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

APC UPS for Home and Office Forum

Schneider Electric support forum for our APC offers including Home Office UPS, Surge Protectors, UTS, software and services and associated products designed to share knowledge, installation, and configuration.

Solved
Corporal_G_apc
Crewman
Crewman
0 Likes
3
202

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

This was originally posted on APC forums on 2/1/2010


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


Accepted Solutions
rau_apc
Commander
Commander
0 Likes
0
202

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

This was originally posted on APC forums on 2/3/2010


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.

See Answer In Context

3 Replies 3
rau_apc
Commander
Commander
0 Likes
0
203

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

This was originally posted on APC forums on 2/3/2010


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
Administrator Administrator
Administrator
0 Likes
0
202

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

This reply was originally posted by Jon on APC forums on 2/5/2010


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

Corporal_G_apc
Crewman
Crewman
0 Likes
0
203

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

This was originally posted on APC forums on 2/1/2010


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