Filtered power for test equipment or not really needed? - Page 1
Forum section: electronics / testgear

author: rrinker
author_rank: Super Contributor
timestamp: February 12, 2016, 04:33:09 am
content: So when I build my new bench, I want to integrate some sort of power distribution so as to not have cords all over. Is it worth it to go with a filtered surge protector such as the IsoBar type, or is that just overkill? I'm not running 7.5 digit equipment here, so far what I have is a Siglent SDS1102CML scope, a Fluke 45 multimeter, and a Fluke 8012A meter. Only other thing I can see adding for the foreseeable future is a power supply of some sort. Will using the filtered power strip give me any benefit along the lines of less power line noise affecting the equipment, or should I just spend my money elsewhere? They aren't inexpensive, and used is not really something I want to mess with, although as mentioned in another thread, about the only thing that would normally wear out would be the MOVs and they can be replaced easily enough, but you have no way of knowing if a used one has maybe been hit with a good solid strike and just had the MOVs replaced or what. I used to have a small one with a remote turn on switch, but that seems to have gotten lost a couple of moves ago, or I could just try it out and see for myself. I'm sorta leaning towards the idea that the equipment already has decent enough noise filtering built in and the extra really wouldn't do much, but I've been known to be wrong.

author: tautech
author_rank: Super Contributor
timestamp: February 12, 2016, 06:41:55 am
content: Quote from: rrinker on February 12, 2016, 04:33:09 amI'd be more concerned with protecting your valuable equipment from nasties in the mains as unless you go to some trouble the workbench can be quite a noisy environment from lighting and the various SMPS we all use. So yes go for it.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: February 13, 2016, 07:43:50 pm
content: Why not, its good to have a master switch to power off the workbench anyway (tons of modern stuff draws quiescent current in wasteful amounts).As for the filtering, it's also not a terrible idea. No manufacturer likes to spend money on things like Y capacitors and chokes, they just want to pass the tests.. and you don't want your equipment destroyed by shoddy power.Much better to have a MOV inside of a dedicated surge protector pop then have to take apart equipment and hope that its not filled with smoke/mov guts/etc. Alot of those inline IEC filters tend to fail in nasty ways too, so shunting the noise/transients away with a better protector is not a bad idea.I would actually spend a little extra here. If you end up getting alot of expensive equipment the better protected it is the easier you will sleep.Like if you have a extremely cheaply made IEC filter module, the less energy that gets dissipated or shunted means the components are running with less stress, meaning it will last longer/indefinitely.

author: uncle_bob
author_rank: Unknown
timestamp: February 13, 2016, 07:56:59 pm
content: HiI've seen a lot of benches over the years. The first thing to make sure of is *really* stupid. Make sure all the grounds outlet grounds are hooked up nice and solid. Second is don't wire the bench for 220V an split it at the bench. Pick one phase and use that. If you have 220V stuff that you must power, don't try to balance the rest of the stuff on both sides of the 220.Next up on the list is still in the silly arena. Think about where the outlets are and what can drop into them or slide into them. Many years ago, the place I worked had a standard bench with outlets right along the front edge. Quick to plug stuff into. Lots of fun with loose wire solder and hitting an outlet. Not easy to do. Even harder to believe until you watched a guy do it three times in 15 minutes !!!Sort of off to on topic: Yes, filter the supply. Do it as well as you can. Consider how you will ESD protect the bench and where that ties in. At the same time you will be looking at equipment grounds. You want the whole bench to be as close to "same same" as you can. None of this costs much. It's more thinking it through and maybe a ground strap or two. Also consider the stuff that comes on to the bench. Things like computers may run all over the place. Ethernet is not usually a big issue. If the cable modem is on your bench ... that's a bit different.Fun !!Bob

author: TheSteve
author_rank: Unknown
timestamp: February 13, 2016, 08:12:03 pm
content: After proper grounding I'd be concerned about ethernet myself. I have seen damage from a nearby lightning strike a few times now and the damaged items were always connected to the phone line or cable connection directly or through the network. All of my bench gear is networked via an old router reprogrammed to operate in bridge mode so there is no direct connection to a phone or cable line. This also applies to my amateur radio gear which is connected to a tower mounted antenna.

author: amirm
author_rank: Regular Contributor
timestamp: February 13, 2016, 08:38:21 pm
content: If you care about lightning protection, the proper solution for that is at the meter/entrance to your property. That is where you have a proper ground to shunt the surge to earth. Putting a power strip way past that will do nothing as it will have a high impedance path to ground.Easiest way to get protection at the meter is to have your electric company install one. They are not the best devices but are cheap. In our neck of the woods for $300 the power company will do that.As for filtering, the power strips will only do that at very high frequencies.In other words, don't waste your money. Just get a power distribution you like and don't worry about filtering/surge protection at the bench.

author: rrinker
author_rank: Super Contributor
timestamp: February 13, 2016, 08:43:21 pm
content: After thinking about it, I went looking at options. And I found they still make the one with the handy remote switch like I used to have. Also it has the additional feature that when the MOVs reach end of life, it stops working, rather than letting you continue on thinking your gear is protected. Downside is 8 outlets instead of 12 on the other unit, but I could buy 2 of the remote switch units for the price of the one - which I will be doing anyway since one half of the bench will be electronics and the other leg (it's L shaped) will be for modeling and have things like Dremels plugged in. There are conveniently two outlets, unfortunately on the same circuit though. I COULD change that later on when I redo the basement.I was planning to put the power at the back of the bench, not at the front where stuff can fall in the outlets. Mount the control switch under the front edge off to one side where I won't accidently bump it with a knee. Then I can be sure everything on the bench is powered off when I step away - the switch IS a lighted type so it's obvious, too.Computer will go through it's own surge protector, though it's all the same circuit back to the main breaker, again. This is just a room in my house, this isn't a commercial production lab I'm setting up or anything, simply hobbyist experimentation type stuff. I need some sort of power distribution so I figured why not get one that has EMI/RF filtration as well as surge protection.Ethernet side of the computer will be multiple devices away from the cable line, I can always get a power strip that offers Ethernet surge protection as well as AC, but I don't have any on my other computers, just power line surge. Yeah, I've seen power surges come in via other methods and blow things up, so it might be worthwhile, I've been lucky for too long.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: February 13, 2016, 08:50:20 pm
content: Protection IS a good idea because the MOV's in the power strip will burn out not the movs inside of the equipment you have. Easier to repair and less chance of the actual equipment being damaged by something like a exploding MOV!I once had a lightning strike near my house (dangerously close) that fried all equipment connected to the LAN network.I don't know if the EM potential was induced outside or along the entire length of my cables (like in my house), so I don't know if any protection could have helped (other then running the LAN network at a lower impedance). The router and all LAN cards on my computers got fried, however i did not have any test equipment at that time so I just replaced the NICs and it worked fine.I got a surge protector that has a LAN/Coaxial filter on it since then (so point protection), but I don't know if it would have helped. I imagine protection at the inlet to the house would not have helped much?

author: uncle_bob
author_rank: Unknown
timestamp: February 13, 2016, 08:54:16 pm
content: HiRather than try to do everything with one gizmo, get some of these:http://www.homedepot.com/p/Tripp-Lite-8-Outlet-Vertical-Power-Strip-with-15-ft-Cord-PS2408/203345744?MERCH=REC-_-PIPHorizontal1_rr-_-202320916-_-203345744-_-NThey aren't exactly cheap. There other places to buy them or something similar. With no MOV's or other silly stuff inside, they last pretty much forever. By spreading the outlets out along the back of the bench, they make cable management much easier. With a single outlet to plug it all into, a lot of the other stuff does not make much sense. For protection plug the whole empire (hobby stuff etc) into a single protector. Also consider that a breaker box mounted protector may be a better thing than local MOV's.Bob

author: TheSteve
author_rank: Unknown
timestamp: February 13, 2016, 09:11:32 pm
content: One of the lightning strikes near me was to a tree across the street. The phone line running down the wall in my shop flashed brightly, the phone that was connected to it was destroyed and the phone line itself was open circuit afterwards. A TV had its inputs damaged, a computer had its network and usb ports damaged. End of the day only items connected to phone/cable lines suffered immediate failure so that is where I will continue to concentrate my efforts. If there is a direct lightning hit no amount of protection will save everything so I figure simply removing as many hardwired connections as possible to outside sources is the easiest way to go.

author: uncle_bob
author_rank: Unknown
timestamp: February 13, 2016, 09:48:59 pm
content: HiOne of the interesting things about lightning is that it most certainly can strike twice in the same area. If you live in the big tall house over there on top of the hill, you may have a lot of experience with strikes and near misses. Poor old Bob (yea, right ) living in his cave in the valley has a lot less direct experience. Of course Bob may not be very happy when the flood waters come rolling along.No two sites are going to be quite the same in terms of lighting risk. If you have had an event, it is a good bet you will have another. Taking precautions is a good idea. If you have lived in the same house for the last 50 years and never had anything come close, you may not have to be quite as careful. It's an odds thing, you can never be *sure* in either case. It is prudent to play the odds.The other set of gotchas actually have noting directly to do with lightning. For quite a while we had a flakey ~100 KV distribution line feeding the local sub-station. While you would *think* that would have little impact on the spikes and hits on my local line ... it most certainly did. The power is a lot cleaner now that they had to replace the crap line. Sometimes tornados are a good thingNothing ever was in the "trip all the circuits" range. It certainly was not what you wanted for a clean bench supply. At one point I think we had well over a dozen UPS's running just to keep from having to reset / unplug / reboot things all the time.Bob