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#1
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2 Prong Ungrounded Outlet & GFCI
I have an old (1960s) apartment with 2 prong ungrounded outlets.
Questions: 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? Thank you. |
#2
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2 Prong Ungrounded Outlet & GFCI
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 "redbrickhat" wrote in message ups.com... I have an old (1960s) apartment with 2 prong ungrounded outlets. Questions: 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? Thank you. |
#3
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2 Prong Ungrounded Outlet & GFCI
RBM (remove this) wrote: 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 thru UPS. |
#4
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2 Prong Ungrounded Outlet & GFCI
"RBM" rbm2(remove wrote in message
... 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 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 the ground: 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 protection. 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. |
#6
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2 Prong Ungrounded Outlet & GFCI
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......... |
#7
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2 Prong Ungrounded Outlet & GFCI
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#8
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2 Prong Ungrounded Outlet & GFCI
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 earthing upgrades. 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 receptacles. redbrickhat wrote: I have an old (1960s) apartment with 2 prong ungrounded outlets. Questions: 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? |
#9
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2 Prong Ungrounded Outlet & GFCI
On 6 Sep 2006 22:45:40 -0700, "redbrickhat"
wrote: I have an old (1960s) apartment with 2 prong ungrounded outlets. Questions: 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? Thank you. A GFCI will function as a GFCI with no ground. It will not create one. -- 109 days until the winter solstice celebration Mark Lloyd http://notstupid.laughingsquid.com "All your western theologies, the whole mythology of them, are based on the concept of God as a senile delinquent." -- Tennessee Williams |
#11
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2 Prong Ungrounded Outlet & GFCI
Thomas D. Horne, FF EMT wrote: wrote: RBM (remove this) wrote: 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 thru UPS. 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. Didn't know that.... I usually see an uninsulated wire sticking out of the BX cable whenever I crack open the box, which is generally tucked into the clamp, I assume that's a ground conductor for a Good Ground. Yes? 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. -- Tom Horne Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you. |
#12
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2 Prong Ungrounded Outlet & GFCI
w_tom wrote: 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 earthing upgrades. 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. Oh. That answers my recent question... 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 receptacles. redbrickhat wrote: I have an old (1960s) apartment with 2 prong ungrounded outlets. Questions: 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? |
#13
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2 Prong Ungrounded Outlet & GFCI
It's a bond wire for a good bond to the cable sheath
"z" wrote in message ups.com... Thomas D. Horne, FF EMT wrote: wrote: RBM (remove this) wrote: 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 thru UPS. 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. Didn't know that.... I usually see an uninsulated wire sticking out of the BX cable whenever I crack open the box, which is generally tucked into the clamp, I assume that's a ground conductor for a Good Ground. Yes? 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. -- Tom Horne Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you. |
#14
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2 Prong Ungrounded Outlet & GFCI
A switching UPS does not protect a computer from transient voltage events. A continuous duty UPS, were the load is always carried by the battery, does provide substantial inherent protection. -- Tom Horne 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 |
#15
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2 Prong Ungrounded Outlet & GFCI
z posted for all of us...
Yeah, if your house was built/wired within reasonably recent times, it will have conduit Conduit? In residential? Not normally. -- Tekkie "There's no such thing as a tool I don't need." |
#16
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2 Prong Ungrounded Outlet & GFCI
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#18
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2 Prong Ungrounded Outlet & GFCI
Tekkie® wrote:
z posted for all of us... Yeah, if your house was built/wired within reasonably recent times, it will have conduit Conduit? In residential? Not normally. In some areas, such as Chicago, it is quite common. -- Tom Horne Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you. |
#19
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2 Prong Ungrounded Outlet & GFCI
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#20
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2 Prong Ungrounded Outlet & GFCI
Thomas D. Horne, FF EMT wrote: You are correct. Modern armored cable is listed as suitable for equipment grounding via the bonded spiral tape jacket. BX on the other hand lacks that bonding strip. Ahhh..... I just mentally lump them all in as BX. Didn't realize there were differences. Thanks. -- Tom Horne Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you. |
#21
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2 Prong Ungrounded Outlet & GFCI
w_tom wrote:
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. The best information I have seen on surge protection is at http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf - 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 http://www.nist.gov/public_affairs/p.../surgesfnl.pdf - 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. bud-- |
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