Lighting-proof your electronics (and home) - Page 1
Forum section: electronics / general

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 08:24:00 am
content: I just had a storm pass over which was fairly intense. Plenty of nearby lightning strikes, constant power issues etc... I'm a bit of a nerd so at home I have a full height server rack with some 4 servers (mixture of Dell and Supermicro) plus networking gear, which I've grown to be fairly dependant on. My pride and joy is my file server which contains absolutely everything (also backed up to tape). Most things are protected by a UPS, or so I thought...I just lost a power supply in my main file server. Turns out for some reason that particular PSU was connected straight to mains and after a rather loud crack, the server began screaming its head off. The remaining PSU connected to the UPS survived and is keeping everything running. For some reason I must have fiddled with the cabling and forgotten about it.This got me thinking, how do EE geeks protect their most valued gear (apart from the obvious solution of disconnecting it from mains). Do you rely on a UPS? Do you have other protection in place?(Dave: If you want the blown PSU for a teardown/repair, it's all yours. It still gets power but the LED remains orange and won't power up fully.)

author: BradC
author_rank: Super Contributor
timestamp: March 11, 2015, 08:55:41 am
content: Quote from: Halon on March 11, 2015, 08:24:00 amSecond hand APC SmartUPS on everything. I buy 'em, replace the MOV's and batteries and in they go. I have IT stuff distributed around the house, so the UPS goes in the garage and I have UPS outlets dotted around the house. The remainder of the gear is in the granny flat, and I have another bigger UPS for that.The old SmartUPS had/have massive surge suppression. Plenty of MOV's and individual & common mode suppression. Huge inductors. <Knock on wood> I've never lost a bit of equipment plugged into the UPS. I've lost stuff just plugged into the wall however.Every couple of years I strip 'em down, re-calibrate them and replace the MOV's. Cheap insurance. If you buy them new, APC have a significant warranty to cover any equipment that was connected through one of their devices and gets smoked. They put their money where their mouth is.I've looked at surge supressors and fluffy commodity electronic protectors, but I've never seen *anything* like the suppression that goes into a quality UPS.For really expensive stuff, I have an MGE full online (charger/inverter) UPS but it is noisy and I only pull it out for special occasions.Total on UPS's & batteries I've spent less than $1000 over 5 years. My neighbours have lost more than that with surges, brownouts and spikes.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 09:03:28 am
content: Quote from: BradC on March 11, 2015, 08:55:41 amFunny you should mention that. I have line interactive APC SmartUPS on my gear. A big one powering the rack and a small one for my desktop PC and monitor.Was thinking about replacing it with an online UPS as the batteries are about due to be replaced. The online models have really come down in price.I'm with you though. So far so good!

author: SteveyG
author_rank: Unknown
timestamp: March 11, 2015, 09:14:30 am
content: I disconnect everything if there's a storm.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 09:17:32 am
content: Quote from: SteveyG on March 11, 2015, 09:14:30 amThe trouble with that is, what if you aren't home? Certainly in Australia (at least in the eastern states) storms tend to develop mid-to-late afternoon, right about the time when you might be finishing work or on your way home.

author: GreyWoolfe
author_rank: Unknown
timestamp: March 11, 2015, 01:18:21 pm
content: I have 3 APC SmartUPS 1500's in the office, 1 for company laptop and networking gear, 1 for personal computer and ham radio gear and 1 for the workbench with the test computer and all the other toys. The main TV and cable box has one also. I have lost stuff plugged into the mains but nothing plugged into the UPS. I also like the AVR function. These were all decommissioned company assets and since I am using 2 of them for company purposes, they still pay for the batteries.

author: LabSpokane
author_rank: Super Contributor
timestamp: March 11, 2015, 03:25:41 pm
content: Step one is to install lightning rods on the structure with an appropriate grounding system. There is no device that I'm aware of that will shunt a direct strike away from your equipment. All one can really protect against is induced currents from nearby strikes.Then make sure you have a solid ground system in place. That may mean installing more ground rods near your existing rod at your meter and bonding them all together. I would strongly advise having more than one rod and bonding them together if you see many storms. What you should NOT do is distribute ground rods around the structure and try to ground locally thinking that will be better. You want the system to see a single earth ground. Distributed grounds will cause you nothing but grief due to ground loops.After that, it's incremental protection. If I was in a lightning prone area, I'd have a suppressor on my main panel as well as suppressors locally on my equipment. Just keep in mind that all protective gear is utterly useless without a solid earth ground at your meter.

author: SeanB
author_rank: Super Contributor
timestamp: March 11, 2015, 04:37:18 pm
content: With your equipment you need to have a SINGLE connection of all incoming cables with a large copper wire ( or better a broad copper strap) to a good local ground rod or better a ground mat, with low resistance. The single point has incoming mains, incoming phone, incoming cable and terrestrial and satellite TV all coming to a common copper bar with a good connection to the shields of the cables and a good short connection between the MOV and spark gap units used on the individual lines. Then you have the server rack or your office computers connected only to that point.This does help, though for a direct strike all bets are off. You will also need a incoming distribution board lightning arrestor at the service input, and another at the distribution board, both to a local ground mesh, which can, if they are within a 3m range of each other, be bonded together or even be the same one. Preferably have the phone and cable come in at the same point with the shield of the cable or the common mode spark gaps connected to this as a first line of defence.I lived in a small town, where one fine day there was a storm 40km away in the mountains. Lightning struck the overhead lines leading out to serve all the farms, and, aside from blowing sections of the 40km of wiring to vapour, it went into the digital exchange, even through the incoming telecom grade surge arrestor cascade. Blew up every electronic part inside the exchange, and the arcing inside the card cages welded them to the racks as well. The only thing that survived was the 48V local battery, a 250Ah lead acid wet cell bank. The exchange had to be cut apart with grinders to get it out, and it took 3 weeks for the phones to work again.

author: German_EE
author_rank: Super Contributor
timestamp: March 11, 2015, 05:05:25 pm
content: Do you really need your "pride and joy" in the middle of a thunderstorm? No? Then unplug everything including the network cables and isolate the rack from the outside world. NOTHING will protect you from a direct lightning strike so just make sure that your backups are tested and you will be fine.Count yourself amongst the lucky few that your power supply did not kill your motherboard and hard drives when it died. Many of them put a high voltage on the 5V and 12V lines during their death throes.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 05:39:16 pm
content: Quote from: German_EE on March 11, 2015, 05:05:25 pmMy entire rack is isolated from the outside world as much as possible. The only thing that isn't is the ADSL line (which hopefully soon will be fibre). We don't have overhead power lines here so the chance of a direct strike into any equipment is negligible.Thank goodness for Supermicro gear hey? Didn't miss a beat.

author: LabSpokane
author_rank: Super Contributor
timestamp: March 11, 2015, 05:56:57 pm
content: You still can have trouble from induced currents from ground strikes. Buried electrical cables are not all that deep.

author: Trey
author_rank: Contributor
timestamp: March 11, 2015, 06:05:07 pm
content: You might want to look over articles on the ARRL site. They are ham radio related, but a lot of the same concepts apply.http://www.arrl.org/lightning-protection

author: jahonen
author_rank: Super Contributor
timestamp: March 11, 2015, 06:36:13 pm
content: The best place for surge protection against lightning induced currents is in the main distribution panel. Something like Phoenix Contact FLT-CP-3C. This is the first thing you'll want and it gets the most surges. That is the first level protection. In addition, you could use UPS or something near the device to be protected. UPS is not a substitute for proper system level SPD.Having a surge protector in main distribution panel ensures that there will be no large voltage differences between ground points in electrical system. Telecommunication lines must also be surge protected to the same point to ensure that they won't drift apart from electrical ground and destroy modems. Phone line copper may vaporize if the surge protection is hefty, thoughThat is pretty much everything one can do, there is no way one can prevent the earth ground potential from rising due to lightning currents as earth is relatively poor conductor at multi-kA level. But it doesn't matter if everything rises equally and no high voltages are present between different cabling systems.Regards,Janne

author: mtdoc
author_rank: Super Contributor
timestamp: March 11, 2015, 09:25:33 pm
content: These Midnite Solar SPDsare marketed primarily for off grid PV systems but can also be installed on any Mains service panel.They are well designed and tested:

author: madires
author_rank: Super Contributor
timestamp: March 11, 2015, 09:48:51 pm
content: Quote from: Halon on March 11, 2015, 08:24:00 amActually it's common pratice for redundant PSUs to connect one to the UPS and the other one to mains when you got just a single UPS. If the UPS fails or needs to be switched off for maintenance the server will still have power via mains. You could buy a second UPS or a power strip with a proper overvoltage/surge protection. APC, for example, offers those too. Another idea is to install an overvoltage/surge protection in the mains panel for the whole house, as already stated.

author: GreyWoolfe
author_rank: Unknown
timestamp: March 11, 2015, 10:31:28 pm
content: Quote from: Halon on March 11, 2015, 05:39:16 pmNothing is above ground here. A strike on the street in front of the house took out 2 computers plugged into the mains, the cable DVR and the MTA. 2 ports on the router were damaged-the ones the computers were plugged into and a 2 Meter antenna and 70 ft of coax were rendered dead. At least there was no radio connected to the coax and the 2 computers were old freebies no doing too much. The cable company took a day and a half to get here because that storm caused widespread damage. It happened on a Sunday evening and the repair tech showed up mid morning on Tuesday.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 10:54:47 pm
content: Quote from: madires on March 11, 2015, 09:48:51 pmNow that you mention it, I think that's why I had one PSU connected to mains. I had issues with a UPS a while ago so while I stuffed around with that, I just swapped one of the leads to keep it running.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 11:19:19 pm
content: Quote from: jahonen on March 11, 2015, 06:36:13 pmA few of you have mentioned this and I think this is a great idea. I'm in the process of building a new house at the moment so I'll have a chat to the electrician and get something installed. I'll be moving to an area with overhead lines which increases the risk.I'd imagine this devices would require replacement periodically even if they are still providing power to the home? Would it be the case where each surge will reduce their serviceable life?

author: LabSpokane
author_rank: Super Contributor
timestamp: March 11, 2015, 11:29:41 pm
content: Any device with MOVs has a finite lifespan. Unfortunately that life is totally dependent on the electrical environment it's in. Most have an indicator for when the device has reached service life.Installing the device is simple and will add virtually no cost to your home.

author: cosmicray
author_rank: Frequent Contributor
timestamp: March 11, 2015, 11:46:10 pm
content: Quote from: GreyWoolfe on March 11, 2015, 10:31:28 pmI have witnessed a fascinating amount of lightning induced voltage surges in underground buried wires. The common theme seems to be that underground wires act as a lightningantenna, and will conduct some about of the strike to one end or the other. Proper shielding/grounding may help, but I'm very wary of what those 200m runs of wire can pick up.

author: Unknown
author_rank: Unknown
timestamp: March 12, 2015, 01:53:59 am
content: I pulled apart the blown PSU. Can't seen any burn marks or smell any magic smoke. The LED still stays orange indicating a fault condition. Maybe the MOVs did what they were supposed to do? There are three I can immediately see on the board itself plus another two directly on the back of the IEC input connector.In any case, I've ordered two more; one replacement and a spare. Should be arriving today.(Those big ass caps look menacing.)

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 12, 2015, 04:18:56 am
content: Add some motor run caps so the MOVs won't be degraded by common, low energy surges.