Site wiring fault light - what if it turns on and off?

[Anonymous user]

Hello, I have an APC ES (can further specify model if needed) on an old building with a monitor, desktop, and 2 small lamps hooked into it. This setup has been installed in the same outlet for about 6 months, and during the summer months when first installed, the site wiring fault light never came on. With colder weather, however, I have noticed on three occasions the following:

- The wire fault light was off, and the computer was running.
- Upon shut-down, I waited over 10 minutes to turn the computer back on, and have noticed that the fault light has come on.
- The second time this happened, the light has gone off by itself after 5-10 minutes of the computer being on.
- I have noticed that the light changes intensity, from a dim red to a bright red, as equipment has been turned on and off.

A few questions follow. If possible, answering all would be great:

- I dismiss a potential reverse polarity because, if so, the light would be on all the time. On another building, I actually experienced an outlet with reverse polarity, and the APC unit (an earlier model) had the site fault light on continuously.
- I suspect that cold weather might be at play. Each time this has happened, the room temperature was in the middle-upper 50s, if not slightly lower. For instance, last Saturday, the light was on during most of the day, and towards the evening, I decided to turn on the heating system. The next day, the light was gone.
- Could the above be a reason for the wiring fault light to come on? If so, what would be the possible reason why?
- My equipment has been exposed to these conditions for, probably, 48-60 hours. Considering the APC unit has been supplying power to my computer, so it has never been directly exposed to the outlet, should I be concerned about damage (generally speaking, of course, and with no certainties)?

I appreciate any details anyone can offer about the above. Today the light has been off consistently, but I hope my APC unit will take the brunt of any outlet problems before my equipment does - is this a fair statement?

Thanks,E

[Anonymous user · Accepted solution]

An overloaded neutral can cause this.

I've experienced one case where the site wiring fault LED have been turning on very dimmly on a APC surge protector and I could only tell it was lit when the room was dark. I later found out that when the electrical shower (very common in my country) was on it caused a slight overload on the main neutral wire that goes to the circuit breaker panel and the voltage difference between neutral and ground could reach 2 volts even though they're bonded together at the electrical panel at the entrance of the house. Then I found out that if there is very small voltage differences between neutral and ground the site wiring fault LED will turn on, very dimmly though.

[BillP]

The light is most commonly caused by a bad ground. I would suspect that the colder weather might be affecting the ground connection in the outlet

[Anonymous user]

Hello, I have an APC ES (can further specify model if needed) on an old building with a monitor, desktop, and 2 small lamps hooked into it. This setup has been installed in the same outlet for about 6 months, and during the summer months when first installed, the site wiring fault light never came on. With colder weather, however, I have noticed on three occasions the following:

- The wire fault light was off, and the computer was running.
- Upon shut-down, I waited over 10 minutes to turn the computer back on, and have noticed that the fault light has come on.
- The second time this happened, the light has gone off by itself after 5-10 minutes of the computer being on.
- I have noticed that the light changes intensity, from a dim red to a bright red, as equipment has been turned on and off.

A few questions follow. If possible, answering all would be great:

- I dismiss a potential reverse polarity because, if so, the light would be on all the time. On another building, I actually experienced an outlet with reverse polarity, and the APC unit (an earlier model) had the site fault light on continuously.
- I suspect that cold weather might be at play. Each time this has happened, the room temperature was in the middle-upper 50s, if not slightly lower. For instance, last Saturday, the light was on during most of the day, and towards the evening, I decided to turn on the heating system. The next day, the light was gone.
- Could the above be a reason for the wiring fault light to come on? If so, what would be the possible reason why?
- My equipment has been exposed to these conditions for, probably, 48-60 hours. Considering the APC unit has been supplying power to my computer, so it has never been directly exposed to the outlet, should I be concerned about damage (generally speaking, of course, and with no certainties)?

I appreciate any details anyone can offer about the above. Today the light has been off consistently, but I hope my APC unit will take the brunt of any outlet problems before my equipment does - is this a fair statement?

Thanks,E