Safety

Risks

• Mains Voltage Electrocution
• Fire

High voltage AC current can be fatal, and fire can endanger your family.

Please ask for someone's help, if it's outside of your comfort zone. They will probably be glad to do so rather than you risking your life.

Guidelines

Always

• Keep the AC side isolated from physical access.
• Never work on the AC side without unplugging the power cable.
• Keep a fire extinguisher within reach.
• Turn off the power and avoid hot-plugging jumpers or cables.
• Don't leave your printer unattended for long periods.
• Inform someone when printing, and ensure you have a camera, VPN access, and a backup system like a smart smoke alarm connected to a remote relay.
• Stay informed and proactive.

Research

• Understand the power usage of your components.
• Familiarize yourself with cable wire ratings and ampacity.
• Check connector and crimp maximum ratings.
• Verify the circuit amperage and heat ratings of your PCBs.
• Confirm the current ratings of your MOSFETs and SSRs.
• Use DC AC fuses rated to ~125% of your maximum usage.
• Opt for flame-retardant materials for your enclosures.

Safety Systems

• Test how your system's design prevents or mitigates unsafe consequences in case of failure.
• Consider the system's reaction to fast or slow failures.
  • A slow-discharged short through a resistance that won't trip fuses.
  • MOSFETs and SSRs failing in a closed circuit, leading to thermal runaway.
  • Short circuits on high-voltage sources.
  • Accumulated heat on improper connectors with high resistance.
  • Potential issues like software safety systems freezing or going offline.

General Tips

• Avoid inserting tinned wire into screw-down terminals. Crimp ferules or twist the bare copper wires instead.
• Ensure no AC bare wires are exposed.
• Don't insert ferules or tinned wires into WAGO type connectors.
• Check the tightness of spade connectors (NOT when powered) and surrounding temperatures after a few minutes of operation.
• Use genuine connectors and crimps for high current lines.
• Test your crimping technique's strength and durability on some spare pieces of cable.
• Secure cables with strain reliefs.
• Choose appropriate cables for motion applications.
• Watch out for potential wear and drag fatigue damage.

Material hazards

• When cutting, drilling, or sanding carbon fiber or glass fiber, work in a well-ventilated area and wear a respirator mask. Wetting the surface helps minimize airborne particles.
• Please research safety recommendations for processing carbon fiber or other composite materials.

Note: These are common sense tips based on my personal experience, and are not coming from an authorized professional. Always exercise caution and seek professional advice if needed.