Building Wiring Fault light

[Anonymous user]

I have an APC Smart-UPS Online UPS (APC SMART-UPS RT 1500VA 120V Tower, SURTA1500XL).

I also have a spare rackmounted APC surge protector (APC Black Rackmount SurgeArrest 9 Outlet 120V, NET9RMBLK) to which some switches are connected.

When I connect the surge protector to one of the outlets on the UPS, the red "Building Wiring Fault" light on the surge protector is lit.

However, when I connect the surge protector directly to one of the wall outlets, the red "Building Wiring Fault" light goes away.


1> The UPS is grounded for sure and there is no wiring fault light on the UPS itself, so why would the surge protector (which is connected to the outlets on the UPS) indicate that there is a wiring fault?

2> Is that a real wiring fault that I should be concerned about? Is the surge protector (which is connected to the UPS) still grounded and still offer the necessary surge protection for devices connected to it?


One may question why I have it set up that way. The reason I am connecting the rackmounted surge protector to a UPS is because I cannot afford to buy another PDU for now and because of the limitations of the lengths of the existing power cords. The surge protector is the only one that could reach that far, so I am using it as a poor man's PDU of a sort.

And no, I cannot move the UPS and the switches any closer to one another.

Is there any down side to doing it this way? Is that wiring fault light on the surge protector a real concern?

Thanks.

[Anonymous user]

Hi clarkson,

The wiring fault LED on the surge protector always lights up when plugged into the UPS.

I had also tried removing the surge protector from the rack and plugged it into a Smart-UPS 1000 in another closet, and the wiring fault LED on the surge protector also lit up.

The light went away whenever I plugged the surge protector directly to the wall though.


On a separate possibly unrelated note, the wiring fault LED (of the UPS unit itself) is not lit on either UPS.

[Anonymous user]

Thanks. I don't have a voltmeter readily available, but I will try to find (or buy) one and get the measurements.

In this instance, what is the range of the AC voltage I should expect to see for Neutral-Ground on the receptacle? Just asking in case I get my hands on an older manual-ranging voltmeter or multimeter.

[Anonymous user]

Hi clarkson,

I finally measured the AC voltage for the wall outlet, the receptacles on the SmartUPS RT 1500, the receptacles on the SmartUPS 1000. They are as followed:

1> Wall Receptacle:

Hot-Neutral: 121.8 V AC
Hot-Ground: 121.5 V AC
Neutral-Ground: Approximately 0.776 V

2> Smart-UPS 1000:

Receptacle # 1:

Hot-Neutral: 118.2 V
Hot-Ground: 119.7 V
Neutral-Ground: Between 1.864 V and 2.256 V

Receptacle # 2:

Hot-Neutral: 117.6 V
Hot-Ground: 119.7 V
Neutral-Ground: Between 1.739 V and 2.230 V


3> SmartUPS RT 1500

Receptacle # 1:

Hot-Neutral: 119.4 V
Hot-Ground: 121.5 V
Neutral-Ground: Between 0.619 V and 0.630 V

Receptacle # 2:

Hot-Neutral: 119.4 V
Hot-Ground: 121.5 V
Neutral-Ground: Between 0.820 V and 0.846 V


None of the Neutral-Ground voltage of the UPS outputs ever exceeded 2.5 V, so I'm not sure why that fault LED would light up when the suppressor is plugged into the UPS.

Thanks.

[Anonymous user]

Based on those voltage readings, is it still OK to leave the surge suppressor plugged into the UPS even with the Building Wiring Fault LED on? Will the switches connected to the surge suppressor still be protected? Or should I just plug the surge suppressor directly into the wall just to play it safe?

Thanks.

[Anonymous user · Accepted solution]

I received a power conditioner with the BWF on. I plugged it into an APC surge protector with a BWF and the light on the surge protector is not lit, but the light on the power condition is still lit. This tells me I received a defective power conditioner.

Any idea how I can fix it?