Joining 6/3 Romex to THWN

[overland04]

I'm wondering the proper procedure for joining a run of 6/3 indoor to the THWN running outdoor to my detached garage.

As of now I have nothing but the conduit run between my detached and home (5ft). I plan to run 6/3 romex from my main panel (33ft) to a junction box on the interior wall of my basement. From the J-Box is 1" conduit that was ran to the outside, underground, then into the detached garage sub-panel. I plan to run 6ga THWN in the conduit to the sub-panel.

My question is, that in the junction box, what is the proper way to join the THWN and Romex together?

(the neutral has be isolated form the sub-panel and grounding rod has been driven and mounted to a lug in the panel already)

Thanks!

- Jason

 

[Spudland_Dave]

WWDD...Run the 4 conductors of #6 THWN solid from panel to panel...run conduit from the J-Box to your main panel...if solid conduit isn't a possibility, use the Carflex stuff.

 

[rlitman]

Polaris connectors, or split bolts. Either way, you will need a pretty large box to fit those splices.

 

[overland04]

WWDD...Run the 6-3 THWN solid from panel to panel...run conduit from the J-Box to your main panel...if solid conduit isn't a possibility, use the Carflex stuff.

I can run THWN for the entire run. Locally I found that the 6/3 is cheaper but to run conduit the entire way isn't a big issue, my basement is still open.

On #6, can I run a single color with phase tape to avoid buying three different spools of THWN?

 

[wyliesdiesels]

Polaris connectors, or split bolts. Either way, you will need a pretty large box to fit those splices.

+1^

Just be aware that you are limited to a 60a breaker(next standard size; #6 NM-B has 55a ampacity) because of the Romex, even though the THWN can be protected by a 70a breaker(65a ampacity).

I can run THWN for the entire run. Locally I found that the 6/3 is cheaper but to run conduit the entire way isn't a big issue, my basement is still open.

On #6, can I run a single color with phase tape to avoid buying three different spools of THWN?

You can do whatever u want but reidentifying grounded conductors(neutral) and EGCs(grounds) sizes 6 and smaller is NOT code approved, though it is done all the time. If you are getting inspected, the inspector may or may not fail it, though most inspectors dont even notice this violation...

 

[overland04]

+1^

Just be aware that you are limited to a 60a breaker(next standard size; #6 NM-B has 55a ampacity) because of the Romex, even though the THWN can be protected by a 70a breaker(65a ampacity).

You can do whatever u want but reidentifying conductors sizes 6 and smaller is NOT code approved, though it is done all the time. If you are getting inspected, the inspector may or may not fail it, though most inspectors dont even notice this violation...

The sub panel will be an 100a and the feeder will come off a 60a in the main panel.

I definitely don't want to run into any code violations. For the extra cost of buying 3-100' spools of wire isn't close to the cost and headache of a pissed off inspector.

Black, Red, White is #6, What size is the bare ground? #10?

Thanks again for the help!

 

[pattenp]

My understanding is that the no remarking of #6 or smaller applies only to the equipment grounding conductor.
It's okay to mark a white as red or black, but not as green. You're to use a green only as a ground and are not to mark it as an ungrounded conductor.

+1^

You can do whatever u want but reidentifying conductors sizes 6 and smaller is NOT code approved, though it is done all the time. If you are getting inspected, the inspector may or may not fail it, though most inspectors dont even notice this violation...

 

[pattenp]

#10 Cu for the ground is fine for up to 60A.

Black, Red, White is #6, What size is the bare ground? #10?

Thanks again for the help!

 

[Highbeam]

I did the exact install you are proposing. I had a 6/3 romex from my main panel that fed a welder plug on an exterior wall of my home close to the new outbuilding. I removed the welder plug, installed a big junction box, and then ran 2" conduit from the new J-box all the way into the new subpanel at the outbuilding. The new subpanel has a 100 amp inlet breaker, the old welder circuit had the 60 amp breaker protecting the 6/3.

Anyway, I switched from romex to THWN in that junction box using the all metal **** connectors with set screws covered with heat shrink sold in a kit at home depot. If I could do it over, I would have paid for the polaris connectors. If you look, you can buy wirenuts rated for 2 #6 wires but I tried them and they ****.

If you can go all the way to the main panel with wire, or even conduit then I would be running new continuous wire capable of feeding the full 100 amps.

Oh and 1 inch conduit is pretty small. To feed your 100 amp subpanel I would be using at least 2".

 

[wyliesdiesels]

My understanding is that the no remarking of #6 or smaller applies only to the equipment grounding conductor.
It's okay to mark a white as red or black, but not as green. You're to use a green only as a ground and are not to mark it as an ungrounded conductor.

Whoops! I was typing so fast I left out the key identifier- grounded conductor and EGCs. I edited my post.

I just reread through 200.6 and while it doesnt say that a grounded conductor smaller than #4 cant be reidentified, it does say that it needs to be identified by 3 white strips along its entire length, which is a pain in the *** for longer cables. For grounded conductors #4 and larger, the previous will work or the cable can be marked with white tape at the termination points! Now Im curious why conductors smaller than #4 cant be taped in the same fashion.

OP- u can use black for both of the hot legs and the neutral, which in addition needs to be taped as I mentioned above but the #10 HAS to be green jacketed! So just buy one roll of black and a whole lotta white tape and a roll of green!

 

[Highbeam]

As of now I have nothing but the conduit run between my detached and home (5ft). I plan to run 6/3 romex from my main panel (33ft) to a junction box on the interior wall of my basement. From the J-Box is 1" conduit that was ran to the outside, underground, then into the detached garage sub-panel.- Jason

We're talking about a 5 foot run of conduit here. Maybe 10 feet of THHN. Go buy it by the foot at HD in any color that you want.

 

[overland04]

We're talking about a 5 foot run of conduit here. Maybe 10 feet of THHN. Go buy it by the foot at HD in any color that you want.

Originally I was going to connect Romex to THWN. That run of THWN would be minimal footage maybe 10-15ft total. In the lower posts they were recommending me to run THWN from the main panel back which would be closer to 60ft. It would be a nice option to buy 1 spool instead of 4 separate spools.

 

[Highbeam]

Originally I was going to connect Romex to THWN. That run of THWN would be minimal footage maybe 10-15ft total. In the lower posts they were recommending me to run THWN from the main panel back which would be closer to 60ft. It would be a nice option to buy 1 spool instead of 4 separate spools.

You don't need to run THWN to the main panel. That's a lot of extra work and expense if you already have romex within 5 feet of the subpanel. We're talking 50 extra feet of conduit, 3-#6 coppers, and a ground.

You do not need to buy wire by the spool. You can buy it by the foot in all the right colors at your local home depot.

What's wrong with the existing romex in your house?

 

[overland04]

You don't need to run THWN to the main panel. That's a lot of extra work and expense if you already have romex within 5 feet of the subpanel. We're talking 50 extra feet of conduit, 3-#6 coppers, and a ground.

You do not need to buy wire by the spool. You can buy it by the foot in all the right colors at your local home depot.

What's wrong with the existing romex in your house?

There isn't 6/3 run yet. The original plan was to run 6/3 romex from the main panel to a junction box where it would meet the conduit that is ran to the detach. If I was to use romex, I wasn't sure how to connect the junction between the romex and THWN that is running through the conduit.

Someone suggested to run THWN from the main panel out to the garage sub-panel so there isn't a splice. Both ideas would work, just didn't know what would be the proper cost-effective way to do it.

Thanks for the help

 

[wyliesdiesels]

I think your idea of romex inside is to avoid running conduit in your house right?

 

[overland04]

I think your idea of romex inside is to avoid running conduit in your house right?

Not necessarily, I'm up for anything that is code, makes sense and is cost effective. The run from my main panel to the conduit and into the garage is completely open.

 

[pattenp]

Use the romex and THHN with splice reducers. Either tape up the splice well or use shrink tube. Just use a large enough jbox to give yourself working room to fold the wire into the jbox.

Splice/Reducer

 

[zmaxmotorsports]

Split bolts and 3m rubber splicing tape followed by super 33

 

[overland04]

Use the romex and THHN with splice reducers. Either tape up the splice well or use shrink tube. Just use a large enough jbox to give yourself working room to fold the wire into the jbox.

Splice/Reducer

Split bolts and 3m rubber splicing tape followed by super 33

Either way sounds good to me. I can grab a 6x6x4 Junction Box to hold it all.

 

[theoldwizard1]

Either use friction tape (3M 1755) or rubber splicing tape.

Is is no place for the HF 10 for a $1 tape !

 

[tfi racing]

Only 50-60' total?Around here we would just spend a few more $$ and just run 6/3 NMWU the whole length,cheaper and easier than JB's,connectors,tape and the labour for the transition from one wire to another.

 

[overland04]

Only 50-60' total?Around here we would just spend a few more $$ and just run 6/3 NMWU the whole length,cheaper and easier than JB's,connectors,tape and the labour for the transition from one wire to another.

This option sounds good too. I found it online for $270 for 125'. All around it seems like the easiest. I know it's good for direct burial, but am I okay with running it through the existing conduit? I have a week left before the driveway goes in so I can change the conduit if needed to a 2"

 

[Spudland_Dave]

Only 50-60' total?Around here we would just spend a few more $$ and just run 6/3 NMWU the whole length,cheaper and easier than JB's,connectors,tape and the labour for the transition from one wire to another.

Agreed...as mentioned in my first response, I'd try to go for a single piece of wire if at all possible...in this case it sounds very simple/easy. Sure you may save a few bucks on the Romex vs THWN, BUT all the split bolts/Polaris connectors/etc cost pretty good money, add work and introduce a point of failure.

ALL That said...is there a reason you cant or don't want to go with something like #2 AL or such? #2 AL wire (Romex or MHF) is MUCH cheaper then 6-3 and gives you a 90amp panel instead of a 50A panel.
Yes, if you go with the MHF, you'd need to transition to SER in the living space...so all the above answers for transitioning would be correct..

 

[overland04]

Agreed...as mentioned in my first response, I'd try to go for a single piece of wire if at all possible...in this case it sounds very simple/easy. Sure you may save a few bucks on the Romex vs THWN, BUT all the split bolts/Polaris connectors/etc cost pretty good money, add work and introduce a point of failure.

ALL That said...is there a reason you cant or don't want to go with something like #2 AL or such? #2 AL wire (Romex or MHF) is MUCH cheaper then 6-3 and gives you a 90amp panel instead of a 50A panel.
Yes, if you go with the MHF, you'd need to transition to SER in the living space...so all the above answers for transitioning would be correct..

Not too familiar with AL cable but it seems that with any combo of Aluminum, I would have to split it. It's looking like the 6/3 UF is going to be my best choice. I can change the conduit to 2" so the pull is easier between the house and detach and I'll be running one solid run from the Main to the Sub.

Also, my basement has a dirt floor so having the UF cable ran might be a good option anyway.

Sound okay?

 

[Highbeam]

What about the conduit size? Is 1" big enough for 3-#6 coppers plus the #10 ground? For the small extra expense, I would recommend a larger conduit, say 2", so that you would have an easier time pulling the wire but also to allow future upsizing.

 

[overland04]

What about the conduit size? Is 1" big enough for 3-#6 coppers plus the #10 ground? For the small extra expense, I would recommend a larger conduit, say 2", so that you would have an easier time pulling the wire but also to allow future upsizing.

Yes, in the above post I mentioned that I can change up to a 2" before I have the driveway paved next week. I've never worked with UF before but I'm thinking it will be easier to pull through 2" and maybe wouldn't fit at all through the 1"

Thanks!

 

[wyliesdiesels]

This option sounds good too. I found it online for $270 for 125'. All around it seems like the easiest. I know it's good for direct burial, but am I okay with running it through the existing conduit? I have a week left before the driveway goes in so I can change the conduit if needed to a 2"

MHF depending where bought can be way cheaper than 6/3 UF-B. The UF-B can be run through conduit but 1" will be a bare. I would go with 2".

Agreed...as mentioned in my first response, I'd try to go for a single piece of wire if at all possible...in this case it sounds very simple/easy. Sure you may save a few bucks on the Romex vs THWN, BUT all the split bolts/Polaris connectors/etc cost pretty good money, add work and introduce a point of failure.

ALL That said...is there a reason you cant or don't want to go with something like #2 AL or such? #2 AL wire (Romex or MHF) is MUCH cheaper then 6-3 and gives you a 90amp panel instead of a 50A panel.
Yes, if you go with the MHF, you'd need to transition to SER in the living space...so all the above answers for transitioning would be correct..

Not true. MHF, if dual rated withh RHH rating, can be run inside but needs to be in conduit because there is no outer sheath.

What about the conduit size? Is 1" big enough for 3-#6 coppers plus the #10 ground? For the small extra expense, I would recommend a larger conduit, say 2", so that you would have an easier time pulling the wire but also to allow future upsizing.

It will be a bare to pull.

Not too familiar with AL cable but it seems that with any combo of Aluminum, I would have to split it. It's looking like the 6/3 UF is going to be my best choice. I can change the conduit to 2" so the pull is easier between the house and detach and I'll be running one solid run from the Main to the Sub.

Also, my basement has a dirt floor so having the UF cable ran might be a good option anyway.

Sound okay?

What do u mean by "split it"?

 

[overland04]

What do u mean by "split it"?

Below was the only reason I mentioned to splice, or my incorrect use of (split it) whoops!

So you can run MHF #2 AL the entire run? Just need it in a conduit?

ALL That said...is there a reason you cant or don't want to go with something like #2 AL or such? #2 AL wire (Romex or MHF) is MUCH cheaper then 6-3 and gives you a 90amp panel instead of a 50A panel.
Yes, if you go with the MHF, you'd need to transition to SER in the living space...so all the above answers for transitioning would be correct..

 

[wyliesdiesels]

Below was the only reason I mentioned to splice, or my incorrect use of (split it) whoops!

So you can run MHF #2 AL the entire run? Just need it in a conduit?

Yes as long as the MHF has an RHH rating. Yes it needs to be in conduit inside because there is no outer sheath. But it can be direct buried.

 

[Spudland_Dave]

Not true. MHF, if dual rated withh RHH rating, can be run inside but needs to be in conduit because there is no outer sheath.

Touché... I didn't get TOO deep into details, but you are correct...My garage feed (approx. 100' total) is a single uninterrupted run of #2 AL from panel to panel..

Pricing changes, and the pricing I am about to list spans 6 months (bought the MHF last fall, 6-3 this spring), but I'll just throw this out there.. the #2 AL MHF was +/- 1.25 a foot, the 6-3 I bought for my welder outlets was right around 2.00/ft. Even factoring in the cost of the Conduit for your interior portion, it would still be cheaper if not the same price either way and with the AL you have a 90A panel vs a 50A Panel.

 

[overland04]

Touché... I didn't get TOO deep into details, but you are correct...My garage feed (approx. 100' total) is a single uninterrupted run of #2 AL from panel to panel..

Pricing changes, and the pricing I am about to list spans 6 months (bought the MHF last fall, 6-3 this spring), but I'll just throw this out there.. the #2 AL MHF was +/- 1.25 a foot, the 6-3 I bought for my welder outlets was right around 2.00/ft. Even factoring in the cost of the Conduit for your interior portion, it would still be cheaper if not the same price either way and with the AL you have a 90A panel vs a 50A Panel.

Thanks Dave and thank you all for the advice.
The final plan is to run #2 AL MHF in 1-1/2" conduit the entire run from panel to panel. I purchased 100' at HD for $1.41ft plus 2 ground rods, sub-panel, conduit, LB's and a few 90 degree elbows.

I'm keeping the existing 1" as an open conduit for future cabling and adding the 1-1/2" for the MHF.