We are in the process of engineering the wiring for the a building and
need to know if we should put special surge or lightning protection on
the circuits that will be running the computers or the standard
protection for the building is adequate.
Approximately 5-8 computers will be running at this location 24/7
it will be in northeastern kansas... lightning can be an issue,
especially during tornado season. The main thing i think is, (this was
handed down to me to research) we want to eliminate using multiple
standalone surge protectors for these PC's and can we just beef up the
wiring systems to withstand anything we could forsee
Here in interior Alaska when we wire the computer buildings for the US
Army Stryker Brigade that uses one hell of lot of computers a UL
certified lightning protection system is installed. We have one
contractor, Star Electric in Fairbanks, Alaska that has the
Surge protectors and surge protection are two completely different
components of a building's protection 'system'. Protectors are nothing
more than a temporary connection to protection. They are shunt mode
devices. Every incoming wire in every cable incoming to a building
(because every wire inside a building must be part of the 'system')
must be earthed where entering. All wires must make a 'less than 10
foot' connection to same earthing electrode.
Principles are defined in this application note and figure from one
Effective surge protector is nothing more than a temporary connection
to earthing. That protector will only be as effective as its earth
ground AND its connection to that earthing. Even that connecting wire
must exceed what is required by post 1990 NEC. For example, no
splices, no sharp bends, not inside metallic conduit, and as short as
practicable to earthing electrode. That means the wire does not go up
over foundation and down to an earthing rod. Instead that wire goes
through foundation and down to earthing rod so that ground wire is feet
Earthing wires must also remain separated from other none earthing
wires. Earthing wires for each utility must remain separate until all
meet at the same earthing electrode.
Further discussion in previous posts:
How transmission lines would not damage the telephone exchange (CO) or
modems in the newsgroup tmnet.communities on 1 Dec 2006 entitled
Because an exchange cannot be damaged by
Same concepts to eliminate lightning damage to inverters for
photovoltaic system in the newsgroup alt.solar.photovoltaic on 29 Nov
2006 entitled Problems during Lightning Storms at and in following
Appreciate that well over 90% of all trees struck
How telephone appliances may have been damaged and how that damage
could have been averted in the newsgroup
rec.games.computer.ultima.dragons on 29 Nov 2006 entitled Thunder
and lightning at:
Reasons for surge protectors are protection from
im.your.c> We are in the process of engineering the wiring for the a building and
The best information I have seen on surges and surge protection is at
the title is "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).
A second guide is
this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency formerly
called the National Bureau of Standards) in 2001
The IEEE guide is better (the NIST guide is less technical).
A service panel surge protector should be used. The guides give
informition on sizing.
Also note the information on single point grounding. The phone and other
incoming non-power wiring should have their protectors near the power
wiring entry and those protectors should connect to the grounding
electrode conductor from the power service close to the power service.
Any significant earthing currents from a surge will cause the "ground"
in the building to rise above 'absolute' earth potential. You want the
grounds for the power system (ground/neutral bond connection) to rise
together with the phone and other incoming systems so there is not a
damaging potential difference between them.
How much additional protection depends on how critical the computers
are. They could, for instance, run from a subpanel with its own surge
protector and have adjacent surge protectors for signal wires to the
computers connected with short wires to the subpanel ground - a local
single point ground.
More information is in the "IEEE Recommended Practice for Powering and
Grounding Electronic Equipment", the IEEE "Emerald" book. If interested
you can get an abstract, the table contents, and chapter 1 - overview at:
When we wire FAA jobs that use a lot of electronics we always install a
surge or lightning protector at the service to their buildings. Also,
lightning protection is installed at the building. In Kansas I would
install both the lightning protection at the service and at the
building. I see a lot of posts on technicl material here, but these
types of protection systems are a matter of fact and have been
engineered many times by existing users. Just call your local FAA shop
electricians - these guys are experts on installing these systems.
Since you don't mention UPS systems, I guess you are planning on
having frequent downtime. Hint: the better grade UPS systems already
have better surge suppression built into them. It all depends on your
building ground system. Read the references that were mentioned in the
I'd not do anything special to the building power system, other then
making sure the ground system is better than the minimums established by
the electrical code. Remember that the electrical code establishes the
minimum safe standards, not best practices. The UPS for each system
will do much better at protecting against more than just surges.