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Surge protection for DSL and dialup service.

The purpose of this FAQ is to go over the basics of providing a minimal level of surge protection for small business and residential DSL and dialup service.

The devices mentioned in this FAQ are based on personal and field experience of the author and are in no way an endorsement of those devices by Bellsouth. Furthermore, what is presented here is based on experience and not to be considered a recommendation, or an official practice of Bellsouth.

Before proceeding, the first item of consideration is SAFETY.
Prior to doing any work involving a telephone line, it is mandatory that you, the installer, disconnect the Inside Wiring (IW) from the telephone network. This is accomplished by locating and opening the telephone circuit(s) at the Entrance Bridge Network (EBN). The EBN is located either outside the premise inside of the Network Interface Device (NID), or inside the premise, as part of the Inside Network Interface (INI). Unplugging the modular jack on the EBN disconnects the IW from the network. If there are multiple EBNs unplug all of them. Its always better to knock down service than to work unsafely.

Cable TV services may have hazardous voltages present at any time. If you are unsure whether a cable service is safe to work on, get your cable company involved before proceeding with any work involving that service.

Satellite dishes receive their power from the satellite receiver. Before doing any work on the dish or coax, disconnect the receiver from the power outlet and disconnect the telephone cord from the receiver.

Electrical work should only be performed by a competent, properly licensed contractor. If you are going to do the work yourself and are not 100% sure of what you are doing, STOP, and hire an electrician. The life you save may be your own.

Do not do any work involving any of these services when there are storms or lightning in the area. Surges from lightning can travel many miles through a service serving your premise. As such, even a remote strike can result in serious injury or death!

  • A/C Alternating current: The common service provided to the small business and residential market is 240/120 volt 60 cycle alternating current.

  • Bonding: The intentional connection of separate circuits by a conductor. In this FAQ it applies to grounds.

  • Bridging clip: A metallic connector used to electrically connect the terminals on one side of a punch-block to the other side. Wiring a punch-block in this manner and using bridging clips allows the technician to isolate various jacks and devices in the premise to aid in troubleshooting.

  • Brownout: A partial loss of A/C line power. Brownouts can be damaging as they stress power supplies in protected equipment, as those power supplies try to compensate for the loss of input power.

  • Building ground system: A system of ground (earth) connections that are designed to provide the ground(s) for services entering a premise.

  • D/C: Direct current. Telephone lines are powered by 48-52 volts of direct current and 90-130 volts, 20 cycle alternating current to operate the ringer in the sets.

  • Downstream: Any equipment that is installed after or downstream of a surge protector.

  • Ground: The earth. An electrical connection to the earth is known as grounding.

  • Grounded: An intentional or unintentional connection to the earth.

  • Hot: The conductor(s) that provides power to a device from the service or distribution panel.

  • Induction: The inducement of power into conductors by a changing magnetic field crossing that conductor.

  • LAN: Local area network.

  • Listed: An electrical devise is said to be listed when it has been tested by and meets the minimum requirements of a testing/listing organization such as ETL or Underwriters Laboratory (U.L.).

  • Neutral: The ungrounded conductor that provides a return path for the power delivered over the hot conductor.

  • Punch-Block: A terminal block that allows for the quick and easy termination of IW using a tool known as a punch down. The most common types of punch-down blocks are the 66 and 110. In this FAQ the term punch-block will refer to the 66 Category 5 type block.

  • Surge: An increase over and above the normal operating voltage of a circuit lasting more than 3 nanoseconds (3 billionths of a second).

  • Surge protector: A device that monitors the voltage present on a circuit while providing a method to dissipate any excess energy that may become present. A surge protector is said to fire over or breakdown when in the process of passing or dissipating the excess energy.

  • Spike: An instantaneous increase over and above the normal operating voltage of a circuit lasting less than 3 nanoseconds.

  • UPS: An uninterruptible power supply. A device that utilizes mechanical or battery power to provide a continuous source of power.

Surge Protection:
While surges and spikes are two different beasts, they will be referred to in this FAQ as surges except where there is clear need to define them separately.

A surge can appear at any time on any service entering or within a premise. Common causes are electrical loads being switched on or off on the same service or the inductive influence of that load change into nearby conductors. Another cause is lightning, which causes surges by both direct and inductive influence.

A surge damages electronic equipment by exceeding the rated operating voltage of the components within that equipment. Damage from a surge may not appear at the time the surge occurred. This damage may show up at a later time when the component finally fails from the damage. This type of failure is commonly referred to as a Blue Sky failure, as it could happen on a nice day without a storm in sight.

Surge protection takes on many forms, but always involves the following components: Grounding bonding and surge protectors.

Surge protectors monitor the voltage present on a circuit while providing a method to dissipate any excess energy that may become present. Some surge protectors will, in addition to dissipating the excess energy, also isolate downstream equipment to provide an additional level of protection.

Grounding is required to provide the surge protector with a path to dump the excess energy to earth. A proper ground system is a mandatory requirement of surge protection. Without a proper ground, a surge protector has no way to disburse the excess energy and will fail to protect downstream equipment.

Bonding is required to electrically connect together the various grounds of the services entering the premises. Without bonding, a surge may still enter a premise after firing over a surge protector, which will attempt to pass the excess energy to its ground with any additional energy that the services surge protector ground cannot instantly handle, traveling into and through protected equipment, damaging that equipment in the process.

A typical scenario would be: A roof mounted satellite dish receives an inductive surge from a nearby lightning strike. The voltage induced into the dish and its coax fire over the coaxial surge protector, which passes the excess energy to the ground rod connected to the coaxial surge protector. Unfortunately, the earth around this ground rod is incapable of absorbing all of this energy instantly, so some of the excess energy enters the premise seeking additional grounds and in doing so, travels through the satellite receiver and out the power outlet ground. In addition, it will travel through the telephone line to the Telco ground, damaging the satellite receiver.

Now, if all the various service entrance grounds are bonded together there are no additional paths to ground through the premise. Even if all of the grounds cannot instantly absorb the energy, the lack of additional paths to ground through the premise prevents the excess energy from seeking out any additional grounds through that premise and the electronic equipment within. As such, the excess energy remains in the ground system until dissipated, sparing the protected equipment from damage.

Note: Grounding and bonding are not do-it-yourself types of projects. Should you suspect you have a grounding or bonding problem contact a properly licensed electrician or the provider of the service that you suspect is not properly grounded and/or bonded.

Types of Surge protectors:
There are two basic types of surge protectors: Primary and Secondary. Primary protectors are required to be installed where the service enters the premise. These protectors are installed by the Telco, cable TV company or Satellite installer. Local engineering practices determine if the power company will install a primary protector at the power service entrance. Here in Florida, the power company does not install primary protection unless the subscriber requests it and is willing to pay an additional monthly fee for that protection. (Unusual, considering that Florida is the lightning capitol of the United States. [toggle soapbox off].)

Secondary protectors are installed in addition to the primary protectors to provide an additional layer of protection. Secondary protectors will normally have a lower breakdown voltage than the primary protectors they are installed behind. Additionally, many secondary protectors will have fuses to open the circuit downstream toward the protected equipment. Some surge protectors will have circuit breakers instead of fuses. While circuit breakers may be able to protect large motor driven appliances, they are all but useless for the protection of electronic equipment due to the inherent lag time to trip and open the circuit. Basically, by the time a circuit breaker trips, the electronic equipment is toast. The exception to this is in 120/240 volt surge protectors that require circuit breakers ahead of the surge protector to open the feed in the event of a long duration surge and to prevent a catastrophic failure of the surge protector.

Surge protectors come in various voltages which must be matched to the circuit to be protected. A 120/240 volt A/C service entrance surge protector will typically have a hot to hot breakdown voltage of 800 volts and a 500 volt breakdown from hot to ground and neutral to ground. A Telco primary surge protector will typically have a breakdown voltage of 350 volts and a LAN surge protector may breakdown with as little as 15 volts. To work properly without false firing and premature failure, a surge protector will need to have a breakdown voltage of at least 250% of the normal operating voltage of the circuit.

Power line surge protection:
There are many styles of power line surge protectors. The most common of the 120/240 volt A/C protectors are whole house hardwired and plug-in strip protectors.

By far, the whole house hardwired surge protectors provide the best protection. When a whole house primary surge protector is installed at the service entrance, it will provide a solid first line of defense against surges which enter from the power companys service entrance feed. These types of protectors can absorb/pass considerably more energy than any other type of protector, and if one does catastrophically fail, it will not typically be in a living space. Secondary hardwired surge protectors installed at the distribution panel provide a second line of defense for smaller surges and spikes that may not even fire over the primary protector. Branch circuits that feed outlets to PCs, routers, switches/hubs, modems and any other high ticket electronic device in the premise, should be protected by a hardwired secondary protector.

Some sources for hardwired primary and secondary 120/240 volt A/C surge protectors are:



»www.apc.com/products/family/inde ··· b=models

»www.apttvss.com/?src=Overture&OV ··· standard

Generally speaking, the more joules or amps a surge suppressor can handle, the better off you are. Of course as the capacity goes up, so does the price. IMHO, a person is better off buying a primary protector that leaves enough money in the budget to add secondary protectors, rather spending it all on a single primary protector.

Plug in strip protectors are, at best, a compromise. At worst, they may cause more damage than they prevent. While they may do an acceptable job of handling hot to neutral surges, they do a poor job of handling any surge that must be passed to ground. The reason for this is that they rely on the premise wiring for a connection to ground. The premise wiring ground was designed for electrical safety, not to carry surges to earth. If the premise wiring is in steel conduit, that conduit will, in most cases, be the ground. It may be run from outlet to outlet passing through various metal boxes before connecting to the building ground system. If the wiring is non-metallic sheathed cable or Romex, the copper ground wire in the Romex may pass through various boxes where it can be tightly bent and, like conduit, it does not take a direct or straight path to the buildings ground system. All of which make it a poor choice for surge protection. Furthermore, there is no simple way to determine if the premise wiring ground is capable of passing a considerable surge. A ground OK indicator on a surge strip merely indicates the ability to pass enough energy to ground to light the lamp, not that the ground will pass any considerable amount of energy when needed.

An additional problem with strip protectors is that they are normally located at the equipment to be protected, leaving little time for the surge protector to fire over and pass off excess energy before that same energy is present at the equipment being protected.

Then, to add insult to injury, some strip protectors add Telco and/or LAN surge protection within the same device, trying to be an all-in-one sale. Remember bonding? When Telco or LAN protection is added to a strip protector, if the premise ground, which is not designed to handle surges, cannot handle all of the energy, guess where that excess energy seeks out the additional grounds? You got it! The Telco and LAN connections now becomes the path, with disastrous results to those devices.

IMHO, those types of devices are the worst possible choice for surge protection.

Telephone line surge protection:

Primary telephone line surge protection is provided by your telephone company as such this FAQ will not deal with those types of protectors.

Secondary telephone line surge protectors come in three basic styles: hardwire, plug-in and punch-down block mounting. Within those styles are fused and un-fused protectors.

Fused protectors provide an additional level of protection by utilizing fast acting fuses to open the line downstream of the protector, isolating the protected equipment from the energy of the surge. The downside is blown fuses will leave the protected equipment out of service after the surge has cleared, until the fuses/protector have been replaced. Fused protectors are also slighter more costly than their un-fused brethren. IMHO this is a small price to pay for the additional protection provided.

When selecting a fused protector, always use the smallest amperage fuse you can select. Devices that do not pull dial-tone (DSL modems) can use fuses in the sub-amp range while dial-up and line powered devices will require higher amperage fuses usually in the 1 to 5 amp range.

Note: If uninterrupted service is critical you should not a fused protector. Keep in mind, however, if the surge is sufficient enough, the service will still be interrupted due to a damaged modem/router.

Hardwire protectors are similar to the primary protectors installed by the Telco. While they are inexpensive, they pose problems with connection and mounting. To use a hardwired protector, you must have a terminal block to wire the incoming line to the protector. The protector may need to be installed in a listed enclosure to prevent accidental contact with the line. Such a protector could be installed in the subscriber side of the NID if room is available. Many hardwired protectors have internal terminal blocks which greatly simplifies their installation. To install one of these units, all you need to do is run the IW from the NID into and then back out of the protector. The downside of these units is when replacement is required the IW must be re-terminated, getting slightly shorter each time.

Plug-in protectors are by far the simplest type of protector to install. You plug the incoming line into a modular jack on the protector and the line exits via another modular jack. Replacing the protector is easy and quick.

Punch-block protectors are used in professional and prosumer installations where the incoming IW from the NID is connected to a punch-block(s) and then distributed out to the jacks in the premise. These types of protectors take the place of bridging clips, bringing the line into and through the protector and on to the jacks within the premise. If you already have, or are planning to install, a premise wiring scheme using punch-blocks, this is by far the best way to go.

Regardless of the type of protector used, it must be grounded properly. This requires that the protector be connected to the buildings ground system with a minimum of number 12 AWG (preferably number 6 AWG) wire. In order for this to be a good ground, this wire must be run as straightly as possible using the shortest possible run to the buildings ground system. If the ground wire must be bent, do so by using a large radius bend. Avoid kinking the wire and do not run it parallel to or strapped to metallic pipes or other wiring. A good way to accomplish this is to install the protection as close as possible to the NID. This serves two purposes: it keeps the ground wire as short as possible and moves the protection as far as possible from the equipment being protected. Note: if the protected equipment is in another building or a considerable distance from this protector, an additional protector may be required at the protected equipment to prevent an induced surge in the IW from damaging the protected equipment.

Some sources for telephone line and LAN protectors are:




Cable television, satellite and antenna protectors:

The most common surge protectors used with these services are basic spark-gap protectors. These devices permanently ground the shield of the coax and provide a small spark-gap for protection of the center conductor. While not within the scope of this FAQ, they will be touched on due to the fact that they are a service entering the premise and are cross connected with the power service of the premise, and many times, in addition to that, are connected to the premises telephone service. As such, they can have an adverse effect on those services. Another common problem with these services is they are quite often installed with a standalone ground that is not bonded to the buildings ground system and/or installed with a deficient ground. Due to liability problems, cable television companies are getting much better at grounding their services. The same cannot be said for mini-dish satellite installations. Many mini-dish installations are done using aluminum ground wire and minimal ground rods, neither of which is conducive to preventing surges from entering a premise. Should you suspect either of these services are not properly grounded contact the service provider to have the trouble resolved.

A secondary protector can be added between the primary protector and the receiver. This protector will, of course, be required to be grounded in the same manner as a secondary telephone line protector.

Remember, satellite dishs and antennas with top or pole mounted amplifiers will require a DC pass through protector. Antennas without pole or top mounted amplifiers and most cable television installations will not.

An excellent source for coaxial protectors is PolyPhaser.


LAN protectors:

LAN protectors are almost universally the plug-in type. They have eight pin category 5 in and out jacks. The in side would be connected to the equipment most likely to present a surge to the LAN, (the modem/router) and the out side would feed the router/hub/switch. LANs can be quite difficult to protect as they operate at very low signal levels and the components are quite sensitive to surges.

Another problem with LAN protection is that the protection will in most cases be installed adjacent to the equipment being protected. This requires the installation of a good quality surge protection ground at that location. The minimum size of wire I would use for this job would be number 6 AWG. Again, this wire must be run as straight as possible and using the shortest possible run to ground. If the ground wire must be bent, do so using a large radius bend. Avoid kinking the wire and do not run it parallel to or strapped to metallic pipes or other wiring. This ground wire should be dedicated to the LAN and equipment associated with the LAN.

Many professional and prosumer LAN installations utilize rack mounted equipment if your installation is rack mounted, the rack should be bonded to the LAN ground to minimize the chance of current flow between LAN components and the damage that current can do.

Some sources for telephone line and LAN protectors are:




Uninterruptible power supplies:

While not a surge protection device, a UPS goes a long way to protect equipment. Most quality UPSs incorporate internal power line condition devices which, in of themselves, help to block surges and brownouts from damaging downstream equipment. Many UPSs have grounding lugs on them. These ground connections must not be connected to a LAN or surge protection ground. If you are going to utilize one of these connections, it should be connected to the buildings ground system by a separate grounding conductor sized according to the UPS manufacturers recommendations.

Some sources for UPS systems are:




It is not within the scope of this FAQ to recommend a certain surge protection system over another, however, the basics of a surge protection system and order of importance are:

Power service surge protection The most common entry point of a surge into a premise is through the power lines feeding the premise. Remember most power service feeds do not have any surge protectors installed on them what so ever. Your surge protectors are going to be the first and second line of defense against surges entering your premise.

UPS A UPS is a requirement for equipment protection. It will condition the power feeding the equipment and prevent unnecessary interruptions of that power, which can do as much damage as a surge.

Telephone line surge protection While all telephone lines entering a premise are required to have primary surge protection installed by the telephone company, that first line of protection should be backed up by secondary protectors.

LAN Surge protection LAN surge protectors are inexpensive and easy to install. The only drawback is, to work properly, they require a good solid ground wire back to the buildings ground system.

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by Splitpair See Profile edited by KeysCapt See Profile
last modified: 2004-06-13 09:00:04