesdyas]

Excellent videos thanks. I rewired a property following a direct lightning strike some years ago. It hit an extension part of the property and more or less demolished it. If there was anybody in at the time it could have been serious. 2.5 mm and 6mm cables had been vaporised in places. Seemed to use everything it could as a path to ground. Open reach or British telecom were there for a few days doing street works.

[Istari_]

I knew a bloke called surge, he was French. I don’t believe protection was necessary as he was a great chap!
Your videos are excellent, possibly the best on here.
🕺🏽🍻

[colinhursell]

My kitchen had a mixture of fluorescent and incandescent lighting. I replaced the incandescent lamps with LED types and noticed that the LEDs were failing almost immediately. Finally it dawned on me that the failures were always coincident with switching the lights on or off. The only reason for this I could think of was that the chokes in the fluorescent fittings were causing a surge at switch on/off which was enough to damage the LEDs. I replaced all the fluorescent fittings with LED types and problem solved.


Not particularly surprising I hear you say. However, two things are worthy of note. LEDs elsewhere in the house of exactly the same type/manufacturer were not being damaged although they were on the same lighting circuit. I can only assume that the extra wiring length to these other LEDs had sufficient capacitance to suppress the surges being generated by the fluorescent fittings. The other thing I was surprised by was that the LED manufacturers (a well known brand) had never heard of this kind of issue before and moreover did not seem to be very aware in general of how sensitive their products were to what I imagine are fairly minor surges in the great scheme of things (assuming my theory was correct!).


Has anyone else encountered similar issues?

[antonyharding]

Hi John, . You explain things so interestingly and understandable for the non exspert, plus I love it when you go the hole way and let us see things burn out and set on fire..
Keep em coming John...
Regards Antony
Warrington Cheshire.

[camronyounis]

Whenever I need info on any electrical subject i check on YouTube if John Ward has made an info video on it, you are the god on electrical knowledge 😉

[sumilidero]

Most damage caused by surge I witnessed, was in the one of substations in a factory last summer. Surge (or few of them) busted the SPDs, but also busted electronics of a main circuit breaker and power analyzer. Later on, there was significant voltage drop that caused overcurrent, which resulted in melted 2500A busbars, because 2000A breaker didnt trip.

[robertmayberry]

great stuff. transient change of pitch of the voice always cracks me up

[andybarnard]

Most electronic devices have at least a token amount of surge suppression fitted. At the mains input you will often see a small (normally blue) disc called a metal oxide varistor connected across the supply input. These short out large spikes and have microsecond response times.

[showme]

Thanks John will share with family and friends!

[elonmask]

That was certainly good insomnia protection JW, just a quick correction, “high voltage transients” even those from direct strikes to overhead lines, don’t travel very far before they dissipate either by breaking down the air resistance and finding a path to earth, or the insulation between adjacent conductors and finding a path to neutral.

HV injections (where a cross arm breaks, or a car hits a pole and one of the hv lines falls onto the LV network below it), on the other hand can really do some damage, because the voltage is low enough to travel down the network without flashing over, and it will continue to flow until the protective device upstream operates (current X duration = let through energy), and that little 20Ka MOV arrester you have there will either be a god send if it is properly installed, or, what the fire brigade will later identify as “the seat of the fire”.

[DrGreenGiant]

Loving the big Clive style bridge rectifier symbol :) great video as always

[shaunsparky]

Thanks John, a very nice introduction to purpose and limitations of SPD's in general.
Aside transients caused by atmospheric (lightning) you highlight the need for awareness of 'Surge Creating' equipment along with 'Surge Sensitive'.