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ScottR 06-02-2009 02:07 PM

Code compliance question: plug-in UPS inline with circuit
 
Hi All,

jerryh3 posted this link in another topic:

http://www.monoprice.com/products/pr...seq=1&format=2

Which reminded me that I wanted to ask if something similar that I did is code compliant:

http://www.codecrunchers.com/scott/p...S_injector.jpg

What I have is a 15A circuit wired with 14/2 going to the 2-gang box on top with the receptacles. The bottom box is wired with 2 14/2 cables behind the wall, each pigtailed to a #14 appliance cable/plug. The NM-B from the bottom box feeds 2 receptacle units in my den (LCD TV and equipment closet).

The above pic is from shortly after install, before I attached the UPS inline with the circuit, but you get the idea.

The boxes pictured are in my basement, ~5ft off the floor. The previous owner of the house finished the basement walls and ceiling with drywall but created an accessible raceway around the entire room -- there's an 8" gap between the wall and ceiling which is covered by stained 1/4" plywood that slips into a couple of dados in trim attached to the wall and ceiling. Best idea I've ever seen.

Gigs 06-02-2009 05:54 PM

We just did something like this at work.

We just used a romex clamp to hold a cord+plug pigtail into a box to plug into the UPS. The circuit was not connected to the mains power anywhere else except through the UPS.

I'm not sure your setup is OK. Could you show more pictures or explain how the things are connected better?


(Bottom line though is if you have stranded power cable in the wall, it's probably wrong and should be fixed)

ScottR 06-02-2009 06:14 PM

Quote:

Originally Posted by Gigs (Post 281813)
We just used a romex clamp to hold a cord+plug pigtail into a box to plug into the UPS. The circuit was not connected to the mains power anywhere else except through the UPS.

Sounds like we're on the same page; Same deal as mine, only I have 2 sets of cord+plugs feeding two branches. The only hardwired connection to the mains is in the box w/the receptacles.

Quote:

Originally Posted by Gigs (Post 281813)
I'm not sure your setup is OK. Could you show more pictures or explain how the things are connected better?

I'll get a pic of the inside of the bottom box for you. Pretty simple though; hot on one appliance cord is pigtailed to hot on one of the NM-B lines leaving the box, neut. to neut. Same thing for the other cord set. All grounds are bundled and bonded to the box.

Quote:

Originally Posted by Gigs (Post 281813)
(Bottom line though is if you have stranded power cable in the wall, it's probably wrong and should be fixed)

No no... The appliance cords are stranded, but they're pigtailed to NM-B in the box.

ScottR 06-02-2009 06:57 PM

http://www.codecrunchers.com/scott/p...or_openbox.jpg


The branch wiring comes in from the back of the box. (Yes, that cable clamp is listed for 2 14-2 cables). On the appliance cords I labeled the hot legs with black marker during original install.

So in the order of the wire nuts: Cord A hot, Cord A neut., grounds, Cord B hot, Cord B neut. Again, cord A feeds a receptacle in a closet, and cord B feeds a receptacle behind my TV. No unusual wiring beyond this point.

The grounds are hard to see; there are 5 pigtailed there -- one to bond the box + 2 x cord sets + 2 x branch wiring.


http://www.codecrunchers.com/scott/p...or_context.jpg


I took the above pic for context. Probably doesn't matter much, but I thought you might be curious.

It occurs to me that I probably should have bonded the two boxes together so that there is always a fault path -- there is none with both cords disconnected. Then again, there is no current either with the cords unplugged, so probably not that big a deal. (?)

hayewe farm 06-02-2009 09:32 PM

The only problem I can see is that the wires in the lower box could be plugged into a 20 amp circuit if avalible and because they are in wall 14 ga wires should be protected by a 15 amp breaker or fuse. I would guess at a minimum to be code compliant you would need to add 15 amp fuses or breakers to the lower box.

ScottR 06-02-2009 10:09 PM

Quote:

Originally Posted by hayewe farm (Post 281914)
The only problem I can see is that the wires in the lower box could be plugged into a 20 amp circuit if avalible and because they are in wall 14 ga wires should be protected by a 15 amp breaker or fuse. I would guess at a minimum to be code compliant you would need to add 15 amp fuses or breakers to the lower box.

That occurred to me, but there are no 20A receptacles within reach of those cords. Of course someone could theoretically run an extension cord from a 20A recept. to connect it, but being as I'm the only one who would be messing with it I'm comfortable with that being the case.

Also the cover for the lower box is labeled "15A Max Feed", so hopefully that would give it away if someone sneaks into my basement with an extension cord.. :wink:

Seriously though, if it's not compliant then I guess I could add a disconnect box w/15A breakers.

Just wondering why/if this product is compliant if my setup wouldn't be? http://www.monoprice.com/products/pr...seq=1&format=2 I'm not trying to be difficult, but I've seen it recommended a few times on this forum..

hayewe farm 06-02-2009 10:24 PM

It jumpers from one box to another with solid core wire with a perminate connection (You connect the two plates together with some solid core power cabling you can find at your local hardware store.) and must be sized to the circuit rating. In other words the solid core wire would have to be 12 ga if on a 20 amp circuit. I can see no advantage to it. You are basically installing and another box and connecting to and existing box what is the advanrage of the power cord? Your set up you have created an independent circuit with in wall wiring supplied by a plug in that could be connected to a larger capacity circuit. The in wall wiring must be protected. A couple of surface mounted glass fuse holders could be installed in the cover plate to meet the requirement.

ScottR 06-02-2009 11:04 PM

Quote:

Originally Posted by hayewe farm (Post 281963)
It jumpers from one box to another with solid core wire with a perminate connection (You connect the two plates together with some solid core power cabling you can find at your local hardware store.)

Right, same as I have..

Quote:

Originally Posted by hayewe farm (Post 281963)
and must be sized to the circuit rating.

Not true. The mfrs. of both products on the market (Powerbridge and DataComm) recommend 14-2 (in DataComm's case "or 12-2") wiring and do not specify that it needs to be sized to the supply circuit. Also both companies include a #14 patch cord to be used. Their inlets are also rated for 15A.

http://www.datacommelectronics.com/product.php?ID=440
http://www.powerbridgesolution.com/a...swarranty.html

That being said, I think that both products could be used as-is unsafely on a 20A circuit, which is not a good thing.

Quote:

Originally Posted by hayewe farm (Post 281963)
I can see no advantage to it. You are basically installing and another box and connecting to and existing box what is the advanrage of the power cord?

The advantage is that I can have a UPS and/or voltage regulator for my sensitive electronic equipment, and have it tucked away in my basement. Putting a UPS in my equipment closet would have been no problem, but I wasn't going to mount one on the wall next to my LCD TV. :no:

Quote:

Originally Posted by hayewe farm (Post 281963)
Your set up you have created an independent circuit with in wall wiring supplied by a plug in that could be connected to a larger capacity circuit. The in wall wiring must be protected. A couple of surface mounted glass fuse holders could be installed in the cover plate to meet the requirement.

I'm not disagreeing with you at all. I agree completely, actually.

I'm still lost as to how there wouldn't be the same requirement for the PowerBridge kit and the DataComm kit. Unless those would both technically violate code when installed with the included parts, but the responsibility for that falls on the installer and not the mfr.??

theatretch85 06-03-2009 12:02 AM

Quote:

Originally Posted by ScottR (Post 281709)
The previous owner of the house finished the basement walls and ceiling with drywall but created an accessible raceway around the entire room -- there's an 8" gap between the wall and ceiling which is covered by stained 1/4" plywood that slips into a couple of dados in trim attached to the wall and ceiling. Best idea I've ever seen.

Could you please either PM me with pictures or post them here of this setup? I am very interested in how they did that as I am finishing off the ceiling in an area where I will be running network and CATV cable through the basement and have considered doing something like what you are describing.

On topic - You could always steal some 15 amp circuit breakers out of some power strip and mount those in your bottom box. I built a "heavy duty" power cord tap a while back that was fed with a 30 amp twist lock to a junction box with a duplex outlet mounted to either side of it. Put a 4" j-box cover on the box in the middle and installed the 2 15 amp breakers to protect the outlets (and the very short pieces of 12 gauge wire I used between the boxes). The power strips are pretty cheap, and would certaintly be cheaper than a fused disconnect.

hayewe farm 06-03-2009 09:45 AM

Patch cord, fixture wiring, and panel wire have different wire size requirements than in wall wiring. 15 amp outlets can be used on 20 amp circuits. As long as the wiring between the two mentioned devices are 12 ga it would be code compliant because the cord has a plug that will only work on 15 or 20 amp outlets. The in wall wiring becomes part of a branch circuit and a branch circuit must be protected by a breaker that matches the smallest wiring in the branch. For instance, if you run 12 ga from the panel to 4 outlets in your living room then come off one of the receptacles to a switch and a light with 14 ga wire then the circuit is a 15 amp branch and must be protected by a 15 amp breaker.

Because these two units have a patch cord that can be plugged into a 15 or 20 amp circuit the in wall wiring between the units would have to be either 12 ga or 14 ga and protected by a 15 amp breaker. The external components like patch cords or fixtures do not affect the requirement. In wall wiring must be protected from the source by an appropriate sized breaker.

Now whether an inspector would catch it or not is another story.

Gigs 06-03-2009 10:46 AM

1 Attachment(s)
Here is what we did

The one on the right is a real outlet... the one on the left plugs into the UPS and is unpowered. It continues on to another set of UPS protected outlets.

Gigs 06-03-2009 10:49 AM

Quote:

Originally Posted by hayewe farm (Post 282102)
In wall wiring must be protected from the source by an appropriate sized breaker.

His UPS likely has built in overcurrent protection. And it's very doubtful his UPS could supply more than 15 amps unless it's really big for a home UPS.

hayewe farm 06-03-2009 11:17 AM

Quote:

Originally Posted by Gigs (Post 282133)
His UPS likely has built in over-current protection. And it's very doubtful his UPS could supply more than 15 amps unless it's really big for a home UPS.

If it were hard wired to the UPS with 15 amp breaker it would be no problem but it is feed by a patch cord that can be plugged into the UPS, another outlet, an extension cord, or a generator. The question is not is it safe the way he will use it the question is is in compliant and in my opinion it is not. You can plug it into a 100 amp service if you want and it would work but it still wouldn't be compliant.

Gigs 06-03-2009 12:36 PM

I see what you are saying...

I could see an inspector potentially having a problem with a 14 gauge fixed wiring system being powered off an 5-15 inlet or whip. I could also see them letting it slide.

He could fix the problem by finding an extension cord with a 15 amp fused plug and using that for his whip, I'd say.

Gigs 06-03-2009 12:43 PM

BTW Scott I just noticed your UPS... it's tiny! Be careful not to overload it, that kind is only good for maybe 3-4 amps.


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