Tools in This Collection
Breaker Size Chart
Circuit breaker sizes for common household circuits by wire gauge
Wire Nut Size Chart
Wire connector sizes by wire gauge and count
HVAC Refrigerant Chart
Properties and compatibility of common AC refrigerants
Welding Rod Chart
Electrode types and applications for stick welding
How to Read an Electric Meter
Analog and digital electric meter reading guide
Propane Tank Size Chart
Propane tank capacities, BTU content, and applications
Electrical and HVAC Quick Reference
Electrical and HVAC work depends on getting specifications exactly right — undersized wire overheats, wrong refrigerant damages compressors, and incorrect breaker sizing creates fire hazards. These reference charts give you the correct specifications quickly, whether you're on a job site or planning work from the office.
Breaker Sizing: Circuits and Wire Gauges
Circuit breaker sizing follows a clear pattern based on wire gauge and load type. Standard residential lighting circuits use 14 AWG wire with 15A breakers. General purpose outlets use 12 AWG with 20A breakers. Kitchen and bathroom circuits require dedicated 20A circuits. Major appliances: dryer 10 AWG/30A, electric range 6 AWG/50A, electric water heater 10 AWG/30A. Air conditioners vary — check the nameplate for minimum circuit ampacity (MCA) and maximum overcurrent protection (MOCP). The Breaker Size Chart covers all standard circuits with wire gauge, breaker size, and common applications.
Wire Nut Color Codes
Wire nut sizes are color-coded by manufacturer but follow a general convention: yellow for 2 wires of 14 AWG, red for 2-3 wires of 12 AWG, orange for 2-4 wires of 14-16 AWG, grey for large connections (3-4 wires of 12 AWG or combinations). Always check the specific product's range printed on the package — colors are not perfectly standardized across brands. The Wire Nut Size Chart shows the minimum and maximum wire combinations for each connector type by gauge and count.
HVAC Refrigerants
The shift away from R-22 (phased out under the Montreal Protocol) means most residential systems now use R-410A, though newer systems increasingly use R-32 and R-454B for lower global warming potential. R-410A operates at higher pressures than R-22 (up to 600 psi) and is not a drop-in replacement — different compressors and service equipment are required. The HVAC Refrigerant Chart covers properties, pressures, and compatibility for all common residential and commercial refrigerants. The Propane Tank Size Chart shows standard tank capacities (20 lb, 100 lb, 250 gal, 500 gal, 1000 gal) with BTU content and typical applications.
Welding Rods and Electric Meters
The Welding Rod Chart covers common stick welding electrodes: E6010 for root passes on pipe, E6013 for light fabrication, E7018 for structural steel. The number codes indicate tensile strength (first two digits × 1000 psi), welding position (third digit), and flux type/current (fourth digit). The How to Read an Electric Meter guide explains analog and digital electric meter displays, including how to calculate consumption between readings and what time-of-use rate periods look like on smart meters.
Frequently Asked Questions
What breaker size do I need for a 20-amp outlet circuit?
A 20-amp outlet circuit requires a 20A breaker and 12 AWG wire. Standard lighting circuits use 15A breakers with 14 AWG. The breaker amperage must match or be lower than the wire's rated capacity — never use a 20A breaker with 14 AWG wire (which is rated for only 15A). Dedicated circuits for kitchen appliances, bathroom outlets, and garage outlets are required to be 20A by the NEC.
Can I replace R-22 refrigerant with R-410A?
No. R-22 and R-410A are not interchangeable. R-410A operates at significantly higher pressures (up to 600 psi vs R-22's 275 psi) and requires different compressors, service equipment, and refrigerant lines. Mixing them damages the system. R-22 equipment that needs refrigerant can use drop-in replacements like R-422D or R-438A in some cases, but full replacement with R-410A equipment requires replacing the entire system.
How do I choose the right wire nut size?
Wire nut selection depends on the number and gauge of wires being connected. As a general guide: yellow connectors handle 2-3 wires of 14-16 AWG; red connectors handle 2-4 wires of 12-14 AWG; orange connectors handle 2 wires of 14-16 AWG for smaller connections. Always verify the specific product's wire range on the package — colors are not standardized across brands. When in doubt, use a larger connector and test by tugging each wire after installation.