We recently had a storm in my area. Once the storm passed, many telephones and analog telephone lines stopped working. We soon discovered 3 analog cards in the switch failed, and around 15 analog telephones failed also.
We had the analog cards and telephones replaced, in addition we had a telephone personnel come out and he said that the switch has protection because its on UPS' and there is some fuse boxes which are supposed to absorb an surges.
Is it possible that the surge came from inside the building? Say from those telephones that died? The telephones have a data port where people can plug in their laptops and use their dialup accounts. Would it be worthwhile purchasing some surge preotection for all of our analog telephone sets?
The storm most likely caused the surge of power. Don't forget it could have got into your phone system from the power lines *and/or* the phone lines. Lightening just loves metallic conductors and is not at all fussy which.
Your fuse boxes almost certainly have surge protectors which will stop comparatively minor surges. However it can be very difficult (read expensive) to prevent almost direct lightening strikes.
The likes of Krone have surge protection modules, but you have to weigh up the cost benefits, a lot would depend on just how lightening prone your area is. Your recent incident has probably been quite expensive, but if its a 20 year event, then its probably cheaper to wear it.
The cheapest solution of all is too unplug sensitive equipment during a severe storm. OK, you have business downtime for a short time, but everything can be got going again very quickly & cheaply compared to your recent experience.
Do not confuse surge protectors with surge protection. They are two different components of a surge protection 'system'. To have damage, a surge must first form a complete electrical path incoming and outgoing through damaged electronics. First the transient flows through everything in that path. Then much later, something in that path fails.
Are your telco 'whole house' protectors, installed for free, connected 'less than 10 feet to the building's single point earthing electrode? If not, then lightning has one possible incoming path to find earth, destructively, via electronics. However telephone lines are not the most likely source of incoming transients. First, because those free 'whole house' protectors are probably earthed. Second because telephone lines are protected by higher utility wires that are source of most electronics damage - AC electric.
Is that UPS connected by a 'less than 10 foot' dedicated earthing wire? Probably not. Therefore UPS quietly forgets to mention it does not protect from the type of transient that would cause your damage. No earth ground means no effective protection. So they don't even claim protection from each type transient in their numerical specs. They instead hope that others will promote that UPS as protection using myths.
First we define the incoming and outgoing electrical path. Both must exist to have damage. First the transient finds a path to earth incoming on AC electric, and outgoing to earth via telco provided 'whole house' protectors. Long after a transient is flowing through everything, only then, does only something in that path fail. Most often damaged are components on phone line side of electronics. This because a human permitted a direct lightning strike to enter the building on AC electric.
Do you really think that silly little component inside a UPS will absorb what three miles of sky could not? Another myth promoted by those who never learned basic protection concepts - especially the most critical component in every surge protection 'system' - single point earth ground. No protector protects by stopping, blocking, or absorbing. No earth ground means no effective protection. And yet it is routine - even before WWII - to suffer direct strikes without damage. The technique is same as Franklin demonstrated in 1752. They are called shunt mode protectors. They shunt (divert, connect, clamp, redirect) a transient to earth on a path that is not destructive - as Franklin did in 1752.
Your telco has a $multi-million computer connected to overhead wires everywhere in town. Do they disconnect for thunderstorms? Do they routinely suffer damage? Of course not. They don't make foolish claims that a UPS without dedicated earthing is somehow protection. Nobody stops or absorbs such surges. Telco earths every incoming wire where 'whole house' 'protectors perform best: up to 50 meters away from the computer AND very short distance to earth. Therefore protection found inside all electronics is not overwhelmed. Direct lightning strikes occur often and without any damage. An effective protector is nothing more than a connection to protection - earthing. Where is the dedicated wire, 'less than 10 foot', from that UPS? Does not exist. Therefore is not effective protection.
Sound like you have suffered a classic example of damage. Incoming on AC electric. Outgoing to earth on telephone lines. Those devices that made the better connections to earth would be damaged.
You have two tasks. First inspect the building's single point earthing. It must meet and exceed post 1990 NEC requirements so that all incoming utilities can connect 'less than 10 feet' to that electrode. Second, every incoming utility must connect to that earthing before entering the building. Connected either by hardwire (coax cable) or via a 'whole house' protector (AC electric and telephone).
Manufacturers of serious AC electric protectors also have names that every electrical contractor knows as responsible: Square D, Siemens, Cutler-Hammer, Leviton, Intermatic, and GE. These 'whole house' protectors are sold in Lowes, Home Depot, and electrical supply houses. They have that all so essential 'dedicated earthing wire' that is missing from ineffective and overhyped type protectors. (Again where is a dedicated earthing wire from the UPS?)
Above is a discussion about secondary protection. Each layer of protection is defined by the one and most essential 'system' component
- earth ground. Primary protection system must also be inspected:
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Notice what ineffective protector manufacturers do not provide and refuse to discuss. 1) No dedicated earthing wire. 2) No earthing discussion. Protection from direct lightning strikes, without damage, is routine. But it means you first learn how protection is achieved. Essential is a path, via single point earthing, so that the transient does not enter the building, does not find destructive paths to earth via electronics, and does not overwhelm protection already inside all electronics. Your investigation starts by learning if your earthing even meets post 1990 National Electrical Code requirements. Protectors are only as effective as their earth ground. It is routine to suffer direct lightning strikes (a lightning strike to AC wires down the street is a direct strike to your electronics), and not suffer damage.
The effective soluti> We recently had a storm in my area. Once the storm passed, many
The reason I asked about an ariel cable running to sets is, that I had a customer with that setup. They had regular telco type protectors at each end of the cable. Had to order protectors that were current rated for around 20 something milliamps instead of the ones that were installed, 300 ma I think they were rated at. The last time I heard about this customer, the new protectors did help quite a bit. Have to ask in the office tomorrow about them.
w-tom brings up some good points on grounding. I will add one more thing.
Lightning has to be one of the most commonly misunderstood phenomina on our planet, people assume that in order to suffer damage they need to be struck by or in the path of a lightning bolt. This is a false assumption.
When a bolt of lightning strikes either, cloud to cloud or cloud to ground, everything in the area of the discharge has a higher potential of voltage than it did just prior to the strike. Higher near the epicenter decreasing exponentially as you get farther away. (see inverse square law) This potential is looking for a path.
There are many strange repercussions from a lightning strike, think about what it actually is. Many millions of volts have jumped a gap of miles. The flowing electrons have ionized the air causing the resistance to drop to zero and the current flow to go infinite.
What type of electro magnetic field do you think is generated by that amount of electron flow?
Any turn of wire, or conduit not grounded could instantly become a transformer secondary output coil looking for a closed path.
I had this forcibly taught to me one summer at an air show. Just as we were leaving and running for our cars a large thunderstorm came up. At the moment I reached for the door handle on my car a bolt of lightning streaked across the sky from cloud to cloud. My car sitting on rubber tires was not grounded, I was. It felt like about 300volts streaming thru my skin on my arm and down my leg.
When you look at modern solid state electronics, It only takes about 25v over rated voltage to cause damage. The only way to offer some type of protection is to make sure that nothing is left un-grounded.
Oneac makes a full line of protection devices, everyone with a dedicated ground point on it.
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