Is there a safe and compliant way to run consumer UPS power through house wiring to an outlet?

Question

I would like to remove an existing cable from the breaker panel, that feeds a single home run outlet, and wire it to a consumer UPS that I will locate near the panel, through a junction box.

Questions:

1. To join the power cord from the UPS to the junction box can I put a NEMA 5-15 inlet on the box and use a consumer power cord?
2. Instead of a NEMA inlet (a) could I do it with an IEC C14 inlet? (b) could I just insert a consumer power cord into the box with strain relief and splice wires inside the box? This would all be on the surface near the breaker panel, nothing inside walls but also no conduits.
3. As a further optional step, if the junction box additionally is fed raw power and I add a switch to bypass the UPS, can I just switch the hot or must the neutrals be switched too? The grounds? I assume the UPS input and output grounds are bonded but I don't know about the neutrals. The inlet hot would never be connected to the raw power hot, but is there still any unacceptable danger in this arrangement?

This question is instructive but the answers focus on the practicality of running new cable from room to room. My situation is to use existing, to-code, wiring from the basement to the room, and adds the idea of switching to raw power.

Answer 1

Yes.

You can run an isolated electrical line, using normal in-wall wiring methods, from a single inlet to outlets.

The inlet will need to be in the NEMA family. A C13 inlet won't cut it for at least 2 reasons off the top of my head: first it lacks the necessary ampacity, and second it is voltage-agnostic, and the inlet needs to be keyed to reject a power source of the wrong voltage.

As far as having a built-in switch, same rules apply as for a generator. You must have exactly one neutral-ground bond in the entire system. Not zero, not two. ("two" is its own special kind of 'bad'). If the power source bonds neutral and ground, then you must switch neutral. If it does not, then you must not.

The best bet is to switch neutral, but not bond neutral around the switch - have the isolated circuit draw neutral only from the switch. These types of switches are expensive, so I'd just do cord-and-plug myself.

You would never have a reason to switch safety ground.

Answer 2

Here I'm planning a nice implementation of the advice in the accepted answer. This plan provides raw and UPS power to the basement location and also through existing house wiring to a den outlet. It includes a UPS bypass switch allowing for UPS service.

The trick was to find a DPDT switch that would switch live and neutral at reasonable cost, and an inlet, both of which would fit in a standard multigang box with some feasible cover arrangement. I could have done it with sectional box covers for about the same price but this plan uses a standard 4-gang Decora plate. It's easier to build and looks better.

It's all limited to 15A, which works perfectly for what I'm planning.

The key is two devices I found:

• The Leviton 5686-2W switch. This is a 15A DPDT switch. It's intended use is to switch 2-pole power between two devices, but it works here. And this specific model is in Decora profile and costs less than $50.
• The Midlite 4642-W recessed inlet. It's intended use is to connect a knee-height outlet to a shoulder-height TV routed through a power conditioner at the lower level. But it's perfect here because it completes the project without requiring a special cover plate.

The Midlite inlet requires a deep box so I've included a Raco 698, and I'll also replace the den outlet with a red one and put a switch guard over the switch.

The outstanding problem is to pick a UPS that does all the things I want at reasonable cost. Probably time for some illusions to be shattered.

Here's the design:

Answer 3

You could install one of these upstream of the outlet: https://ezgeneratorswitch.com

I am not affiliated with them in any way.