Tired microwave?

[Badly Shaved Monkey]

Can someone with a physics/engineering brain tell me whether microwaves lose their oomph over time? Mine is 18 years old and I don't think it is as powerful as it used to be. Is there a simple experiment I can do to test it e.g. put in a known volume of water and measure how long it takes to boil?

Its nominal power is 600W.

[MRC_Hans]

Yes, a microwave will loose output over time. The heart of a microwave oven is a magnetron. A magnetron is a (highly specialized) type of vacuum tube. That may not say so much to modern people, but vacuum tubes have a limited life-span. I suppose you could test the output by letting it heat water, but presumably, you don't have any previous reference for its ability to heat water. The rated power is always the power fed to the magnetron, and that will probably not change. It just gets less efficient.

An 18 year old microwave oven is ancient. Not only will it be less efficient, it will also be leaky, meaning that it spills energy all over the place, making it potentially unsafe :boggled: . Replace it. It's not like new ones are expensive, these days.

Hans

[kmortis]

Yes, a microwave will loose output over time. The heart of a microwave oven is a magnetron. A magnetron is a (highly specialized) type of vacuum tube. That may not say so much to modern people, but vacuum tubes have a limited life-span. I suppose you could test the output by letting it heat water, but presumably, you don't have any previous reference for its ability to heat water. The rated power is always the power fed to the magnetron, and that will probably not change. It just gets less efficient.

An 18 year old microwave oven is ancient. Not only will it be less efficient, it will also be leaky, meaning that it spills energy all over the place, making it potentially unsafe :boggled: . Replace it. It's not like new ones are expensive, these days.

Hans

Yes, I'd bring a NARDA meter home from the office to measure the emissions first. Of course, I'd do that cause I'm a geek and have access to such equipment. For you, I'd jut suggest that you follow Hans's advice and buy a new one.

[Starthinker]

First, you have to get a new 600w microwave oven, as similar to yours as you can get, and set it next to yours. Next, put a kitten in each one. If they were the same then the kittens would explode at the same time, however, you will probably notice the kitten in the new oven would explode much quicker and more efficiently than the old one.

[Beady]

First, you have to get a new 600w microwave oven, as similar to yours as you can get, and set it next to yours. Next, put a kitten in each one. If they were the same then the kittens would explode at the same time, however, you will probably notice the kitten in the new oven would explode much quicker and more efficiently than the old one.

Alternatively, try heating a cup of coffee or popping a bag of corn. Either one would be a lot less messy and revolting.

[Badly Shaved Monkey]

An 18 year old microwave oven is ancient. Not only will it be less efficient, it will also be leaky, meaning that it spills energy all over the place, making it potentially unsafe :boggled: . Replace it. It's not like new ones are expensive, these days.

Yes, but that's no fun.

I'd still like an experimental basis for making the decision. Any volunteers for a race to boil 500ml water?

[andro]

On the subject of microwaves, how dangerous exactly is a leaky one? I once saw a bit of smoke or steam coming out of the door of mine and told my parents to bin it, but they still havent.. that was months ago.
Oh and i would advise against heating water in one.

[steenkh]

And, on the subject of leaking microwave ovens, how come that they get more leaky with time?

[andro]

And, on the subject of leaking microwave ovens, how come that they get more leaky with time?
because when the door has been opened and closed thousands of times the seal becomes imperfect, i guess.

[Roboramma]

Oh and i would advise against heating water in one.Why?

[andro]

Why?
en.wikipedia.org/wiki/Superheating
In physics, superheating (sometimes referred to as boiling retardation, boiling delay, or defervescence) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. This can be caused by rapidly heating a homogeneous substance while leaving it undisturbed (so as to avoid the introduction of air bubbles at nucleation sites).

Because a superheated fluid is the result of artificial circumstances, it is metastable, and is disrupted as soon as the circumstances abate, leading to the liquid boiling very suddenly and violently—a very dangerous situation. Superheating is sometimes a concern with microwave ovens, some of which can quickly heat water without physical disturbance. A person agitating a container full of superheated water by attempting to remove it from a microwave will likely be scalded.

[richardm]

Why?
Something to do with superheated steam forming under the surface, perhaps?

http://www.phys.unsw.edu.au/~jw/superheating.html (http://www.phys.unsw.edu.au/%7Ejw/superheating.html)

Edit: Beaten!

[kmortis]

because when the door has been opened and closed thousands of times the seal becomes imperfect, i guess.

YEAH!!! Finally a question in my field.

Yeah, proper shielding requires good metal-to-metal contact (ok, if you have an exotic conductive polymer, that'll work too, but those are expensive). As time goes on, obviously, the repetitive opening and closing of the door a) allows the metal to oxidize, therefore compromising the conductivity and b) generally breaksdown the metal itself (ie cracks form).

[Badly Shaved Monkey]

en.wikipedia.org/wiki/Superheating
In physics, superheating (sometimes referred to as boiling retardation, boiling delay, or defervescence) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. This can be caused by rapidly heating a homogeneous substance while leaving it undisturbed (so as to avoid the introduction of air bubbles at nucleation sites).

Because a superheated fluid is the result of artificial circumstances, it is metastable, and is disrupted as soon as the circumstances abate, leading to the liquid boiling very suddenly and violently—a very dangerous situation. Superheating is sometimes a concern with microwave ovens, some of which can quickly heat water without physical disturbance. A person agitating a container full of superheated water by attempting to remove it from a microwave will likely be scalded.

OK, so stir the water first.

We're never going to crack the problem of fusion if we're all too chicken to reheat our coffee in the microwave.

[casebro]

We're never going to crack the problem of fusion if we're all too chicken to reheat our coffee in the microwave.

Yes, but the REAL challenge is COLD fusion, so should we stir the Hydrogen?

[CurtC]

You can solve the problem of superheating by placing something in the bottom of the container. You need anything that's not smooth like the ceramic bowl is. When I boil water for my oats, I place a couple of oat slivers into the water at the beginning to give it some nucleation sites and avoid superheating.

By the way, if you want to do the time-to-boil-water experiment, you would need to do this anyway in order to correctly compare the times. Also, shouldn't you be able to take the time and caluclate watts? Let's see here - typing "1 calorie per second in watts" into Google yields 4.184 watts, and 500 ml of water should take around 39,000 calories to boil, so a 600-watt oven should take 270 seconds to boil, or 4.5 minutes.

Hey, 22 years since getting out of college and I can still do this!

[casebro]

YEAH!!! Finally a question in my field.

Yeah, proper shielding requires good metal-to-metal contact (ok, if you have an exotic conductive polymer, that'll work too, but those are expensive). As time goes on, obviously, the repetitive opening and closing of the door a) allows the metal to oxidize, therefore compromising the conductivity and b) generally breaksdown the metal itself (ie cracks form).

I didn't realise that reflectors have to be grounded to work- won't the door still reflect the waves back into the oven, grounded or not? My current oven has a "labyrinth " seal, the door is recessed into the cabinet, so the waves can't get past the metal? But if it sufferes from leakage, what percent could get out the door? My oven has 1,000 square inchs, the seal could only be 6 square inchs, less than 1% enegy escapes? Would it ever be enough to cause a detectable loss in heating ability?

I'd guess that magnetrons age, but isn't it more likely that the contacts in the relay are corroded and resistive?

AND, a related WOO/radar query, I recently remodeled a kitchen. It had an ancient microwave oven, so old it had a FCC license to the old owner. Late 50's? The walls had a wire run back and forth under the drywall. Was it to prevent 'transmission' of radar from the oven, or was it to prevent 'beams' from outerspace?

[CurtC]

But if it sufferes from leakage, what percent could get out the door? My oven has 1,000 square inchs, the seal could only be 6 square inchs, less than 1% enegy escapes? Would it ever be enough to cause a detectable loss in heating ability?

Since the microwaves reflect off the metal surfaces that make the chamber, pretty much all the energy will go out whatever hole is there if there isn't something inside the oven to absorb them first. Also, the hole has to be large enough to let the waves pass through. I've read (and I'll look for the cite) of someone trying to detect microwaves leaking out of old oven seals, and was able to detect none except in the cases where the door was about to fall off its hinges. 2.4 GHz waves are just too big to fit out of little cracks.

AND, a related WOO/radar query, I recently remodeled a kitchen. It had an ancient microwave oven, so old it had a FCC license to the old owner. Late 50's? The walls had a wire run back and forth under the drywall. Was it to prevent 'transmission' of radar from the oven, or was it to prevent 'beams' from outerspace?If this was so old that it required an FCC license, my WAG would be that it was to keep any stray waves from passing through the wall and interfering with public communications.

[CFLarsen]

A magnetron is a (highly specialized) type of vacuum tube.

Sounds like a Marvel superhero to me.

"Magnetron".

[CFLarsen]

Yes, but that's no fun.

I'd still like an experimental basis for making the decision. Any volunteers for a race to boil 500ml water?

Tsk, tsk. Wimp.

Any volunteers with pacemakers to stand in front of a leaky microwave?

[Bronze Dog]

Sounds like a Marvel superhero to me.

"Magnetron".
Wrong!

http://pokemon.tcgplayer.com/tcg/scans/skyridge/h18%20magneton.jpg

[kmortis]

Since the microwaves reflect off the metal surfaces that make the chamber, pretty much all the energy will go out whatever hole is there if there isn't something inside the oven to absorb them first. Also, the hole has to be large enough to let the waves pass through. I've read (and I'll look for the cite) of someone trying to detect microwaves leaking out of old oven seals, and was able to detect none except in the cases where the door was about to fall off its hinges. 2.4 GHz waves are just too big to fit out of little cracks.

Yeah, the wavelenght of a 2.4 GHz wave is 8 cm (l=f/c), so even a quarterwave slot would have to be at least 2 cm. Even still, the door will breakdown, but you probably don't have to wory that much, although that 2 -8 cm can be the lenght of the crack too (ie if the seal has lifted away from the door), but I wouldn't worry too too much about it, just don't stick your face (or other body part) right up next to it. According to the military exposure guidelines, at 2.4 GHz, you can be exposed to 8 mW/cm^2 for 6 minutes with no ill effects. I can't find the OSHA standard right now, but IIRC it's pretty close, if not the same (I know one borrowed from the other, I just odn't remember which way that was).

The fact that you're pi$$ing away money hand over fist to keep that old tube a'goin' would be enough to get me to buy new.


If this was so old that it required an FCC license, my WAG would be that it was to keep any stray waves from passing through the wall and interfering with public communications.

Not necessarily. The first interference requirments for the miltary (which predated the civilian side of the house) was in 1945 (JAN-I-225). My WAG is that since microwave came out of RADAR technology (gotta give props to Charlie Adams and Mr. Spencer), the FCC was concerned about civies having a RADAR tranmitter in their houses.
The wire could have been an attempt at a partial Faraday cage. If that's the case, then it would be more to shield the environment from the microwave, rather than the other way around. As I recall, there isn't really much you can do to a magnetron, espically one of those old Raytheon models.

[kmortis]

Wrong!

http://pokemon.tcgplayer.com/tcg/scans/skyridge/h18%20magneton.jpg

:dl:

[MRC_Hans]

On the subject of microwaves, how dangerous exactly is a leaky one? I once saw a bit of smoke or steam coming out of the door of mine and told my parents to bin it, but they still havent.. that was months ago.
Oh and i would advise against heating water in one.Steam is not a problem, no microwave oven is air-tight. The problem is RF energy leaking, and the dangers are burns. A good idea is never to have any portion of your body close to a MW oven (when in operation), especially not an older one. The burns can be quite serious, because they are deep, and because your ability to sense heat is situated in the skin. The microwaves heat the deeper tissues, and by the time the heat is sensed in the skin (which is heated less because it is less conductive), you might be well-cooked a couple of centimeters in :eye-poppi . There is also some apprehension about possible long-term effects of exposure to lower power levels, but no conclusive evidence exists, and unless you use your MW oven several times a day, this is not likely to be a serious concern.

And to Steen: Old ovens get leaky for several reasons.

- Door hinges wear, so the door might not fit as snuggly as designed.
- Seals wear out, change shape or oxidize.
- The cabinet developes cracks.

What it takes to leak microwaves is a slit in the enclosure that is more than a wavelength long (a couple of cm). The slit can be almost microscopic in thicness, the imortant part is that it is non-conductive. A non-conductive slit acts like a transmitting antenna and propagates the microwaves to the outside world.

Finally BSM: I should really not need to tell you about the importance of a reliable reference. Obviously, the only relevant reference would be a new (or at least unused) MW oven of the same make and model as your old one. I could boil some water in mine (what starting temperature are you expecting, btw.?), but it's an 800W and will outperform yours even though rather old, too.

The position of the container will also make a difference.

What you CAN do is buy a new oven, and compare it with the old one. That will give you a nice feeling of having spent your money well ;).

Hans

[steenkh]

Most microwave ovens have rotating tables so that should take care of possible over-heating (My oven has a rotating antenna).

And thanks for the explanations!

[Mojo]

What you CAN do is buy a new oven, and compare it with the old one. That will give you a nice feeling of having spent your money well ;). Unless, of course, the new one doesn't perform any better than the old one...

[MRC_Hans]

It will, because at he very least it will have more power. They don't make 600W any longer. Also, it will probably have more bells and whistles. And it probably won't last another 18 years ;).

Hans

[kmortis]

It will, because at he very least it will have more power. They don't make 600W any longer. Also, it will probably have more bells and whistles. And it probably won't last another 18 years ;).

Hans

That's true. I used to work for Raytheon. We had some of the earliest commercially available Amana Radar-Range microwaves. These things were only slightly smaller than our desks, and about 600 - 800 W. They were circa 1975. Obviously, being EMI guys, we were a touch concerned about the age of these things, so we took our lil NARDA meters down to them, put in a cuppa water, and set it for 3 minutes (yes, in fact, we did have the skewer in the cup). These things were built like brick sh**houses. We got a slightly higher reading (I don't remember now what the actual levels were, this is about 4 years ago) around the seams of the door, but not enough to trip the alarm on the meter (IOW, it wasn't above the PEL set by OSHA).

I wouldn't keep a microwave around that long any more. TBPH, even with that experiment, I never really felt comfortable standing around those old ones either. Of course, that could have been from the garbage can sitting next to them as much as the age of the units.

[MRC_Hans]

BTW, BSM: If you are a tinkerer, you WILL want to scrap your old MW. There's a magnet in there that rocks. It's the type of magnet that can lift a ballpoint pen by the ball (provided it's a steel ball).

Hans

[CFLarsen]

Wrong!

http://pokemon.tcgplayer.com/tcg/scans/skyridge/h18%20magneton.jpg

Close enough.

[CurtC]

Here's some more to read: Microwave Ovens FAQ (http://rabi.phys.virginia.edu/HTW/microwave_ovens.html)

[Badly Shaved Monkey]

BTW, BSM: If you are a tinkerer, you WILL want to scrap your old MW. There's a magnet in there that rocks. It's the type of magnet that can lift a ballpoint pen by the ball (provided it's a steel ball).

Hans

Ah, now that is useful information. The kids will love it.

BTW the main reason for not replacing it is laziness because it's not just any old microwave it's a combo one with a very big interior and it's been more effort than I can be bothered with to search out a good replacement instead of waiting 30 secs longer for my soup!

[CurtC]

Oh, and from the FAQ I linked to above, there's this:I've measured several ovens and have only found one that leaks a measurable amount of microwave power. That leaker is an oven that I've used in countless demonstrations and have taken apart several times (it appears on page 514 of my book). Considering the abuse that poor oven has had, it's doing pretty well. At a talk I gave yesterday, I couldn't get it to leak more than about 1 mW/cm2 even though I was measuring microwave power directly on the edge of the oven door--the most vulnerable point in the oven. Given that this oven's door sags several millimeters as the result of its rough treatment, that's not bad. In short, I doubt that there are many leaky microwave ovens around that haven't been dropped, crushed in shipping, or otherwise suffered serious mechanical injury.

[Johnny Pneumatic]

en.wikipedia.org/wiki/Superheating
In physics, superheating (sometimes referred to as boiling retardation, boiling delay, or defervescence) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. This can be caused by rapidly heating a homogeneous substance while leaving it undisturbed (so as to avoid the introduction of air bubbles at nucleation sites).

Because a superheated fluid is the result of artificial circumstances, it is metastable, and is disrupted as soon as the circumstances abate, leading to the liquid boiling very suddenly and violently—a very dangerous situation. Superheating is sometimes a concern with microwave ovens, some of which can quickly heat water without physical disturbance. A person agitating a container full of superheated water by attempting to remove it from a microwave will likely be scalded.

That's only a problem if you boil distilled water. You don't use distilled water do you? If so, pansy; lead never hurt anyone.

[c4ts]

Sounds like a Marvel superhero to me.

"Magnetron".

A tank that levitates buildings and vehicles with beams of electromagnetic force comes to mind...

[andro]

That's only a problem if you boil distilled water. You don't use distilled water do you? If so, pansy; lead never hurt anyone.
amasci.com/weird/microexp.html#myth damn this no links rule
scroll down a bit

[Hamradioguy]

There's always the option of simply replacing the magnatron. I did that with my microwave oven a few years ago. But then it was a top of the line convection oven and the cost of the tube and doing the replacement myself made sense.
Unless you are really enamoured of this unit it might be time to just replace it. Hey, we all go through this with our old cars you know.....
BTW- I recall seeing a really old microwave (Amana?) oven for sale at a hamfest back in the 1970s. The thing was the size of a desk and had a water cooled HV transformer. A real museum piece.

[Soapy Sam]

Mine's a Brother- 800W I think (I'm not at home). I bought it in 1983 and it works as well as ever. I know because the timer is mechanical and has a worn notch at the setting I use to boil a mug of water. 3 minutes, nearly to the second and I never scalded myself yet. (Like BSM I give it a good stir before starting and the first thing I add after it boils is milk.) I do check the door seals regularly, which seem to be in perfect shape. I really don't want to replace it, as current models tend to be either much smaller, or significantly larger.
Apart from fancy detectors, Hans, is there a breadboard way to test for leakage? Popcorn taped to the hinges for instance? Would it interact with a wifi router modem in any measurable way?

[CaveDave]

According to the guys who travel around doing repairs for the chain-type convenience stores, their commercial ovens lose power from being frequently overloaded. Seems the magnets lose strength because of the high currents during overloads, just like PM DC servomotors will demag if overloaded. The tubes then become diodes sinking the current (making heat) rather than generating RF.

Dave

[MRC_Hans]

Mine's a Brother- 800W I think (I'm not at home). I bought it in 1983 and it works as well as ever. I know because the timer is mechanical and has a worn notch at the setting I use to boil a mug of water. 3 minutes, nearly to the second and I never scalded myself yet. (Like BSM I give it a good stir before starting and the first thing I add after it boils is milk.) I do check the door seals regularly, which seem to be in perfect shape. I really don't want to replace it, as current models tend to be either much smaller, or significantly larger.
Apart from fancy detectors, Hans, is there a breadboard way to test for leakage? Popcorn taped to the hinges for instance? Would it interact with a wifi router modem in any measurable way?Well, how long they last depends on how often you use them, of course. I only use mine very occasionally, so it is in for a long life.

How to check for leaks? Well apart from using sophisticated instruments, I suppose you could make an old-fashioned radio-ham "RF sniffer": Get some enamel isolated copper wire (thickness is unimportant, but around gauge 32 is practical), make a small coil about half an inch in diameter and 10 windings. If the wire is thick enough, it can hold itself, otherwise, fold a piece of duct-tape around it to hold it in place (leave the wire-ends sticking out). Connect it (preferably by soldering) to a 1,5V flash-light bulb.

Now, fire up your micro oven (put something in there that takes a while to heat, you could take the opportunity to cook some potatoes), and hold the coil close the door-edges and corners. If the bulb lights up in any position, you have a leak that is serious enough to need repair.

Hans

[Dave_46]

Re testing.

I think I heard a long time ago that a portable FM radio could be used. Wave the aerial around the unit and listen for white noise.

Dave

[kmortis]

Well, how long they last depends on how often you use them, of course. I only use mine very occasionally, so it is in for a long life.

How to check for leaks? Well apart from using sophisticated instruments, I suppose you could make an old-fashioned radio-ham "RF sniffer": Get some enamel isolated copper wire (thickness is unimportant, but around gauge 32 is practical), make a small coil about half an inch in diameter and 10 windings. If the wire is thick enough, it can hold itself, otherwise, fold a piece of duct-tape around it to hold it in place (leave the wire-ends sticking out). Connect it (preferably by soldering) to a 1,5V flash-light bulb.

Now, fire up your micro oven (put something in there that takes a while to heat, you could take the opportunity to cook some potatoes), and hold the coil close the door-edges and corners. If the bulb lights up in any position, you have a leak that is serious enough to need repair.

Hans

Another quick and dirty RF detctor is an old transistor radio tuned to an AM station.

[kmortis]

Re testing.

I think I heard a long time ago that a portable FM radio could be used. Wave the aerial around the unit and listen for white noise.

Dave

FM doesn't work as well as AM because of the demodulation process.

[MRC_Hans]

An AM radio should pick up a distinct hum, but the problem is that it is quite sensitive, so you might get scared by a totally benign leakage. After all, we are talking about some 500W of RF power, just inside a small metal box. Some of it is bound to leak out. The idea of the coil/bulb device is that it will only react to emissions over a few hundred milliwatt.

Hans

[CurtC]

Now, fire up your micro oven (put something in there that takes a while to heat, you could take the opportunity to cook some potatoes), and hold the coil close the door-edges and corners. If the bulb lights up in any position, you have a leak that is serious enough to need repair.If you're getting enough leakage to light up a bulb, that would be a huge leak. In that FAQ that I referred to earlier, the worst he had ever seen was 1 mW/cm2. A milliwatt wouldn't make a bulb glow at all.

[kmortis]

An AM radio should pick up a distinct hum, but the problem is that it is quite sensitive, so you might get scared by a totally benign leakage. After all, we are talking about some 500W of RF power, just inside a small metal box. Some of it is bound to leak out. The idea of the coil/bulb device is that it will only react to emissions over a few hundred milliwatt.

Hans

True. However, it takes mush less technical skill to plug an AM radio into a wall than to breadboard the coil/bulb, n'est pas? Besides, if all you're trying to do is see if there is any, it's a good, cheap, dirty way of doing so.

You can correlate the distance from the box to field strenght, tho. If you're across the room and the program you've been listening to becomes total uncorrealtable noise when the uwave comes on, then you might have an issue, time to construct that coil (or find your nearest friendly neighborhood EMI guy and ask him to bring over his NARDA). If, OTOH, you have to get the silly thing sitting on the door to hear the slightest fuzz, then you should probably get yourself a new hobby other than RF detection.

Either way, always remember the first rule of RF testing....never lick a live transmitter/transmit antenna.

IEEE puts out a book called "Testing for EMC Compliance" (http://www.amazon.com/exec/obidos/tg/detail/-/047143308X/qid=1129727132/sr=8-1/ref=pd_bbs_1/102-5534972-4174547?v=glance&s=books&n=507846), in one of the appendicies there's a list of cheap and easy recievers listed.

[Dave_46]

FM doesn't work as well as AM because of the demodulation process.

I sit corrected.

Dave

[MRC_Hans]

If you're getting enough leakage to light up a bulb, that would be a huge leak. In that FAQ that I referred to earlier, the worst he had ever seen was 1 mW/cm2. A milliwatt wouldn't make a bulb glow at all.True. I was talking about safety, not EMI. 1 mW/cm2, or even 100 mW/cm2 won't hurt you. But it might mess up your radio reception.

Hans

[kmortis]

True. I was talking about safety, not EMI. 1 mW/cm2, or even 100 mW/cm2 won't hurt you. But it might mess up your radio reception.

Hans

(psst...Hans...EMI and safety can go hand in hand. It's why I have to deal with HERP {Hazards of Elecromagntic Radiation on Personel} on a regular basis. but I do understand your point)

[MRC_Hans]

(psst...Hans...EMI and safety can go hand in hand. It's why I have to deal with HERP {Hazards of Elecromagntic Radiation on Personel} on a regular basis. but I do understand your point)Sorry, I disagree. The energy levels relevant for safety and those relevant for EMI are several orders of magnitude apart. But of course, if you don't have an EMI problem, you won't have a safety problem. (Still strictly talking microwave ovens)

Hans

[kmortis]

Sorry, I disagree. The energy levels relevant for safety and those relevant for EMI are several orders of magnitude apart. But of course, if you don't have an EMI problem, you won't have a safety problem. (Still strictly talking microwave ovens)

Hans

Agreed. The safety levels were set so low that there was no chance in Neifleheim that anyone could even think about being harmed, if the proper protection was in place. Whereas EMI is to protect equipment which can be interfered with, just a little, with no ill effects....hopefully.

Let's not talk about ESD and Lightning protection tho. ;)

[Soapy Sam]

Cheers chaps. Sounds like a fun way to pass a wet hour. I should be home on Saturday, I'm pretty sure there's some enamelled wire in the garage.
[Big kid mode]
I like silly stuff like this.
[/Big Kid]