I have an old (1960s) apartment with 2 prong ungrounded outlets.
A) If I open the outlets and there is no grounding wire, and then add a
GFCI outlet, this will protect me from electrical shocks, but won't
protect my computer from surges.
So: could I add a whole house surge protector at the service box? The
service box uses fuses.
B) If I open the outlets and there is no grounding wire, how difficult
would it to wire grounding wire from the outlet to the service box?
Does an electrician have to do it? Any special gauged wire or
precautiions necessary? Do I have to wire it inside walls?
C) If I add a GFCI breaker to the service box, will this function as a
properly "grounded" GFCI and allow any computers on the circuit to be
protected by surge protector strips?
The first thing you should do is verify that there is no ground. If the
cable is metal, that would serve as ground and you can buy ground wires to
connect to the box and receptacle or self grounding outlets
exactly, upgrading to 3 prong is easy if metal cable like BX or conduit
was run in the first place.
you might also ask your neighbors, who have likely been thru this.
to protect computer a UPS is prefered, be sure to run phone and modem
A word of caution. If the cable is actually "BX", which is the cable
first manufactured at General Electric's Bronx plant, then the jacket
will not serve as an effective Equipment Grounding Conductor. Since
"BX" cable has an unbonded spiral metal tape jacket it does not provide
a low impedance pathway for fault current to return to it's source. The
resistance of the unbonded spiral metal tape jacket can be very high
which would allow a fault to continue without opening the circuits Over
Current Protective Device (OCPD). The installation of a GFCI at the
panel supplying the circuit can mitigate that condition because the
jacket will probably be able to carry the six milliamperes that it takes
to trip a GFCI.
The installation of a Transient Voltage Surge Suppressor at the source
of the circuit is the best way to protect such a circuit against spikes
and surges. Make sure that the TVSS you install provides single point
protection to the power and any other wired utility that is connected to
the equipment your trying to protect. In order to keep the TVSS from
taking a continuous beating and failing prematurely you will need to
insure that the grounding electrodes for the power, telephone, cable,
and any antennas are effectively bonded together in order to serve as a
single grounding electrode system. Having the different grounding
electrodes behave as a single system is far more important than the
actual impedance to ground of the grounding electrode system.
Well we aren\'t no thin blue heroes and yet we aren\'t no blackguards to.
That's a good suggestion.
Ground propagated via conduit and junction boxes may not be very good ground
(higher resistance than a ground wire). I'd add an additional test to verify
Connect a hair dryer between hot and the proposed ground (the metal box in
this case). If it works, then you have a good ground. If the hair dryer is
weaker than normal, then you have a weak ground.
There is a small chance someone cheated and the junction box is actually
connected to the neutral wire. Other than visual inspection, I cannot think
of a good way to detect this.
Regardless of whether you have ground or not, a GFCI will protect you from
accidental electrocution. A GFCI breaker in the panel will not generate a
ground at the receptacle, therefore it does not offer any surge protection
benefit. On the other hand, a surge protector at the panel will offer
You can run a separate ground wire to all the receptacles and upgrade them
to 3-prongs. The ground wire should match the hot/neutral wires in size. You
can route it anyway you want.
the BEST protectin for a computer is a UPS, it preevents system crashes
during brownouts and short interruptions, while allowing a ordely
system shutdown thru software if the outage lasts long.
surge protection doesnt preevent system crashes thus it doesnt help the
most common computer trouble corrupteds data being written at the time
of a outage.........
Sorry but your wrong, Most quality UPS TODAY include 10 grand worth of
replacement coverage if a connected device is damaged by a surge. I
have a APC on my satellite DVR and know friends who lightning took out
their satellite receiver:(
APC replaced them with no hassle:)
I was not talking about a particular brand of UPS. Nor was I talking
about combination UPS TVSS devices. Ive worked in power production and
quality my entire adult life and I know from experience that my
statement is true. A switching UPS, in and of itself, does not provide
surge and spike protection. A continuous duty UPS provides inherent
surge and spike protection by always having the battery between the load
and the public power.
"This alternating current stuff is just a fad. It is much too dangerous
A protector needs a ground is because ground wire must be short to
earth. Not just safety ground back to the breaker panel. Earth
ground. An effective protector shunts lightning 'less than 10 feet' to
earth. Ineffective protectors hope you never learn what a shunt mode
protector does - earth the transient. Earthing - not safety ground -
determines protector's effectiveness.
A 'whole house' type protector is a best solution because it makes
that essential 'less than 10 foot' connection to earth. Earthing so
essential that breaker box earthing must meet and exceed post 1990
National Electrical Code earthing requirements. You probably need
Again, how earthing (not just safety ground) is connected makes a
protector effective. That connection from each AC electric wire,
through the protector, and then to an earthing electrode should be as
short as possible with no sharp bends, no splices, not inside metallic
conduit, and separated from all other non-earthing wires. Earthing
wire is carrying a potentially destructive transient. If bundled with
other wires, then it may induce transients on those other wires. Just
another reason why ground wire inside a BX cable is safety ground, but
not sufficient for earthing.
That 'whole house' protector will protect computer AND everything
else in the house for about $1 per protected appliance. 'Whole house'
protector is superior protection for both two prong and three prong
The best information I have seen on surge protection is at
- w_tom provided the link to this guide
- 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"
- it was 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"
- it is published by the National Institute of Standards and Technology,
the US government agency formerly called the National Bureau of Standards
- it was published in 2001
Both guides were intended for wide distribution to the general public to
explain surges and how to protect against them. The IEEE guide was
targeted at people who have some (not much) technical background.
Both say plug-in surge suppressors, which w_ refers to as "ineffective
protectors", are effective.
The primary action of a plug-in surge suppressor, as is clear in the
IEEE guide, is clamping - not shunt mode, series mode, or earthing.
Since that viloates w_'s religous principle that "earthing ...
determines protector's effectiveness" w_ apparently can't read and
understand these guides.
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