ATOT Electricians, I have a question for you.

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Kaervak

Diamond Member
Jul 18, 2001
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This is a little lengthy, but I need to fully explain the setup for an accurate answer.

Our house was built in the 1950's and doesn't have proper grounded outlets. We've always had three prong outlets, but there's no ground wire. In the back bedroom our CATV drop for the cable modem/bedroom TV comes in. The CATV line is grounded outside to an exterior ground line. On one receptacle there's an APC UPS where the cable modem plugs into and the other receptacle just a regular APC surge protector/powerstrip. For the longest time the site wiring fault lights have been lit on the UPS and PS since there's no ground on the outlet. Recently we got a new TV in the back bedroom which has a three prong grounded power cable. After plugging in the TV the site wiring fault lights on the UPS and PS shutoff. I'm assuming that the TV, connected to the cable box, which in turn is connected to the grounded CATV line, was completing a ground correct? When I either unplugged the TV or disconnected the CATV line from the splitter the site wiring fault lights would turn back on. If there had been an overload of current then everything would have been destroyed since the ground was only complete because of the TV?

I did some searching online and replacing the outlet with a GFCI is the up to code way to correct the ground issue without rewiring everything. So I've replaced the outlet with a GFCI and the site wiring fault lights are back on. Everything is working fine, no weird issues or things refusing to power on. The GFCI itself tests and resets just fine. I'm assuming that with the GFCI outlet in place even with the site wiring fault lights on I'm better off than with the three prong no ground outlet in?

If I had the money available, I'd get the outlet properly grounded and the fuse box replaced with a breaker box too. Anything else I should look out for?
 

Colt45

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Apr 18, 2001
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It's still going to show fault with GFCI, cause there's still no ground... but it should be reasonably safe.
 

ktehmok

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Aug 4, 2001
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It's still going to show fault with GFCI, cause there's still no ground... but it should be reasonably safe.

This. Unless you have the cash to pay for a complete re-wiring of the house, you're about as safe as you can get.
 

Rubycon

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Aug 10, 2005
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It's still going to show fault with GFCI, cause there's still no ground... but it should be reasonably safe.

Except for lightning protection. Don't expect any kind of surge/spike suppression to work properly in the absence of a grounded system.
 

Paperdoc

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Aug 17, 2006
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It's still going to show fault with GFCI, cause there's still no ground... but it should be reasonably safe.

This is correct. A standard Grounded system merely provides a good Ground connection to the chassis of every device plugged into it (with a 3-wire power cord). Then, if ever a wiring fault develops within the device that provides contact from the Hot side of the circuit to the chassis (exposed to human touch), it guarantees that the chassis still stays at near-zero volts for the short time it takes for this abnormal condition to pull a heavy current through the Hot-to-Ground connection to blow the fuse or breaker, cutting off all current supply from the Hot side.

A GFCI device does it differently, and provides NO GROUND. It constantly monitors the currents flowing in the Hot and Neutral sides of the circuit wiring, and they must match if the circuit is working properly. If there is a mis-match exceeding some trigger value (I believe it may be 5 milliamps), the device will cut off the Hot feed (same result as if the fuse had blown) on the assumption that missing current must be going to the wrong place, and that is dangerous. So the two types of devices offer similar levels of protection to people from electrical mishaps, but they are not identical and do it by different mechanisms.

For other purposes, like getting rid of low-voltage stray electrical noise signals, a GFCI device that does NOT provide any true Ground connection is of no use at all.

Unfortunately, the Ground connection you accidentally created through the TV and its cable shield satisfies the UPS's test circuit for the presence of a Ground, but it is NOT heavy enough wiring to provide a reliable route to carry a heavy current without trouble, sufficient to cause the fuse to blow. It MIGHT fail to blow the fuse, or it MIGHT blow the fuse but cause significant damage to itself by running the heavy current through light-gauge wiring (like the cable shield). It might even provide a good enough Ground to do the noise-reduction function.

A combination of the GFCI supplying the UPS (for fault current protection) and Ground through the TV and cable (for low-voltage noise removal) should work OK. I am puzzled, though, why you say this leaves the UPS's lights indicating a missing Ground again.

The ideal but cheap way to resolve this is to re-wire ONLY the one branch circuit for this room. There is NO need to replace the fuse box. I would fully expect that there IS a Ground connection from the fuse box to a true Ground source (maybe your water line entering the house), because all such systems (even before the 1950's) required a connection from fuse box Neutral bus to true Ground, and this also normally connected to the metal outer case of the fuse box so it, too, is Grounded. So simply replacing the cable from the fuse box up to each of the outlet boxes in the circuit with a modern 3-wire (Hot, Neutral and bare Ground) cable will provide a good true Ground connection at those outlets. By the way, it's potentially dangerous (and strongly discouraged) to have 3-wire outlets mounted in circuits supplied with no Ground lead, because it can mislead people (obviously, not OP) into believeing they have safe Ground connections.
 

westom

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Apr 25, 2009
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Except for lightning protection. Don't expect any kind of surge/spike suppression to work properly in the absence of a grounded system.
Plug-in protectors - with or without a safety ground - do not provide effective protection. Even the manufacturer's numeric specs made that obvious.

First, safety ground and earth ground are two completely different grounds. Every incoming utility (cable, telephone, AC electric) must connect to the same earth electrode before entering the building. First, for human safety. That will be discussed first.

Post 1990 code requires earth ground to be located close to the electric box. Even a water pipe ground is not longer sufficient. Most drive a 10 foot ground rod (sold even in Lowes and Home Depot) outside and adjacent to the breaker box.

A breaker box quarter inch solid copper wire must connect as short as possible to this earthing electrode. Therefore electric faults (ie a failure inside the transformer) will not cause electricity to seek earth ground through dangerous paths (ie gas meter).

Also necessary is another solid bare copper wire from breaker box to a point as close as possible where the water pipe enters the house.

Next, cable TV must drop down to connect a ground block ($2 in Lowes, etc) to that earth ground. Cable must be earthed before entering the building. A 12 AWG wire from that ground block to the earth electrode. Another connection that must meet only at the same earthing electrode.

Telephone must also be grounded. This connection point usually inside a NID - a box where telco wires meet your household wires. Again, a 12 AWG wire from the NID to that earthing electrode.

Other safety grounds: a bare solid copper wire from cold water pipe to hot water pipe above the hot water heater. Another solid copper wire connecting both pipes into a water meter. Clamps to make these connections to 3/4 inch copper pipes also sold in Lowes, et al.

No ground wire must connect to water pipes (except those listed above. Pipes are not acceptable as an electrical conductor. Those above safety grounds are so that a voltage does not exist on those pipes.

No third ground wire need be routed to wall receptacles. Whereas that would be better, that is not necessary. However any appliance that has a three prong plug must only connect to a GFCI outlet. Any three wire receptacle that is protected by a GFCI must have a label attaches that reads "No Equipment Ground". Also every bathroom receptacle should have a GFCI - no exceptions.

Above is safety ground. Second are upgrades for surge protection. Those connections from breaker box, cable, and telephone must be as short as possible (ie less than 10 feet). Ground wire must have no sharp bends. No splices. Routed separate from all non-ground wires. Not inside metallic conduit. For example, breaker box ground must not go up over the foundation and down to that ground rod. Surge protection means that wire must go through the foundation and down. Eliminate sharp bends. Shorter, Separated from other wires above the breaker box. These additional requirements for surge protection.

The telephone NID box already contains a 'whole house' protector. Like all protectors, it will only be as effective as the connection and earth ground you have provided. Cable needs no protector. That wire (also no sharp bends, etc) from ground block to earth is the best surge protection your cable will ever have. These grounds are typically installed by the utility if your ground existed when they installed their wires.

Other AC electric wires must connect to earth. But if connected directly, then AC electric will not work. So install one 'whole house' protector to connect all other AC electric wires through that solid bare copper wire to earth. One example is a Cutler-Hammer protector selling in Lowes for less than $50.

Above means every incoming wire is at same potential; human safety implemented. Those additional requirements also mean surges need not enter the building - hunt for earth destructively via appliances. GFCI is how the code permits three wire receptacles (for human safety) without running new wires inside the wall.

Appreciate the two different problems. Human safety and transistor safety. Above is minimal for homes with two wire receptacles.
 

IEC

Elite Member
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Jun 10, 2004
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You can install TVSS units on incoming mains/data lines.
 

Kaervak

Diamond Member
Jul 18, 2001
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Bit of an update. I purchased a GFCI outlet tester and like I expected the GFCI outlet shows an open ground. However, testing one of the two prong outlets in the kitchen shows the outlet as properly grounded. I'm guessing that the two prong outlet is grounded by the outlet box itself. Looking around online I came across this: http://www.thisoldhouse.com/toh/article/0,,20065922,00.html Testing the outlet in the kitchen with a circuit tester does indeed light it up indicating it's grounded. On the GFCI outlet, would adding in the grounding wire to the outlet box be an acceptable solution? I doubt the This Old House guys have it wrong, but it doesn't hurt to get a second opinion.
 

Red Squirrel

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May 24, 2003
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I would strongly suggest looking at rewiring with grounded wire, maybe 12/2 (20amp max) or 14/2 (15 amp max), If the basement is not finished you can fish the wires up to all the sockets. You can skip the light fixtures as those would be much harder and they don't really use ground (in most cases) but at least get all the receptacles. If the light fixtures are easy then do those too. Depending on how the house is built and how it's wired this can be an easy job, or a very hard one.

Personally if I was doing this I'd go with 12 awg across the board. This will give you the option of turning any circuit into a 20 amp in the occasion that it is needed.

Though if some stuff is showing as grounded, I'm thinking there might already be a ground wire and maybe they are tied in some spots and not in others. the TV might be acting as a ground as well. If you are lucky this is the case and all you have to do is go around and make sure the grounds are properly connected, and also connected at the panel. I can't see why previous people would have changed a 2 prong to a 3 prong and never attached the ground if it's there though.
 

westom

Senior member
Apr 25, 2009
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Bit of an update. I purchased a GFCI outlet tester and like I expected the GFCI outlet shows an open ground. However, testing one of the two prong outlets in the kitchen shows the outlet as properly grounded.
Appreciate what that tester says. It can never say safety ground is good. It can only report some safety ground defects.

There is no replacement for safety ground inspections. That is what the GFCI does. Provide human safety when no (or inferior) safety ground exists. GFCI cannot provide the other functions also provided by a safety ground.

Sometimes, another appliance on the same circuit can be reported (erroneously) by that tester as a good safety ground. Just another example of a tester not able to report a good ground. That tester can only identify some types of defects.

BTW, wall receptacles on a twenty amp circuit means each receptacle only provides 15 amps max. Means the maximum any appliance may consume is 1440 watts. A receptacle for twenty amp appliances is different. The typical twenty amp circuit to multiple receptacles means only 15 amps - which is well above what most any appliance requires.
 
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