exterior EGC splice question

[JCByrd24]

Need code clarification from an electrician. I'm getting ready to install a solar PV system which is an ungrounded DC system (solaredge). As such I need to run only + and - DC lines and a EGC from the array on the roof to the inverter. DC lines will be continuous 10 awg PV wire (USE-2/RHW-2 with extra insulation) from array to the inverter (overkill but included in my kit and eliminates a junction to THWN-2 or similar). The EGC on the roof is typcially 6awg solid bare cu between panels and racking and needs to go to stranded 6 awg inside the conduit. I was planning on using a NEMA 3R rated rigid LB conduit body (with EGC bonded with ground bushing) mounted solidly to rigid conduit through proper conduit roof flashing for the roof penetration (transitioning to EMT inside). The issue is I cannot legally splice inside a 3/4" or even 1" LB due to fill limitations. I could go to 1-1/4" to get the space I need but I see no reason why I cannot splice the EGC just outside the LB with a listed split bolt since the wire is (I believe) allowed to be bare, spliced, and outside anyway but I wanted to double check. I have no one to please that I know of; the local codes guy does not do electrical inspections so I don't imagine he'd be of much help with questions. I understand I could use a true box, but they cannot be conduit supported and thus would require less straight forward flashing details. Also, most exterior boxes seem less watertight than the LB would be. There is a box specifically made for this application, but at $70 I think it's overkill. Look forward to your input.

Edit: I think I realized that with 2x10awg + 1x6awg EGC I need 1" LB for most manufactures anyway, so at that point I could just go up to 1-1/4" and bush down, but now I'm just curious.

Edit: Ok, I have now confirmed I believe that my EGC splice does not require counting the conductor twice as a current carrying conductor would. As such the 1" LB will work assuming the selected splice fits nicely inside. I'm still curious though if it would not be safer to put the EGC splice outside the LB. Assuming for example a split bolt (sharp edges) and the far fetched assumption of vibration in this location, the split bolt could cause more damage to the conductors in the box than outside.

 

[unsinkable]

First off, kudos for considering your code compliance even though there's no electrical inspector...my in-laws are up your way and i've seen some pretty scary wiring up there !
Why don't you just continue the 6 solid down the RMC until you reach the jb/emt ? Is it a straight run ?
For that matter, you can run stranded for bonding and ground conductors, then conduit end to end.

 

[JCByrd24]

Thanks for the reply. I was thinking the LB on the roof would be the only box until the inverter. The run isn't straight physically but this is a dedicated run with only these conductors. I will have pull elbows but no boxes. I was going to transition to EMT just below the roof (one 12" or so section of RMC threaded into the LB > RMC coupling > EMT threaded coupling>EMT). Perhaps that is not legal and I was only assuming the threads matched I have a note the check that. Though come to think of it they sell a transition coupling, kinda rare though.

Are you saying use the conduit as the ECG? That isn't kosher for PV installs, must be a separate EGC conductor and it must be in the conduit. Or are you saying just run the stranded EGC within the array as well, no EGC splice? I thought of that and I think it's legal but common practice is bare solid up there, better connections at the array points and more resistant to damage/corrosion. I would be using green THWN-2 rated wire and even though it's not rated for outdoors my understanding is it's ok because the insulation is superfluous.

 

[unsinkable]

yes, run the stranded the whole way. No splice needed.
Stranded is often used on roof as well.