SRT6KXLT not hardwired?

[BillP]

My U.S.-licensed electrician has proposed that he will wire a 50A breaker with 6AWG wire to a 14-50R receptacle where I intend to install an APC SRT6KXLT. He has stated that he will wire a 14-50P plug at the end of 6-foot electrical lead so the UPS can be disconnected and moved without calling him back.

I have read up on the topic and asked around as this model is meant to be hardwired. Specifically, I have read APC support (FAQ FA156549). The UPS model is not specifically mentioned in the FAQ and the unit has more than one output receptacle. This post suggests APC uses a relay to prevent backfeed on the input terminal. Is this relay present on the SRT6KXLT? Is there any other reason why adding an electrical lead to the SRT6KXLT is not advised? Finally, will this sort of installation void the warranty? 

[BillP]

Hi Critical,

I've looked up the SRT6KXLT and it is meant to be hard wired, the product page lists it as having a hard wired input and output. 

Here's the product page:

https://www.apc.com/shop/us/en/products/APC-Smart-UPS-SRT-6000VA-208V/P-SRT6KXLT

Here's the wiring and installation guide:

https://download.schneider-electric.com/files?p_File_Name=SUO%20IM%20990-5090F_EN.pdf&p_Doc_Ref=SPD_...

The SRT6KXLT-IEC is similar in that it has a hard wired input but IEC outputs. If you want any more technical details then I'd advise you to contact your local APC by SE support team, even if you haven't purchased the unit yet they should be able to help.

-Gavan

[BillP]

I appreciate the response but it does not answer my question. My licensed electrician has reviewed all of the wiring and installation guide. He states that it is not a big deal to add a lead but I can contact the local APC support team.

The issue is whether the input side of the UPS remains hot when it goes to "On Battery" mode because it is expecting, for example, a multiple earth neutral (MEN). It appears many APC SRT UPSs at least up until the SRT5KXLT have the relay referenced in the linked thread within my post. I don't see why it would not be present to meet the requirement of safety agencies (UL, VDE, etc.) but I need APC to confirm since they designed it and secured the safety approvals. Can anyone that you have access to respond to the question regarding the referenced relay being present on the SRT6KXLT?

Here is the thread again if you missed it: https://community.se.com/t5/APC-UPS-Data-Center-Enterprise/bd-p/datacenter-forum

[BillP · Accepted solution]

Hello - 

Yes, even though the SRT6KXLT is intended for hardwire input, it does have relays to prevent any backfeeding into the input wiring when on battery. Using the L14-50 as an input is fine as long as a licensed electrician performs the install. 50 amp plugs aren't that common, so all of our Smart-UPS units that require more than 30 amp input connections ship with hardwire terminals rather than a plug. They all meet the same UL standards for backfeed protection regardless of input.

Good question btw! 

Liam