20 amp 220v 10/2 UF installation

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KG5RPZ

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Pineville, Lousiana
Good evening folks, I have a simple question, I know the general answer to this question but not in the context of how I intend to install it.


I have a home office/ Ham Radio room. I have an amplifier that will need a 220v 20 amp power source, 10 years ago when I roughed in the walls of the office forseeing the need for potential growth in the future, I installed metal 4 square boxes with mud rings, and 3/4 in stub ups into the attic area of my house. I did this so it would be easy to fish something down the wall at a later time if it was ever needed.

I plan on using one of these conduits as a means for getting my 220v feed into the 4" box via the 3/4 conduit. Here is what I intended on doing. I want to install a 3/4 EMT male compression fitting over the 3/4" conduit, put a 3/4" coupling on that, and finally put a Romex connector snugly tightened into the 3/4" coupling. Now this is where the gray area is. I know that you cannot install UF or NM cable in conduit over 24" aka a thimble or nipple type scenerio. But the drop or full length of the conduit is 10' or 120", so if I was to strip out the last say 12' of my 10/2 UF wire would that be code compliant?

The reason I'm using the UF 10/2 wire is because it will go from the receptacle through the conduit, into my attic space and pop out where my service entrance feeds a sub panel inside the house. The UF cable will exit the attic at this location and be tie wrapped behind the 2" feeder for the sup banel until it gets to the outside 200 amp main breaker that has the 6 circuits and feed thru lugs for the sub panel inside my house. I'll then land the 10/2 inside the outdoor 200 main panel with feed thru lugs on a 20 amp double pole breaker, and ground it as required. The whole installation is temporary, Im building a 60x40 shop, and will have a 20' x 14' office/radio room in the new shop, but it might be 2 years before I get to that point.

So would this be code compliant if I strip the UF wire where it goes into the conduit? I assume the UF individual wires are THHN rated but I'm not certain.

I have worked in the Industrial world for so long, I really dont have a lot of working knowledge with Residential wiring methods and materials. We always run our circuits in rigid conduit, and pulled stranded cable at work. I have wired this house with a buddy over 15 years ago now. And it is all up to code, and I wanna make sure this addition is also safe and within the current code.

As an added bonus I have an outdoor TVSS, tied to the service entrance 200 amp disconnect panel an LEA type, and another TVSS at the sub panel Square D QO also Square D brand. So as you can see I'm the type to go far and beyond code and doing things right is my primary objective.

I could read the code book, and I could find the answer, but I know someone here already knows the answer to this question and rather than take a chance of me misinterpreting the code book, I'm here asking. But I do know what the code book is, how to read it, and where to find the information. If you wanna say I'm being lazy... I guess I'll be guilty lol...

Thanks in advance!
 
It is not compliant to strip the UF in the conduit. If you need room in he conduit then put a jb in the attic and run Thhn down the pipe.
 
20 amp 220v 10/2 uf installation

20 amp 220v 10/2 uf installation

The reason for stripping jacket wasn't intended for giving it more space, just to be compliant by not having it in the UF jacket inside the conduit. I dunno why I didn't consider the J-box alternative however, makes sense, and is an easy solution. I have some #10 THHN already and a J-box with cover I'll just mount the box on the stub up and support the box and conduit while we are at it. I have some Caddy clamp on bar supports I can attach to the J-box and the support means for the box itself.

I'd much rather work with #10 THHN stranded at the 4sq box in the wall anyway. I'll use crimp on connectors to attach the wire to the terminals on the receptacle.

Thanks for taking time to answer my question, in hindsight, I should have thought of this myself... Oh well, I was having a moment I assume.

Have a great weekend!
 
KG5RPZ said:
The reason for stripping jacket wasn't intended for giving it more space, just to be compliant by not having it in the UF jacket inside the conduit. I dunno why I didn't consider the J-box alternative however, makes sense, and is an easy solution. I have some #10 THHN already and a J-box with cover I'll just mount the box on the stub up and support the box and conduit while we are at it. I have some Caddy clamp on bar supports I can attach to the J-box and the support means for the box itself.

I'd much rather work with #10 THHN stranded at the 4sq box in the wall anyway. I'll use crimp on connectors to attach the wire to the terminals on the receptacle.

Thanks for taking time to answer my question, in hindsight, I should have thought of this myself... Oh well, I was having a moment I assume.

Have a great weekend!
Click to expand...


So yes you can sleeve the uf in the conduit, that is not an issue
 
20 amp 220v 10/2 uf installation

20 amp 220v 10/2 uf installation

Ok, thanks for the clarification, and you are absolutely correct again. That UF is one pain in the butt to strip out as I remember working with it years ago when I was an apprentice doing maintenance work for a friend of mine who owned an RV Park and their Sewer Lift Station....

Needless to say my rates went up dramatically if he called me and it was for the Sewer Lift Station... Most time's it was just an issue with the High limit, or the High High limit, but I told him back then... If that motor ever needs replacing, dont call me. HaHa!

Thanks again for taking time to respond to me!
 
May I point out that he may just run the UF wire down the conduit with a throat bushing on top, secure the UF within 6” of entering conduit , extend jacket of UF 1/4” within the box. No different than when doing receptacles in a basement when the conduit is used as a “sleeve” for protection or in his case a “chase”.

Or how about even just using a NM-to-EMT connector, then you could just strip the UF and run the conductors down the EMT.
 
mopowr steve said:
May I point out that he may just run the UF wire down the conduit with a throat bushing on top, secure the UF within 6” of entering conduit , extend jacket of UF 1/4” within the box. No different than when doing receptacles in a basement when the conduit is used as a “sleeve” for protection or in his case a “chase”.

Or how about even just using a NM-to-EMT connector, then you could just strip the UF and run the conductors down the EMT.
Click to expand...

Are the conductors in the UF marked? 310.120.
 
A step I understood the rule, the UF is marked and so the wires from inside it do not need to be marked. But, since it fits in a 3/4 conduit, not necessary to strip it. Just does not like more than one bend... know from experience.
 
Adamjamma said:
A step I understood the rule, the UF is marked and so the wires from inside it do not need to be marked...........
Click to expand...

Yes, they do. For the same reason you can't strip the wire out of NM and use it in a raceway.

310.120(B) Method of Marking.
(1) Surface Marking. The following conductors and cables shall be durably marked on the surface. The AWG size or circular mil area shall be repeated at intervals not exceeding 610 mm (24 in.). All other markings shall be repeated at intervals not exceeding 1.0 m (40 in.).
(1) Single-conductor and multiconductor rubber- and thermoplastic-insulated wire and cable
.....
(4) Underground feeder and branch-circuit cable
 
All conductors from cable assemblies are not permitted to be used in raceways unless individually marked with conductor type.

NM and UF - very rare you would find them with markings. MC cable - I have seen individual conductors marked (THHN, maybe even /THWN) at times, but not all the time.
 
20 amp 220v 10/2 uf installation

20 amp 220v 10/2 uf installation

Interesting concept about the inner UF conductors being marked or not. I ordered the cable from a company in New Orleans, way cheaper than I could buy it by the foot here locally. As luck would have it I needed 70' so it was buy a 100' roll and not need the 30' left over and add it to my hand coils I have in my junk room.

But I found a place online that was in the same state, so I ordered 70' and its coming next wednesday. I'll strip some of the outer jacket off and see if the conductors are marked or not. However I really liked the J-box on the end of the 3/4 stub up idea mainly because stranded wire is much easier to work with, the conduit is only 10' so it'll basically fall in anyway, but for making up the receptacle I'll use some stake ons rated for the amperage and tape the outside of the receptacle for an extra layer of protection with some super 33.

Initially I was going to change over from EMT with a male compression connector, to a coupling and thread a 3/4 Romex connector into the coupling, strip back about 12' of the UF cable and just push it down the 3/4 conduit. Which is how the question came to be about it being code compliant to do so, I knew they frowned on putting Romex, or UF inside conduit, unless it was just being used as a thimble or nipple and had to be shorter than 24".

I'm pretty sure I'll just use THHN #10 stranded from the J-box at the end of the EMT stub-up. I'll have to make sure the joints are solid and ground the box etc... but that's no biggie.
 
@KG5RPZ

There is no rule saying you can't put NM or UF in conduit with the exception that you can't use NM in a wet location. The inside of conduit installed outside is considered a wet location so you couldn't use NM for that. UF on the other hand, can be installed outside so you can run the UF in the conduit without stripping it. Before I would attempt to strip UF to go in a conduit I would just use another method such as has been mentioned.

Bottom line is UF can be ran unstripped in conduit!!!
 
Why use UF?

Why use UF?

If this is inside as you say it comes out of the conduit in an attic, why bother with type UF? Just use NM which is cheaper and easier to strip.

P.S. If it were me I would have used MC to feed a high power RF amplifier. The MC casing will act as a shield for any RF that gets on the AC feed. I think you can run MC inside EMT as well.
 
Andy Delle said:
If this is inside as you say it comes out of the conduit in an attic, why bother with type UF? Just use NM which is cheaper and easier to strip.

P.S. If it were me I would have used MC to feed a high power RF amplifier. The MC casing will act as a shield for any RF that gets on the AC feed. I think you can run MC inside EMT as well.
Click to expand...
The cable will exit the attic and be cable tied to a 2"conduit down the outside wall to a sub panel and land at a breaker there. It's a temporary installation.
 
20 amp 220v 10/2 uf installation

20 amp 220v 10/2 uf installation

Craigv is correct, as I initially stated this is a temporary install until I get my Shop built which will have specific wiring for various applications included in the planning of my Radio room / Technicians workbench / Home Office.

I decided to go with the J-box mounted to the 3/4 conduit, fasten the box to the nearest support structure in this case nearest roof truss. After having a moment to think about the purpose of the 240v circuit, I have decided to run the UF cable to the box, make joints inside the J-box and run a short piece of MC cable to the nearest prior installed J-box for general purpose power receptacle already wired and installed in the location.

The purpose of this is to get pick up a standard Grounding conductor that is tied into the existing sub panel that feeds the entire house. I will cap off the hot and the neutral on both ends and simply use the green to wire nut onto a equipment ground aka ground for the box, the conduit j-box etc. That green wire will bond with a pigtail at each J-box in this case 2, the one in the wall, and the one I'll be adding above the ceiling.

I'm going to buy a black, and red #10 stranded cable to connect to the UF wire in the attic, I will also buy one #12 green to be the typical equipment ground at both J-boxes. I'll buy a second ground #10 to be an Isolated ground since this will be used to power an RF amplifier in hopes of reducing noise and interference. I have an Isolated Ground Receptacle and the point of entry which is outside is the primary bonding ground or the typical source ground that would be used for an Isolated grounding system.

So for clarity here is how my 112 year old house is fed. Service entrance mast/ Meter center/ 200 amp trailer house disconnect with feed thru lugs and 6 circuits square D QO / feed thru lugs have 200 amp rated copper feeders supplying power and neutral to a Sub panel located inside the house. The reason for this is my 112 year old house has Solid 12" thick brick walls, with 1" of trailed on stucco over a screen grid fastened to the brick walls.

So as you can imagine installing a panel through the wall was impossible unless I wanted to look at a surface mounted 200 amp panel when I rewired the house. It was a 6 circuit knob and tube original wiring with the original panel located inside the house near where I have it mounted now.

So to be within the code, due to the distance I had to have a main 200 amp disconnecting means within 6" of the meter base, which could not happen as the wiring would have to be done, so rather than buy a 200 amp disconnect alone for about 300-400 dollars, I bought a Trailer house 200 amp disconnect with feed thru lugs, and had the additional 6 circuits so if I ever needed to add anything outside I could and it has come in handy because I later added Central air and heat, so the outdoor unit feeds from 2 of the 6 ckts in the outdoor 200 amp disconnect. I also have a GFCI mounted below the panel for various needs.

Dealing with a 112 year old home and the obstacles that come with it has been a challenge. So that's it in a nutshell, this is temporary as stated before, but I still want it up to code. I will route the UF from the entry point of my 2" feeder going to the sub panel inside the house run the uf behind the 2" pipe, which is mounted on unistrut tie wrap it with 1/2 tie wraps down 10' until it transitions via an LB into the 200 amp feed thru lug disconnect and or "Main" panel. Since this panel is the single point for all grounds it fits the criteria for being an Isolated ground point. So as long as I bond the attic box, and the wall box with a pigtail to the metal 4 square box and the new 4 square box in the attic, I'm covered for the equipment ground, and the isolated ground as well.

Thanks for everyone's input, I'm sure I'll be back when I get the shop project underway....

I intend on running my entire office off a sub panel fed from an isolation transformer, should be fun drawing that wiring diagram. I estimate I'll need a 30 KVA transformer to have enough power for the sub panel and the intent again is to reduce noise and transient voltages from surges. It will also be behind a TVSS, by LEA which uses a large MOV on a 30 amp double pole breaker. Why.... Because I'm an overkill specialist, and everyone would be disappointed if I just ran a regular power system in my new Ham shack! Haha!

Take care!~
 
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