Re: Whole house phoneline surge protection

letterman@xxxxxxxxxxx wrote:
Every summer I lose at least one modem from lightning (on dialup). I
try to shut off the computer during storms, but then I can not view
the weather radar and watch for alerts. I try to stay online until
the storm gets quite close before shutting down, but I have lost a few
modems from distant strikes. Surge protectors have their limitations,
but anything that helps is worth doing.

However, I have had several answering machines and cordless phones die
too. In rural areas it seems these surges are worse than in a city.
To protect everything, I'd have to install quite a few surge
protectors to handle every phone device in the house. My questions is
whether there is a WHOLE HOUSE surge protection device that I can buy,
and install at the phone block where the line enters the house? That
would be better than numerous surge protectors.


The best information on surges and surge protection I have seen is at:
http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf
- "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is the dominant organization of electrical and electronic engineers in the US).
And also:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001

The IEEE guide is aimed at those with some technical background. The NIST guide is aimed at the unwashed masses.

According to NIST guide, US insurance information indicates equipment most frequently damaged by lightning is
computers with a modem connection
TVs, VCRs and similar equipment (presumably with cable TV connections).
All can be damaged by high voltages between power and signal wires.
Your symptoms sound like high voltage between phone wires and the power system ground. (In that case, shutting a computer off wouldn't help.)

Phone wires should already have an entrance protector that clamps the voltage on the wires to 'ground'. It should have been installed by the phone utility (US and probably Canada). Cordless phones and answering machines are usually powered by 'wall warts'. Wall warts generally are more immune to voltage from phone wires to power/ground wires - might point to a phone entrance protector. I haven't heard of burning one out, but you could ask the phone company to replace it.

It is very important to have a *short* 'ground' wire from the phone entrance protector to the 'ground' at the power service. A short (10' max) wire limits the surge voltage from phone wires to power and ground wires. With a strong surge, currents to earth can lift the voltage of the house 'ground' thousands of volts above 'absolute' ground. To protect equipment connected to both power and signal wires, the power/phone/cable wires must rise together. An example of a 'ground' wire that is too long is in the IEEE guide starting pdf page 40. If the phone entrance protector is too far from the power service you can't have a short enough 'ground' wire. In that case the IEEE says "the only effective way of protecting the equipment is to use a multiport [plug-in] protector" (although you could run a phone wire from the entry protector to the area of the power service, install a 2nd protector, and distribute wiring from there).

If using plug-in suppressors all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor. Plug-in suppressors work primarily by clamping the voltage on all wires (power and signal) to the common ground at the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. Multiport suppressors are described in both guides.

A service panel suppressor may be a good idea. (It won't provide protection from the long 'ground' wire above.)

Check the connection to grounding electrodes as John suggests.

Fuses do not provide protection from surges. A surge is over long before a fuse can blow.

--
bud--
.

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