> For the complete documentation index, see [llms.txt](https://delta-robotics.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://delta-robotics.gitbook.io/docs/get-started/safety.md).

# Safety essentials

The consolidated hazards of working with Delta artificial muscles, high heat, high current, LiPo batteries, fire, and mechanical force, and how to avoid each

Delta artificial muscles heat metal with high current from high-energy power sources. The hazards below apply to every ThermoFlex build and to any Nitinol wire or spring you drive. Treat each one as mandatory, not advisory. Read this page before your first run, and keep a way to cut power within reach at all times.

## High heat and burns

Nitinol muscles work by heating. In normal use the wire reaches its activation temperature of about 90 C, and shape-setting (training) runs the wire and its fixtures up to about 550 C.

{% hint style="danger" %}
**Hot wire and tools cause serious burns.** Wear heat-resistant gloves and eye protection, handle heated parts with pliers or tongs, and never touch a powered or recently powered muscle. Skin contact with wire at these temperatures causes immediate burns.
{% endhint %}

## High current

Muscles draw tens of amps. The Node delivers up to 60 A continuous shared across its outputs, and undersized or loose connections concentrate that current as heat.

{% hint style="danger" %}
**High current melts undersized wiring and connectors.** Use heavy-gauge wire (AWG 12 is the recommendation) and XT60 connectors, keep every connection tight and clean, and never run more than a few amps through jumper wires. Weak connections overheat, fail, and can ignite nearby material.
{% endhint %}

## LiPo battery handling

High-discharge LiPo packs store large amounts of energy and can dump huge current surges into a muscle with no limiting.

{% hint style="danger" %}
**A mishandled LiPo can vent, catch fire, or explode.** Use a pack rated for the job, such as a 3S LiPo with an XT60 connector, add an inline fuse or a current-limiting circuit, and choose a lower C-rating while you are learning. Never puncture, short, or overcharge a pack. Charge and store LiPos in a fireproof container away from flammables.
{% endhint %}

## Fire safety

Heat, high current, and LiPo packs together make fire a real risk, not a remote one.

{% hint style="danger" %}
**These systems can start a fire.** Work in a ventilated area, keep flammable and meltable materials clear of the muscle and wiring, and keep a fire extinguisher within reach whenever the hardware is powered. An unattended overheating muscle or pack can ignite its surroundings.
{% endhint %}

## Mechanical force and pinch points

Muscles contract with real pulling force, and a wire held under tension stores energy that releases suddenly if it snaps.

{% hint style="warning" %}
**Contraction force pinches, and a failed wire whips.** Keep fingers and loose clothing out of the line of pull, secure both ends of every muscle before powering it, and wear eye protection near tensioned wire. A pinch at full force injures, and a snapped wire can strike your face.
{% endhint %}

## The Node's auto-disable heartbeat

The Node disables its outputs about 2 seconds after it stops receiving commands from the host. A crashed script, a closed program, or an unplugged USB cable will not leave a muscle heating on its own.

{% hint style="info" %}
This heartbeat is a backstop, not a substitute for the precautions above. Two seconds of full current can still overheat a muscle, so keep the Node's button and a power cutoff within reach and do not rely on the timeout as your primary safety measure.
{% endhint %}

## Related pages

* [Quickstart: your first flex](/docs/get-started/quickstart.md): Run your first contraction with these hazards in mind.
* [First time flexing your muscles](/docs/tutorials/thermoflex/getting-started-with-our-evaluation-kit/first-time-flexing-your-muscles.md): Calibrate a safe run time before automating.
* [TF Node Controller](/docs/hardware/thermoflex/tf-node-controller.md): Current limits, connectors, and the heartbeat behavior.
* [Mounting and wiring](/docs/hardware/nitinol/mounting-and-wiring.md): Make high-current connections that hold.