A related concern we have is with the combination of UPSs and GFCIs. Blindly plugging a UPS on to a GFCI protected socket defeats the protection the GFCI provides. We have the small/medium APC UPS across our campus, what is your opinion and recommendation on this moving forward?
As we see it, UPS protects the equipment and GFCI protects humans. So we need a consistent approach to establish guidelines of utilization of both. Are there GFCI-protected UPSs?
Let us know what you think. Please do the needful ASAP.
It is possible to use a UPS with a GFCI outlet, however due to the types of load attached to the UPS as well as the way UPS and surge products function, they do exhibit leakage currents. These currents are a natural result of the common mode filters present in computers and UPSs. These leakage currents may be large enough to "fool" the GFCI and cause it to trip. If this is what you are experiencing, you may need to replace the GFCI outlet or try a different brand/model. It might be worth following up with the vendor of the GFCI product to see if they have any models that they recommend for use in this type of environment.
This issue is documented in our knowledge base document #FA158850
You can access it here: http://www.apc.com/us/en/faqs/index?page=content&id=FA158850
Dear Liam, Thanks for your response.
While working Battery mode operation, How the GFCI can protect the UPS on downstream side to the connected loads. What is the safety for the humans?
What precaution have to take to protect the human from UPS exhibiting leakage current,while working on battery operation?
Let me know,the necessity steps to take?
Thanks in advance.
Liam is right.
We are electricians and we just change the GFCI outlet to GFCI type breakers if GFI is really needed. Most GFCI outlets were installed by the lowest bid contractor, using the cheapest labor, and lowest quality parts, and that was riding around in a van for a year. GFCI breakers are 100x more reliable.
Also, maybe reconsider placement of the UPS. Keeping the UPS is a fixed place, protecting only fixed loads, and in a secure setting reduces many of the issues that GFCI option protects against.
Dear Liam & Bob,
Thanks for your response,
Yes. You guys are right. I am accepting it, but i need a small clarification.
While on battery mode operation, If the leakage current is exceed the limit, How we can protect the human? In ups itself have any self protection to shutdown on loads?
Kindly reply me back.. Thanks in advance.
On battery mode the UPS will have a floating Neutral, which would likely trip any GFCI you were to plug into the UPS. These units are only designed for dry, climate controlled applications and should never be used near water, outdoors, or any place that you would traditionally use GFCI protection. I am not aware of any UPS manufacturer that has GFCI protection on the output.
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