Are the building wiring fault indicators ever known to be problematic?

[Anonymous user]

I just purchased a new Back-UPS XS 900 to replace an ES 350 that served me well for over 3 years. The 350 was admittedly WAY too marginal and would have only given me around 3 mins. with the high powered dual CPU (not just dual core, dual CPU) full tower computer that runs 2 video displays. I have it set with a single desktop window, spanned across 2 monitors. Initially, the monitors were 17" CRT's. At that point, I likely wouldn't have even gotten 3 min. but what I did was to only plug the left side monitor (with the windows "Start" button) to try for a graceful shutdown, and the right side monitor plugged into just surge protect to try and maximize runtime on battery, while still permitting access to shutting down. I suppose I couldn't have been too "graceful" with only 3- mins.

Changing to (2) 19" LCD monitors was better. Still only had the left on battery back-up. This probably upped time to maybe 6 or 7 mins.

Anyway, battery in the ES 350 finally bit-the-dust, and when I saw a great deal on the XS 900, I decided to jump at it rather than put money into a new battery.

Now I'll probably have AT LEAST 30 mins. even with both LCD's on battery, maybe more. Definitely more if I leave it with only the left monitor on battery. Certainly, this will be a lot closer to what a reasonable back-up period SHOULD be.

But I've got a strange situation. The ES 350 did not have a building wiring fault indicator, so I never noticed anything. This new XS 900 does; and despite the fact that my house wiring has NEVER seemed to have ANY problem, no matter which outlet I try it in, the XS 900's wiring fault indicator is on constantly. There is no other trouble. Unit post's up just fine, leaving only solid green on light.

I even have a number of outlets that are GFI protected. The GFI's are fine. Yet even when plugged into a GFI, the fault indicator lights up.

Obviously I can continue to check things out. My house wiring, try it out in another house, etc. But before I get crazy, is it possible that the fault indicator circuit is the actual problem? Are these known to be problematic?

Part of the "great deal" on this unit I spoke of was a $15.00 rebate, so before I start cutting UPC symbols out of the box, I'm trying to cover all the angles on whether I should exchange this unit for a another.

[Anonymous user]

No GFI will indicate an open ground wire for exemple. The GFI is constantly measuring what comes in and what comes out, I mean, if 10Amps are coming in, 10amps should be coming out via neutral wire - the neutral wire is the functional ground, not the safety ground, so when there is a fault that causes x amps in / x amps out to get unbalanced, the GFI makes the circuit breaker trip. This happens when someone accidentally touch the phase (hot) wire or when there is a current leakage because of numerous reasons, it can be a demaged wire touching something that grounds it or because of an internal applience fault making current being dumped to the the safety ground wire, this is considered to be a fault, a safety fault, so the circuit breaker should trip on this conditions. The GFI helps the circuit breaker trip a lot faster and at a minimum leakage current.

The building wiring fault LED might be indicating three things that you wouldn't notice otherwise. It indicates reverse polarity. Almost any applience if not all, can work with the polarities reversed, but this make the protection devices not work properly because the circuit breaker or fuse inside the device will be "protecting" the neutral wire instead of the hot. There are other issues regarding reversed polarities that I can't remember now, but the other thing this indicator might be telling is an open ground. Your outlet may not have a ground wire or its demaged. The third and last thing the indicator shows you is overloaded neutral wire, but this is not very likely within a house. If you correct the ground wire and the polarities and the wiring fault LED is still on, try unpplugging everthing inside your house. If the LED is still on, your UPS might have some kind of problem.

Either way, you should have an electrician check the electrical installation inside your house. Ask him to check the safety ground wire of every outlet and check for reversed polarities.

[BillP]

to elborate on what rau said,

a site/building wiring fault indicates:

-missing or loose ground
-reversed polarities
-overloaded neutral wire

i am not too experienced with GFIs or anything but ive never heard of that causing a site wiring fault.

[Anonymous user]

GFIs are devices made to basically protect lives and not to notify one about faults on the safety ground wire in the outlets as some might believe.

100% of the current (amps) consumed by the appliances has to return to the neutral wire, if this ain't happening, it's because the current is going somewhere else than the neutral wire and it basically happens when:

- Someone is getting electrocuted - one becomes the "neutral wire" by closing (grounding) the circuit through its body.
- When the isolation of a wire is bad and the wiring touches a metalic part, which is capable of sending current to ground.
- Electronics, especially computers have a little bit of leakage current to the safety ground, usually not enough to make the most sensitive GFI break the circuit, but this might happen when many PCs are attached to that specifc circuit. If this happens, one less sensitive GFI can be chosen, but the sensitivity has to be carefully analysed before changing the GFI.

GFIs come in a variety of sensitivities, the most sensible ones are used to protect one from being electrocuted when accidently touches the hot (phase) pin of an electrical appliance cable when plugging or unplugging it. GFIs made to save one from being electrocuted are usually set to 30 miliamps of leakage current. If 30 miliamps is being leaked somehere else than the neutral wire, the circuit is instantaneously turned off by the GFI.

In Brazil we call it a Residual Difference Circuit Breaker or something close to it, (DDR in portuguese or DR for short or an IDR for GFI without a circuit breaker built-in). If there is a difference in the sum of what comes in and what comes out, the GFI breaks the circuit, that's basically it.

Message was edited by: rau

[ginbot86_apc · Accepted solution]

(sorry for the late reply) If you go to a hardware store, you can find an outlet tester to see if there is a wiring fault (live/neutral mixed up, etc.). If it's fine, then the UPS is defective.

[dnchrist]

I had the same issue with a  Back-UPS BX-1500G.  I checked it with a tester and found no problem.   I bought another one and have no problem.  The initial unit is defective.  (Don't believe everything you read in the manual.  It also told me my batteries were bad)

[Teken]

As another data point this can be caused by connecting the UPS to an extension cord / power bar that is missing the ground pin. This problem will sometimes appear when isolation transformers are modified to be used in *Tech Mode*.

Lastly, depending upon the UPS design topology a building wiring fault is caused by a Bootleg Ground. People used this method to fool GFCI testers and the potential home buyer. A more dangerous version is the reversed bootleg ground where the neutral and line is connected backwards to its intended posts.

As of this writing (2024) almost all cUL / ETL certified AFCI, GFCI devices check for proper grounding, wiring (line / neutral) before they will allow you to turn it on / reset. 

NOTE: A wiring fault may also be detected when an outlet is modified to separate the top and bottom outlets. Where the top and bottom are powered by two different breakers. This is especially dangerous if the breakers are on the opposite leg of the single split phase electrical system.