I agree that this discussion has no doubt gotten far more complex than what they originally intended but you cannot blame me. If all they originally wanted was a hose bid near the garage I would have began by suggesting a lawn hydrant, however the original post was a bit more complex than that: Quote from the original post:- "I will be installing a slop sink, house bib and possibly a small water heater to start. Might also add a half bath in the future" I am merely pointing out that if they intend to install a sink or perhaps a half bath in future the code requires an approved drainage system as a pre-requisite to install any fixtures inside the structure. Taking this to the next level, we have no yet even begun to discuss the problems of installing fixtures I an unheated structure in a cold climate. If you were asking my personal opinion I would say the whole idea will soon prove to be cost prohibitive. NOW FOR THE NEXT QUESTION: "What is the rationale for requiring a separate sewer tie-in for outbuildings? ANSWER: All of the DWV (Drain, Waste & Vent) lines inside a structure eventually combine into one line before passing through the footer wall to exit the structure. That single line is properly defined as the house or building "Main Drain". Code requires that we must install a "Main cleanout" on that line within 3 of the footer wall. For structures built over a basement the main cleanout is generally installed immediately inside the footer wall in the basement. For structures on slab it is generally located outside the structure within 3 of the footer wall. For structures on a raised foundation with a crawlspace the cleanout may be inside or outside the structure. The main cleanout officially designates the end of the "Main Drain" and the beginning of the "house or building Sewer". On a residential property the "House Sewer" is generally consider the primary sewer line for the property and it would discharge directly into a "Municipal Sewer" or a "Septic Tank. Code only allows one line to connect to the municipal sewer or the septic tank, therefore when we have additional outbuildings that are equipped with plumbing fixtures the "building sewer" from the outbuildings must tie into the "House Sewer" before tying into the municipal sewer or septic tank. It must also be mentioned here that all DWV and Sewer Lines are sized by the DFU (Drainage Fixture Unit) load calculation method. The code gives us a list of all the fixtures that may be connected to a drainage system in both residential and commercial plumbing systems. The list then gives us a minimum size of drain opening or pipe and the DFU load value for each fixture. (IRC table 3004.1 & table 3201.7) Example: Lavatory 1-1/4" pipe & 1DFU, shower/tub 1-1/2 pipe and 2DFU, Shower stall 2" pipe and 2DFU, watercloset with 1.6gpf or less flush min. 3" pipe and 3DFU. A watercloset with greater than 1.6gpf = 3" line and 4DFU, kitchen sink 1-1/2" pipe and 2DFU, A Baptismal pool in your church is a 2"line and 3DFU while an office water cooler is 1-1/4" line and 1DFU and an Autopsy table at your local coroners office is a 2" line and 3DFUs. The code then gives us another table that lists the maximum number of DFUs that may be conveyed by each size of pipe. (IRC table 3005.4.1) Example: For the DWV lines within a structure the table lists the following 1-1/4" =1DFU 1-1/2"=3DFU 2"=6DFU 3"=20DFU 4"=160DFU When designing a DWV system we must begin at each fixture and attach the code required size of drain line then at every junction where two or more pipes combine we must compute the total DFU load at that point and select the appropriate size of pipe from that point onward. When we have more than one structure equipped with plumbing on a building lot we must do basically the same thing. We begin by calculating the total DFU load for each structure. At every point where two or more building sewers combine we must add the DFU load for each structure to determine the total combined load on the sewer line at the junction then we consult another table that defines the maximum number of DFUs permitted on each size of pipe. Example from IRC table3005.4.2 3" with ¼"/ft pitch 42DFU 4" with ¼"/ft pitch 216DFU 3" with 1/8"/ft pitch 36DFU 4" with 1/8"/ft pitch 180DFU (The IRC permits a 3" line to run with a 1/8"/ft pitch only with the expressed written consent of the local authority having jurisdiction)

He is 100% INCORRECT. NO grounding electrode and NO water bond! A 4-wire feeder is all that is required or wanted. A 3-wire feeder in a complete metallic conduit system works as well, but the fittings must be made up tight and the bonding on both ends must be correct.

I believe this three wire system was to code a few years ago for detached structures.The cable had been connected to an older panel,but was removed when it was decided to convert the garage into a workshop.A newer sub panel was mounted on the wall with a 70 amp double pole breaker and the same size was installed at the main panel.The previous installation seemed to function quite well,but it was hard to find breakers when I wanted to ad to the panel.The cable looks to have 2 #4 insulated aluminum wires with a similar bare ground.The 2 hot wires were connected to the breaker,and I think,but not sure that the ground wire was attached to the common bus bar with the bonding strap removed.All the equipment white wires were attached to the common bus and all the equipment grounds went to the ground bus which was attached to the panel box and to the grounding rod outside the building.Hoping this helps and thanks for any feedback you have.

The orange stuff is NM cable... NEC 300.5 (B). Wet Locations. The interior of enclosures or raceways installed underground shall be considered to be a wet location. Insulated conductors and cables installed in these en-closures or raceways in underground installations shall be listed for use in wet locations and shall comply with 310.8(C). Any connections or splices in an in wet locations and shall comply with 310.8(C). Any connections or splices in an underground installation shall be approved for wet locations. 300.9 Raceways in Wet Locations Above Grade.Where raceways are installed in wet locations abovegrade, the interior of these raceways shall be considered to be a wet location. Insulated conductors and cables installed in raceways in wet locations abovegrade shall comply with 310.8(C). 310.8 (C) Wet Locations. Insulated conductors and cables used in wet locations shall comply with one of the following: (1) Be moisture-impervious metal-sheathed (2) Be types MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, ZW (3) Be of a type listed for use in wet locations. 334.12 Uses Not Permitted (B) Types NM and NMS. Types NM and NMS cables shall not be used under the following conditions or in the following locations: (1) Where exposed to corrosive fumes or vapors (2) Where embedded in masonry, concrete, adobe, fill, or plaster (3) In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish (4) In wet or damp locations.