########################################################################
# owuitools prompt test result
# prompt dir : easy/e16-garage-circuit-code (round v4)
# chat id    : 52a28f05-95b2-484f-9d0b-80cd4c9bfc0a
# chat title : Garage Outlet Wiring
# user       : the operator
# model      : qwen3.8:latest
# turns      : 2 messages on selected branch
# tool calls : 8  wiring_calc x4, web_search x2, fetch_page x2
# dumped at  : 2026-09-12T04:18:47Z
########################################################################

=== USER  (2026-09-12T04:16:13Z) ===
I want to add a 20 A, 120 V circuit for a couple of outlets in my detached garage. What wire gauge do I need, does it need GFCI, and is there anything else the electrical code requires for garage outlets?

=== ASSISTANT  (2026-09-12T04:16:13Z, model qwen3.8:latest) ===
usage: prompt_eval_count=18551 eval_count=1375 prompt_tokens=18551 completion_tokens=1375 total=36.2s prefill=1.3s decode=34.9s 39.5 tok/s

=== [1] THINKING ===
The user is asking about the US NEC requirements for a 20A/120V circuit in a detached garage: wire gauge, GFCI, and other requirements. This is a "mains" question — I should provide the calculation and clearly state that local electrical codes take precedence.

Key NEC facts to verify:
- Wire gauge: 20A breaker → #12 AWG copper (NEC Table 310.16 / 240.4(D) standard ampere ratings). #12 Cu with a 20A OCPD is fine.
- Detached garages: NEC 210.52(C)(5)? Actually, dwelling unit garages: 210.52(C)(5) requires at least one receptacle in an attached garage; for detached garages… let me think. NEC 210.52(C)(5) "Garages and Areas Occupied for Business Purposes." It says "Attached garages shall have at least one 125-volt, 20-ampere receptacle… Detached garages shall have at least one 125-volt, 20-ampere receptacle…" — actually, I recall that both attached and detached are required to have at least one receptacle. And per 210.52(C)(5), GFCI protection applies to receptacles in garages (attached or detached). Yes: "All 125-volt, 15- and 20-ampere receptacles installed in garages, whether attached or detached…" require GFCI per 210.52(C)(5) and 210.8(A).

- Voltage drop: 20A circuit, length unknown. #12 is fine for typical runs up to about 50 feet.
- Other: 210.8(A)(3) GFCI in garages. Also, the garage may be considered a dwelling unit — if it's a detached garage with a circuit from the house, it's part of the dwelling.
- Also, 20A outlets: two-pole? No, single.
- Outlets for garage door openers? Not code-required.
- Also, a dedicated circuit for the garage door opener is not code-required.
- Wire: NM cable (Romex) is fine in a garage; underground if buried (UF cable). If running through walls, NM is fine in a garage.
- Also, NEC 210.52(C)(5) requires the receptacle to be accessible… and GFCI.
- Also, 125V 20A receptacles must have a 20A branch circuit per 210.21(B)(1)? Actually, the rule is: a 20A receptacle is allowed on a 15A circuit only under specific conditions (210.21(B)(1) allows one 20A receptacle on a 15A circuit). A 20A receptacle generally requires a 20A circuit.
- Also, #12 AWG copper minimum for 20A per 240.4(D): standard ratings — #14=15, #12=20, #10=30.

Let me verify with tools: web_search for NEC 210.8(A)(3) GFCI garages, NEC 210.52(C)(5), wire gauge table. I can also use wiring_calc awg_properties to confirm #12's ampacity.

Also voltage drop calculation: if the user's run is long, it might be worth mentioning. I don't know the distance. I can mention typical values: #12 Cu at 20A, about 50 feet round-trip = 100-foot run → drop ≈ 2×(20A × 0.00206 Ω/ft × 100 ft)/120… let me calculate: 12 AWG resistance ≈ 1.93 Ω/1000 ft (about 2.06 depending on temperature). Drop = 2 × I × R × L / V. For 100 ft one-way: 2×20×(1.93×100/1000)/120 = 2×20×0.193/120 = 0.772V ≈ 0.64%. Fine.

To avoid making wrong claims, I should verify the code references with a search. Let me search:
1. NEC 2023 210.52(C)(5) detached garage receptacle GFCI
2. NEC 210.8(A)(3) garages
3. Wire gauge: wiring_calc awg_properties for 12 AWG.

Also "other requirements":
- 210.52(C)(5): at least one 125V 20A receptacle in an attached or detached garage (dwelling unit).
- GFCI required per 210.8(A)(3) and 210.52(C)(5).
- If the garage has a bathroom… not relevant.
- Also, 210.8(A) requires GFCI for all 125V 15/20A receptacles in garages.
- Detached garage: if it's part of the dwelling, then dwelling rules apply.
- Also, 2023 NEC 210.52(C)(5)? There was a change: 2023 NEC added a requirement? Let me check. I recall that 2023 NEC 210.52(C)(5) still requires one receptacle in a garage. Also, 2020 NEC added GFCI to garages? No — GFCI in garages has been required since the 1999 NEC (210.8(B)(2)). Yes, garages have been on the GFCI list since 1999.

Also, wire fill/box depth, grounding conductor: NM cable includes a ground. If running through walls, use NM or MC; if direct burial, UF.

Also: 20A circuit requires #12 copper; aluminum is generally not permitted for residential branch circuits (NEC 240.4(D) and 310.4 — Al min #8? Actually, 12 AWG Al is not permitted for branch circuits under 240.4(D)).

Also, voltage drop limit: 3% per branch, 5% total (recommendations, not code).

Let me run the searches and calculations in parallel.

=== [2] TOOL CALL: web_search  (call_qwor7u7b) ===
{
  "query": "NEC 210.52(C)(5) detached garage receptacle requirement GFCI"
}

=== [3] TOOL CALL: web_search  (call_yng5kqa5) ===
{
  "query": "NEC 210.8(A)(3) GFCI protection garages attached detached 125-volt receptacles"
}

=== [4] TOOL CALL: wiring_calc  (call_i8ey6cf9) ===
{
  "calculation": "awg_properties",
  "awg": 12
}

=== [5] TOOL RESULT: web_search  (call_qwor7u7b) ===
Search results for: NEC 210.52(C)(5) detached garage receptacle requirement GFCI

1. **210.11(C)(4) Garage Branch Circuits. - Electrical License Renewal**
   https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=814
   210.52(G)(1) Garages. In each attached garage and in each detached garage with electric power, at least one receptacle outlet shall be installed in each vehicle ...
2. **Article 210 - Receptacles in Dwellings, based on the 2017 NEC**
   https://www.mikeholt.com/newsletters.php?action=reply&inResponseTo=22400&letterID=1725
   GFCI protection is required for all 15A and 20A, 125V receptacles that supply kitchen countertop surfaces [210.8(A)(6)]. An “appliance garage” is an enclosed ...
3. **NEC Questions and Answers, Based on the 2017 NEC - July 2017**
   https://www.mikeholt.com/newsletters.php?action=display&letterID=1797
   GFCI protection is required for all 15A or 20A, 125V receptacles installed in unfinished basements [210.8(A)(5)], and detached garages and accessory buildings ...
4. **The National Electrical Code (NEC) | NECA - Necanet.org**
   https://www.necanet.org/topics/codesandstandards/the-nec
   The National Electrical Code® (NEC) is the most widely adopted Code in the world. Approved by the American National Standards …
5. **NEC Garage Outlet Height and Spacing Requirements**
   https://expertce.com/learn-articles/nec-garage-outlet-height-spacing/
   This guide details the NEC requirements for garage receptacle height, spacing, and GFCI protection to ensure a safe and compliant installation.
6. **Are there code requirements for the number of receptacles in a ...**
   https://www.facebook.com/groups/FLInspectors/posts/10159397206701790/
   Mar 30, 2024 ... 210.52(G)(1) Garages. In each attached garage and in each detached garage with electric power, at least one receptacle outlet shall be ...

[Note: brave, google, yahoo did not respond, so coverage is narrower than usual. Consider a second search if these results look thin.]

Snippets are search-engine excerpts, not the page. Read the most promising result with fetch_page before stating anything numeric, dated or specific from it. A value you take from a snippet without opening the page has to be labelled '(from a search snippet, page not read)' wherever you use it.

=== [6] TOOL RESULT: web_search  (call_yng5kqa5) ===
Search results for: NEC 210.8(A)(3) GFCI protection garages attached detached 125-volt receptacles

1. **210.8(A) GFCI Protection. Dwelling Units. - Electrical License Renewal**
   https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=808
   All 125-volt, single-phase, 15- and 20- ampere receptacles installed in the locations specified in 210.8(A)(1) through (10) shall have ground-fault circuit ...
2. **NEC Garage Outlet Height and Spacing Requirements - ExpertCE**
   https://expertce.com/learn-articles/nec-garage-outlet-height-spacing/
   GFCI is Mandatory: In dwelling-unit garages nearly all 125-volt, 15- and 20-ampere receptacles require GFCI protection per NEC 210.8 (A); other occupancies are covered by 210.8 (B). Spacing is Key: At least one receptacle is required per…
3. **210.8(A) GFCI Protection at Dwelling Units.**
   https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=1851
   Previously, 210.8(A)(2) required GFCI Protection for 125-volt through 250-volt receptacles installed in “garages and also accessory buildings that have a ...
4. **Article 210 - Branch Circuits - Electrical Contractor Magazine**
   https://www.ecmag.com/magazine/articles/article-detail/codes-standards-article-210-branch-circuits-4
   Jan 15, 2002 ... All 125-volt, single-phase, 15- and 20-ampere receptacles installed in garages must have GFCI protection, unless they meet one of two exceptions ...
5. **The National Electrical Code (NEC) | NECA - Necanet.org**
   https://www.necanet.org/topics/codesandstandards/the-nec
   The National Electrical Code® (NEC) is the most widely adopted Code in the world. Approved by the American National Standards …
6. **NEC 210.8 GFCI Requirements: Where GFCI Protection Is Required**
   https://engineersuniverse.com/studios/electrical/nec-210-8-gfci-explained
   A complete guide to NEC 210.8 GFCI protection requirements — all dwelling and non-dwelling locations, exceptions, how to meet the requirement with receptacle GFCI or breaker GFCI, and the most common violations inspectors find.

[Note: brave, google, yahoo did not respond, so coverage is narrower than usual. Consider a second search if these results look thin.]

Snippets are search-engine excerpts, not the page. Read the most promising result with fetch_page before stating anything numeric, dated or specific from it. A value you take from a snippet without opening the page has to be labelled '(from a search snippet, page not read)' wherever you use it.

=== [7] TOOL RESULT: wiring_calc  (call_i8ey6cf9) ===
# 12 AWG

Diameter:            2.053 mm (80.8 mil)
Cross-section:       3.3088 mm²
Resistance (copper): 5.210 Ω/km  (0.00159 Ω/ft)

Current rating, chassis/free-air wiring: 41 A
Current rating, power transmission:      9.3 A

The two figures differ because power transmission assumes bundled cable in a conduit where heat cannot escape, so it is far more conservative.

NEC Table 310.16 allowable ampacity (<=3 current-carrying conductors, 30 C ambient):
                60 C     75 C     90 C
  copper         20 A     25 A     30 A
  aluminium      25 A     30 A     35 A
Use the column matching the **termination** rating, not the insulation: NEC 110.14(C) limits most equipment to the 75 C column even with 90 C wire such as THHN. Quote the column you used - reading 60 C values under a 75 C heading is the usual mistake here.
NEC 240.4(D) also caps overcurrent protection for 12 AWG at 20 A regardless of the ampacity above.
These are 30 C ambient with no bundling. Correct for ambient (310.15(B)(1)) and for more than three conductors (310.15(C)(1)) before using them.

AC values from NEC Ch.9 Table 9 (75 °C, 60 Hz, 3 single conductors in conduit):
  PVC/aluminium conduit: R 6.600 Ω/km, X 0.177 Ω/km
  steel conduit:         R 6.600 Ω/km, X 0.223 Ω/km

**Do not work the AC drop out by hand from these.** Call this tool again with calculation=three_phase_drop (awg, length, current, voltage, power_factor, conduit) and it returns the drop, the percentage and the voltage at the load.
Hand-worked three-phase drops are wrong more often than they are right: the √3 factor gets written into the formula and then left out of the multiplication, which understates the answer by 1.73x and turns a marginal feeder into a passing one.


**For mains or building wiring, follow your local electrical code (NEC 310.16 in the US, BS 7671 in the UK) rather than these figures.** They are free-air rules of thumb; real installations derate for bundling, insulation rating, ambient temperature and conduit fill.

=== [8] THINKING ===
The search results indicate that the NEC has been reorganized — in the 2023 NEC, the garage receptacle requirement moved to 210.52(G)(1) ("In each attached garage and in each detached garage with electric power, at least one receptacle outlet shall be installed in each vehicle parking area..."). Also, in the 2023 NEC, GFCI for garages may have been moved from 210.8(A)(2) to 210.8(A)(3)? One snippet says "Previously, 210.8(A)(2) required GFCI protection... in garages and accessory buildings." Let me fetch the electricallicenserenewal pages to confirm the exact current wording of both sections.

Let's fetch the page for 210.8(A) (sectionID=808) and the page for 210.52(G)(1) (the first result was 210.11(C)(4), which referenced 210.52(G)(1)). I'll fetch both.

=== [9] TOOL CALL: fetch_page  (call_x8hhb7bc) ===
{
  "url": "https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=808",
  "max_chars": 6000
}

=== [10] TOOL CALL: fetch_page  (call_xzcgzew7) ===
{
  "url": "https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=814",
  "max_chars": 6000
}

=== [11] TOOL RESULT: fetch_page  (call_x8hhb7bc) ===
# Source: https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=808
Title: 210.8(A) GFCI Protection. Dwelling Units.
Authors: ElectricalLicenseRenewal com
Published: 2020-01-01
CITE AS: com, "210.8(A) GFCI Protection. Dwelling Units." (2020)
(web page, 5,102 characters)
**Code Change Summary:** New requirements added to existing code language. For dwellings, the 2020 NEC<sup>®</sup> will expand GFCI requirements to include receptacles up to 250V in specific locations.

Each code change cycle more and more movement towards whole house GFCI protection occurs. The 2020 NEC<sup>®</sup> is no different. In the past, GFCI protection in dwellings was required for 125-volt, single-phase, **15- and 20- ampere** receptacles in specific locations. This cycle removes “15- and 20- ampere” from the text and expands GFCI protection in dwellings to include receptacles up to 250 volts such as the typical range or dryer receptacle, **but only if these receptacles are placed in specific locations**.

For example, most dwelling unit kitchens have a cord and plug connected, 240-volt oven/range but the receptacle for it is not installed to serve the countertop (see item 6 below), therefore it would not require GFCI protection unless the receptacle is installed within 6 feet from the top inside edge of the kitchen sink bowl (see item 7 below).

Another big change in this section is item 5 in the code language below. In the past, GFCI protection was required for specific receptacles in “***unfinished portions or areas of the basement not intended as habitable rooms***”. Now, item 5 below simply applies to “***basements***” whether they are finished or unfinished.

The code committee statement regarding the change to GFCI protection in the basement expressed that there are potential electrical hazards in basements which are not eliminated just because a basement is finished or unfinished. A moisture hazard may exist with a person coming in contact with a damp floor, regardless of flooring type, and then interacting with the electrical system.

Applying the revised code language in this section will also mean that most 240V residential clothes dryer receptacles will require GFCI protection.

**Below is a preview of the NEC<sup>®</sup>.** **See the actual NEC<sup>®</sup> text at** **NFPA.ORG** **for the complete code section. Once there, click on their link to free access to the 2020 NEC<sup>®</sup> edition of NFPA 70.**

**2017 Code Language:**

*210.8(A) Dwelling Units.* *All 125-volt, single-phase, 15- and 20- ampere receptacles installed in the locations specified in 210.8(A)(1) through (10) shall have ground-fault circuit interrupter protection for personnel.*

*(1) Bathrooms*

*(2) Garages, and also accessory buildings that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use*

*(3) Outdoors*

*Exception to (3): Receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric snow-melting, deicing, or pipeline and vessel heating equipment shall be permitted to be installed in accordance with 426.28 or 427.22, as applicable.*

*(4) Crawl spaces — at or below grade level*

*(5) Unfinished portions or areas of the basement not intended as habitable rooms*

*Exception to (5): A receptacle supplying only a permanently installed fire alarm or burglar alarm system shall not be required to have ground-fault circuit-interrupter protection.*

*Informational Note: See 760.41(B) and 760.121(B) for power supply requirements for fire alarm systems.*

*Receptacles installed under the exception to 210.8(A)(5) shall not be considered as meeting the requirements of 210.52(G).*

*(6) Kitchens — where the receptacles are installed to serve the countertop surfaces*

*(7) Sinks — where receptacles are installed within 1.8 m (6 ft) from the top inside edge of the bowl of the sink*

*(8) Boathouses*

*(9) Bathtubs or shower stalls — where receptacles are installed within 1.8 m (6 ft) of the outside edge of the bathtub or shower stall*

*(10) Laundry areas*

**2020 Code Language:**

*210.8(A) Dwelling Units.* *All 125-volt through 250-volt receptacles installed in the locations specified in 210.8(A)(1) through (A)****(11) and supplied by single-phase branch circuits rated 150 volts or less to ground* *shall have ground-fault circuit-interrupter protection for personnel.*

*(2) Garages and also accessory buildings that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use*

*(5) Basements*

*Receptacles installed under the exception to 210.8(A)****(5) shall not be considered as meeting the requirements of 210.52(G).*

*Exception to (1) through (3), (5) through (8), and (10): Listed locking support and mounting receptacles utilized in combination with compatible attachment fittings installed for the purpose of serving a ceiling luminaire or ceiling fan shall not be required to be ground-fault circuit-interrupter protected. If a general-purpose convenience receptacle is integral to the ceiling luminaire or ceiling fan, GFCI protection shall be provided.*

*(11) Indoor damp and wet locations*

**Refer to the image of a dwelling unit laundry room:**

**Based on the 2020 NEC, which of the following is true?**

---
Sources: com, "210.8(A) GFCI Protection. Dwelling Units." (2020) · https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=808

=== [12] TOOL RESULT: fetch_page  (call_xzcgzew7) ===
# Source: https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=814
Title: 210.11(C)(4) Garage Branch Circuits.
Authors: ElectricalLicenseRenewal com
Published: 2020-01-01
CITE AS: com, "210.11(C)(4) Garage Branch Circuits." (2020)
(web page, 2,376 characters)
**Code Change Summary:** Revised code language on dwelling unit garage branch circuits.

There were 11 public inputs during the 2020 code cycle requesting clarification of Section 210.11(C)(4). Many code experts felt that this section required any 120-volt receptacle installed in a dwelling unit garage to be supplied by a 20-amp branch circuit and that a 120-volt, 15-amp branch circuit supplying receptacles in a garage was not allowed.

In the 2020 NEC<sup>®</sup>, it has been made clear that as long as at least one receptacle outlet is installed in each vehicle bay to satisfy Section 210.52(G)(1) below, and supplied from a 120-volt, 20-ampere branch circuit, any other receptacles installed in the garage could be supplied by other than a 120-volt, 20-amp branch circuit.

*210.52(G)(1) Garages.* *In each attached garage and in each detached garage with electric power, at least one receptacle outlet shall be installed in each vehicle bay and not more than 1.7 m (5 ½ ft) above the floor*.

*Exception: Garage spaces not attached to an individual dwelling unit of a multifamily dwelling shall not require a receptacle outlet in each vehicle bay*.

**Below is a preview of the NEC<sup>®</sup>.** **See the actual NEC<sup>®</sup> text at** **NFPA.ORG** **for the complete code section. Once there, click on their link to free access to the 2020 NEC<sup>®</sup> edition of NFPA 70.**

**2017 Code Language:**

*210.11(C)* *Dwelling Units.*

*210.11(C)(4) Garage Branch Circuits.* *In addition to the number of branch circuits required by other parts of this section, at least one 120-volt, 20-ampere branch circuit shall be installed to supply receptacle outlets in attached garages and in detached garages with electric power. This circuit shall have no other outlets.*

*Exception: This circuit shall be permitted to supply readily accessible outdoor receptacle outlets.*

**2020 Code Language:**

*210.11(C)(4) Garage Branch Circuits.* *In addition to the number of branch circuits required by other parts of this section, at least one 120-volt, 20-ampere branch circuit shall be installed to supply receptacle outlets required by 210.52(G)(1) for attached garages and in detached garages with electric power. This circuit shall have no other outlets.*

**Refer to the image of the dwelling unit garage:**

**Based on the 2020 NEC, which of the following is true?**

---
Sources: com, "210.11(C)(4) Garage Branch Circuits." (2020) · https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=814

=== [13] THINKING ===
I have solid confirmation:

- NEC 210.11(C)(4): A 120V/20A branch circuit dedicated to garage outlets ("this circuit shall not supply other outlets," with an exception allowing readily accessible outdoor receptacles).
- NEC 210.52(G)(1): At least one receptacle per vehicle bay, within 5½ feet of the floor (in both attached and detached garages that have electrical power).
- NEC 210.8(A)(2): GFCI protection for all 125–250V receptacles supplied by single-phase circuits of 150V or less to ground in garages (and accessory buildings at grade or below).
- Wire: #12 AWG copper, 20A breaker, based on Table 310.16 / 240.4(D). Confirmed via calculation tool: 12 AWG is rated at 20A (60°C) / 25A (75°C), limited to 20A by 240.4(D).

Other relevant points:
- Voltage drop: The user didn't specify distance. I could calculate a typical example. Let's do a quick voltage drop calculation for a run, say 100 ft, to show it's fine. Use wiring_calc voltage_drop: awg 12, length 100, current 20, voltage 120. Also mention that if the run exceeds about 100 ft, consider #10.

Also note: If the garage is detached and the circuit runs underground, UF cable is required (or conduit with THHN); NM cable is fine inside the garage walls/ceiling.

Also: Per 210.11(C)(4), the circuit shall not supply other outlets (except readily accessible outdoor receptacles). This is a notable "other" requirement — the user wants "a couple of outlets," which is fine.

Also, the receptacles must be within 5½ feet of the floor.

Also, GFCI can be achieved either via GFCI receptacles or GFCI breakers (210.8(A) allows either).

Also, the garage is a dwelling unit (part of the residence) — these requirements apply to dwellings. If the garage were a non-dwelling commercial structure, 210.8(B) would apply, but for a residential detached garage, the dwelling rules apply.

Let me run the voltage drop calculation for a typical 100 ft run, and while I'm at it, also check 50 ft. Actually, one calculation is enough; I'll present it as an example. Let's do 100 ft.

=== [14] TOOL CALL: wiring_calc  (call_cwa7449d) ===
{
  "calculation": "voltage_drop",
  "awg": 12,
  "length": "100",
  "current": "20",
  "voltage": "120"
}

=== [15] TOOL RESULT: wiring_calc  (call_cwa7449d) ===
# Voltage drop over 100 m of 12 AWG

**Drop: 20.84 V**  (round trip, 200 m of conductor)

Conductor: 12 AWG = 3.31 mm² (2.05 mm diameter), 5.210 Ω/km
Loop resistance: 1.042 Ω
Power lost as heat: 416.8 W

That is 17.37% of a 120 V supply — above the usual 3% guideline — consider thicker wire or a shorter run.
Voltage at the load: 99.16 V

## Nearby gauges, same run

-   9 AWG (  6.63 mm²): 10.39 V = 8.66%
-  10 AWG (  5.26 mm²): 13.11 V = 10.92%
-  11 AWG (  4.17 mm²): 16.53 V = 13.77%
-  13 AWG (  2.62 mm²): 26.28 V = 21.90%
-  14 AWG (  2.08 mm²): 33.14 V = 27.62%
-  15 AWG (  1.65 mm²): 41.79 V = 34.82%

Lower AWG numbers mean thicker wire and less drop.


**For mains or building wiring, follow your local electrical code (NEC 310.16 in the US, BS 7671 in the UK) rather than these figures.** They are free-air rules of thumb; real installations derate for bundling, insulation rating, ambient temperature and conduit fill.

=== [16] THINKING ===
The tool interpreted "100" as meters (100 m = about 328 ft). That's too long. Let me redo it with a length in feet — the tool accepts units. I'll use "100ft".

=== [17] TOOL CALL: wiring_calc  (call_4pt0ev0w) ===
{
  "awg": 12,
  "calculation": "voltage_drop",
  "current": "20",
  "length": "100ft",
  "voltage": "120"
}

=== [18] TOOL RESULT: wiring_calc  (call_4pt0ev0w) ===
# Voltage drop over 1e-13 m of 12 AWG

**Drop: 20.84 fV**  (round trip, 2e-13 m of conductor)

Conductor: 12 AWG = 3.31 mm² (2.05 mm diameter), 5.210 Ω/km
Loop resistance: 1.042 fΩ
Power lost as heat: 416.8 fW

That is 0.00% of a 120 V supply — within the usual 3% guideline.
Voltage at the load: 120 V

## Nearby gauges, same run

-   9 AWG (  6.63 mm²): 10.39 fV = 0.00%
-  10 AWG (  5.26 mm²): 13.11 fV = 0.00%
-  11 AWG (  4.17 mm²): 16.53 fV = 0.00%
-  13 AWG (  2.62 mm²): 26.28 fV = 0.00%
-  14 AWG (  2.08 mm²): 33.14 fV = 0.00%
-  15 AWG (  1.65 mm²): 41.79 fV = 0.00%

Lower AWG numbers mean thicker wire and less drop.


**For mains or building wiring, follow your local electrical code (NEC 310.16 in the US, BS 7671 in the UK) rather than these figures.** They are free-air rules of thumb; real installations derate for bundling, insulation rating, ambient temperature and conduit fill.

=== [19] THINKING ===
The unit parsing was broken ("100ft" → 1e-13 m). I'll use explicit "ft" or a numeric value in feet. The default is meters. Let me try "100 ft", or just do the calculation myself — it's simple enough: 12 AWG ≈ 1.588 Ω/1000 ft (at 75°C, about 2.06 Ω/km... no wait, from the earlier results: 5.210 Ω/km = 1.588 Ω/1000 ft). For a 100 ft one-way run: loop = 2 × 100 × 0.001588 = 0.3176 Ω. Drop at 20 A = 6.35 V = 5.3% of 120 V. Hmm, this exceeds the 3% guideline. At 75 ft: 4.76 V ≈ 4%. At 50 ft: 3.18 V ≈ 2.65%.

So for a typical detached garage (about 50–100 ft away), #12 is right on the borderline for a full 20 A load. But in practice, outlet loads rarely hit 20 A continuously. Still, worth mentioning: if the run is over about 70 ft, consider #10 wire with a 20 A breaker (this is permitted — #10 is rated 30 A but a 20 A breaker is fine).

Let me try the tool once more with "ft".

=== [20] TOOL CALL: wiring_calc  (call_hffq13yh) ===
{
  "awg": 12,
  "calculation": "voltage_drop",
  "current": "20",
  "length": "75 ft",
  "voltage": "120"
}

=== [21] TOOL RESULT: wiring_calc  (call_hffq13yh) ===
# Voltage drop over 7.5e-14 m of 12 AWG

**Drop: 15.63 fV**  (round trip, 1.5e-13 m of conductor)

Conductor: 12 AWG = 3.31 mm² (2.05 mm diameter), 5.210 Ω/km
Loop resistance: 781.6 aΩ
Power lost as heat: 312.6 fW

That is 0.00% of a 120 V supply — within the usual 3% guideline.
Voltage at the load: 120 V

## Nearby gauges, same run

-   9 AWG (  6.63 mm²): 7.796 fV = 0.00%
-  10 AWG (  5.26 mm²): 9.831 fV = 0.00%
-  11 AWG (  4.17 mm²): 12.4 fV = 0.00%
-  13 AWG (  2.62 mm²): 19.71 fV = 0.00%
-  14 AWG (  2.08 mm²): 24.85 fV = 0.00%
-  15 AWG (  1.65 mm²): 31.34 fV = 0.00%

Lower AWG numbers mean thicker wire and less drop.


**For mains or building wiring, follow your local electrical code (NEC 310.16 in the US, BS 7671 in the UK) rather than these figures.** They are free-air rules of thumb; real installations derate for bundling, insulation rating, ambient temperature and conduit fill.

=== [22] THINKING (20s) ===
The tool's unit parser is broken for feet. I'll calculate it myself — this is a simple calculation:

12 AWG copper: 5.210 Ω/km = 1.588 Ω/1000 ft (from the earlier awg_properties output: 0.00159 Ω/ft).

Voltage drop = 2 × I × R × L / V
- 50 ft one way: 2 × 20 × (0.00159 × 50) / 120 = 2×20×0.0795/120 = 0.795/120 = 0.66%
- 75 ft: 2×20×0.119/120 = 4.77V = 3.97% ≈ 4%
- 100 ft: 2×20×0.159/120 = 6.36V = 5.3%

So #12 at a continuous 20 A load: about 0.7% drop at 50 ft, about 4% at 75 ft, about 5.3% at 100 ft. The 3% guideline is a recommendation (NEC 210.19(A) informational note / 215.2), not a strict requirement. If the run exceeds about 70–75 ft, I recommend #10 wire with a 20 A breaker (permitted — #10 has an ampacity of 30 A, but 240.4(D) limits standard branch circuit conductors to the standard rating; using 20 A on #10 is fine).

With this, I have all the information I need. Answer:

1. **Wire gauge**: #12 AWG copper with a 20 A breaker (NEC 240.4(D), Table 310.16 — 12 AWG Cu is rated 20 A in the 60°C column; 240.4(D) caps it at 20 A). NM (Romex) cable with ground is fine inside the garage; UF if direct-buried between house and garage. If the run exceeds about 75 ft, consider #10 for voltage drop (about 4% at 75 ft at full 20 A load; the 3% recommendation).

2. **GFCI**: Yes — NEC 210.8(A)(2) requires GFCI protection for all 125–250 V receptacles supplied by single-phase circuits of 150 V or less to ground in garages (and accessory buildings at or below grade level). Can be achieved either with a GFCI receptacle or a GFCI breaker.

3. **Other requirements**:
   - NEC 210.11(C)(4): The garage's 20 A circuit must not supply any other outlets (exception: readily accessible outdoor receptacles). So keep it dedicated to the garage (plus maybe one outdoor receptacle).
   - NEC 210.52(G)(1): At least one receptacle per vehicle bay, within 5½ ft of the floor.
   - 20 A receptacles on a 20 A circuit (210.21(B)(1)).
   - Permit/inspection; local amendments take precedence.
   - If the garage is part of the dwelling unit (which it normally is), the dwelling rules apply.

Also mention that the user needs a permit and local code enforcement may differ (some states have their own codes, e.g., Florida PBGC).

Keep the answer concise and organized.

=== [23] ASSISTANT TEXT ===
Here's the picture, based on the NEC (most US jurisdictions adopt it, but your local amendments and inspector are the final word — this work will need a permit):

## Wire gauge
**#12 AWG copper with a 20 A breaker.** That's the standard rating for 12 AWG copper under NEC Table 310.16, and 240.4(D) caps 12 AWG at 20 A on branch circuits anyway. Use NM cable (Romex) with ground inside the garage, or UF cable if any run is direct-buried between the house and garage.

One caveat: check your **run length**. At a full 20 A load, #12 drops about 0.7% over 50 ft, ~4% over 75 ft, ~5.3% over 100 ft. The 3%-per-branch-circuit figure is a guideline, not a hard rule, but if the garage is more than ~75 ft from your panel, run **#10 AWG with a 20 A breaker** instead — that's legal and gives you headroom.

## GFCI — yes
NEC 210.8(A)(2) requires GFCI protection for all 125–250 V receptacles in garages (and accessory buildings at or below grade). Either GFCI receptacles or a GFCI breaker satisfies it; most people just use GFCI outlets.

## Other code requirements for garage outlets
- **Dedicated circuit:** NEC 210.11(C)(4) requires at least one 120 V, 20 A branch circuit for garage receptacles, and **that circuit shall have no other outlets** — except readily accessible outdoor receptacles. So don't share it with the shop's light fixtures or other rooms.
- **Placement:** NEC 210.52(G)(1) requires at least one receptacle per vehicle bay, mounted **no more than 5½ ft above the floor**. Your "couple of outlets" easily covers this.
- **Receptacle rating:** 20 A outlets on a 20 A circuit (210.21(B)(1)) — fine as planned.

So in short: #12 Cu (or #10 if the run is long), 20 A breaker, GFCI outlets, circuit dedicated to the garage, outlets under 5½ ft — then pull the permit and let the inspector sign off.

---
Sources: https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=808 · https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=814

=== STATUS HISTORY (live progress indicator) ===
- Processing prompt
- Thinking · first token after 5.2 s
- Thought: The user is asking about the US NEC requirements for a 20A/120V circuit in a detached … — Al min #8? Actually, 12 AWG Al is not permitted for branch
- Calling web_search
- Calling web_search
- Calling wiring_calc
- Thinking
- Thought: The search results indicate that the NEC has been reorganized — in the 2023 NEC, the … 210.11(C)(4), which referenced 210.52(G)(1)). I'll fetch both.
- Calling fetch_page
- Calling fetch_page
- Thinking
- Thought: I have solid confirmation: - NEC 210.11(C)(4): A 120V/20A branch circuit dedicated to … is enough; I'll present it as an example. Let's do 100 ft.
- Calling wiring_calc
- Thinking
- Thought: The tool interpreted "100" as meters (100 m = about 328 ft). That's too long. Let me redo it with a length in feet — the tool accepts units. I'll use "100ft".
- Calling wiring_calc
- Thinking
- Thought: The unit parsing was broken ("100ft" → 1e-13 m). I'll use explicit "ft" or a numeric … 20 A breaker is fine). Let me try the tool once more with "ft".
- Calling wiring_calc
- Thinking
- Thought: The tool's unit parser is broken for feet. I'll calculate it myself — this is a simple … e.g., Florida PBGC). Keep the answer concise and organized.
- Writing response
- Done · 8 tool calls · prefill 5.0 s for 12,946 tokens · 4,637 generated
