**Assuming U.S. NEC rules: your cable sounds like SER, which cannot be installed underground—even inside conduit. With suitable underground wiring, #2 aluminum generally supports a 90-amp feeder, subject to the conditions below.**

1. **Direct burial or conduit?**

   Check the designation printed on the jacket. Gray 2-2-2-4 cable with three insulated conductors and a bare grounding conductor strongly suggests **Type SER**. NEC 338.12(A)(2) prohibits Type SE cable underground, both directly buried and in conduit. [Southwire’s SER specification](https://www.southwire.com/wire-cable/building-wire/ser-aluminum-service-entrance/p/SPEC10041)

   For the underground portion, use either wet-location-rated conductors, such as XHHW-2, in electrical conduit, or a listed direct-burial wiring assembly. Conductors marked **USE-2/RHH/RHW-2** can cover underground and indoor portions when installed appropriately; USE-only wiring has indoor-use restrictions. Typical cover requirements are **24 inches for direct burial** and **18 inches for PVC conduit**, with exceptions depending on the route and local code. Protect wiring where it emerges from the ground. [Southwire wiring guide](https://www.southwire.com/medias/2405-LV-Cable-Selector-Technical-Reference-Document-Flyer-WEB.pdf), [St. Paul garage-wiring guide](https://www.stpaul.gov/sites/default/files/2023-06/DSI.Bldg_Electrical_Residential%20Garage%20Wiring.pdf)

2. **Maximum feeder breaker?**

   **A 90-amp, two-pole breaker** is the usual maximum for #2 aluminum with **75°C-rated terminals at both ends**, provided no installation conditions require reducing its ampacity. Southwire lists #2 aluminum at 90 amps in the 75°C column. A 90°C insulation marking alone does not authorize using the 100-amp column with 75°C terminals. [Southwire ampacity table](https://www.southwire.com/wire-cable/building-wire/ser-aluminum-service-entrance/p/SPEC10041)

   The special dwelling allowance often associated with “#2 aluminum for 100 amps” generally applies to services and feeders carrying the entire dwelling load. Your garage feeder does not qualify on that basis. Your locally adopted code edition and terminal ratings must be checked before selecting the breaker. [NFPA’s 310.12 text](https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P06_FD_MeetingAgenda_0124.pdf)

3. **How many 15- and 20-amp breakers?**

   There is **no fixed count derived from the feeder amperage**. The panel’s labeling limits the permitted circuits and breaker types; the calculated load determines whether the feeder can supply them. Branch-breaker ratings may total more than 90 amps.

   A 90-amp 120/240-volt feeder supplies up to 90 amps on **each hot leg**. Distribute the 120-volt loads across both legs, and account for continuous loads at 125% in the load calculation. [Schneider Electric feeder-sizing guide](https://productinfo.se.com/0100db2301_elecdistfunddesignguide/viewer?docidentity=LoadPlanning-A48A0BDD&extension=xml&lang=en&manualidentity=DocumentTypeProductCategoryRangeNam-A482E1D1)

For a **detached garage**, also provide a four-wire feeder, separate neutral and ground bars, a bonded grounding bar, a grounding electrode system, and a building disconnect. Ground rods supplement the feeder’s grounding conductor. [St. Paul garage-wiring guide](https://www.stpaul.gov/sites/default/files/2023-06/DSI.Bldg_Electrical_Residential%20Garage%20Wiring.pdf)

**Your proposed underground setup needs different wiring if the jacket says SER.** Verify the full jacket markings and have the local inspector or electrician confirm the wiring method, load calculation, and service capacity before installation.