Protecting Switches from Power Surges

[JeffGatti]

Hi Folks,

I have a client that just blew out a bunch of ports on 3 switches on their rack.

My technicians are going to replace them, and recommended getting these APC rack mounted ethernet modular surge protectors.

Have any of you ever dealt with this problem before? The reason I am posting is NOT because I don't trust my technicians, but because this client has had this problem before. Please look at my senario and give me the courtesy of your expert opinion to try and prevent this costly problem from occuring in the future.

The main building (that recieved the bulk of the damage from the lightening strike) has:
2 - 48 port GBIC Switches (fiber)
1 - 24 port GBIC Switch (fiber)

5 campus buildings are connected to this main building multimode by fiber.

There is a 6th building that has CAT5 run to the main rack (I have been on them about running a fiber line, but as most educational facilities go, it takes disasters to make them move most of the time)

What do you think is the best way I can protect these switches from blowing out in the future?

Your advice is appreciated.

Jeff

 

[KiscoKid]

Jeff

I think it's safe to say most experienced networking professionals have had to deal with this scenario before albeit you're quite unlucky to have the same equipment hit twice. I do however offer the following for your consideration.

Firstly consider the potential sources of power surges. These can occur from outside wiring, aerial lines, unshielded cables, long cable runs, telephone lines and power lines.

There are a few ways to protect your equipment from power surges through their inline power supply. Which approach you take will inevitably be decided on cost and the impact to your business by losing these network devices and thus the users/servers connected to them. Typically people employ the following schemes:

1. Surge protection/supression/power conditioners. The APC units you mentioned fall into this category. You could do worse than purchase a surge protector that has a warranty that not only covers the unit self, but the devices that it is protecting. Typically this is the least cost implementation.

2. Uninterrupted Power Supply (UPS). A good UPS will do everything the APC unit does but, in addition, it will ensure the availability of your equipment during total loss of power. I've heard of UPS's that can actually gracefully shut down servers etc if it detects loss of power. UPS's can range from quite a couple of hundred (for backing up a single device or two) up to a few thousand (for backing up an entire server room)

However as I mentioned before, protecting your power supply only is no guarantee another lightning strike won't take out your equipment again. Unfortunately there is no easy way to rectify this situation. Only after careful investigation to identify all sensitive components and all possible paths for lightning currents and voltages, followed by the design, specification, installation and maintenance of a protection system may truly protect your infrastructure.

However, that said, consider some of the following pointers -

1. External fibre cable itself doesn't conduct electricity however they are often made with a conductive metal sheath which could result in damage to the cable itself from a lightning strike.

2. Shielded cabling reduces power surges by providing a preferred path for lightning surges rather than the actual circuit itself. To be completely effective though ensure each end of the cable is properly grounded.

3. For any cable that connects over long distances (leased lines etc), strongly consider installing surge suppressors as near to the devices as possible. I know Cisco sell surge supressor DTE/DCE cables for serial connections.

As I've stated, there is no hard and fast answer regarding protecting your infrastructure but hopefully this has given you some food for thought.

I hope this helps.

 

[Jsteve]

KiscoJid said it well. I would also add the you consider grounding your cabinets.

 

[jneiberger]

I would avoid APC unless their stuff has improved recently. Their charging circuitry isn't designed very well, which causes low battery life and swelling of the battery. I can't count the number of times that we had to throw and entire UPS away because we couldn't get the battery out safely.

And, when they do fail, the power outlets fail so you lose power to your protected equipment. I'd prefer that it failover to building power if the battery dies so your site stays up.

We've switched to Powerware. Better protection, better charging circuitry, longer battery life, failover to building power, cleaner power while on backup, etc. We use the 9125 models.