Spa Wiring

I was reading some threads here and see good feedback to questions asked.

I am adding a 240v 50 amp circuit for a 2 year old spa I just bought.

Off my 100amp main service panel I have a 70 amp sub. (Square D QO, installed and inspected under building permit) I plan to put a Square D QO 50amp 2 pole breaker here and run 6AWG 3 wire (2 hot, 1 neutral, 1 bare) Romex under the house to the junction box where it will go through the wall. The under the house run is about 70'.

Q1) I have read that an LB is required for the through wall connection, what is this? Is it just a 90 degree connector with a access door?

Outside I will run 4 insulated conductors, 2 hot 6AWG, 1 neutral 8AWG, and ground 8AWG (all insulated). These will be inside 3/4" schedule 40 PVC conduit secured under a wood/Trex deck. No exposure to the sun approximately 6" off the ground.

Q2) Is is OK to run 8AWG for neutral and ground or could I go with 10AWG, or do I have to stick with 6AWG? The outside cable run is about 20'.

Q3) Can I strip the sheath off the 6AWG Romex to use as insulated conductors in the PVC conduit (under a deck)? The ground would be a new green THHN conductor.

Once outside I will run through a Square D QO 50amp GCFI "Spa disconnect", mounted on the outside of my house. Nice plastic rain proof enclosure. This will be about 13 feet from the spa in direct line of sight.

Q4) Does this box have to be 48" above the deck?

The PVC will connect to a piece of water tight flex conduit less than 6' long to enter the spa enclosure and connect to the controller.

Any help would be appreciated.

I did some research and found some of my own answers (be they right or wrong) and have a further question and replaced Q2.

Q1) "LB" is Line Box and it is the junction box I suspected. Further question: do LB have to point down or can they be directed in any direction? Do they have to be a certain distance above the ground?

Q2) Replacement question: For THHN in conduit the 8 AWG will handle 55 AMPS, the spa installation instructions also recommended switching from 6 AWG to 8AWG for a short distance going into the spa. I'm planning on 8 AWG Red, Black, White and Green in the conduit.

Q3) Not going to use unsheathed Romex

Q4) I'll put the disconnect at 48" above the deck.

LB is "el(bow) back" (90 degree ell that turns to the back).

An LR turns right, LL turns keft. They can point in any direction. It's simply a fitting to turn corners with a conduit system.

#8 is good.

Thanks on the LB correction, direction and #8 confirmation.

Just a bunch a work now.

I finished wrestling with the #6, 3 wire in the crawl space. Wish I had started with it on a reel or spool, it got a little out of control. That wire is like a giant spring. Wish I had a video it would have gotten some laughs.

Thanks
Ed