You're right, you can't simply split a single NC contact into three separate NC circuits. The contact is physically breaking and making contact in one place, so it can only switch one circuit at a time.Here's a breakdown of your options and why they work (or don't)

Why You Can't Split the NC Contact:
Physics

The NC contact works by physically connecting two wires. When the button is pressed, it physically disconnects those wires. You can't physically disconnect one connection into three separate disconnections.

Reliability

Emergency stop circuits are designed for safety. Splitting a single contact to control multiple circuits would introduce a single point of failure. If that split point fails (wire breaks, corrosion), you lose all three circuits, defeating the purpose of redundancy.

Your Options

1.

Find a Different Pendant with More Contacts

This is the best and safest solution. Look for pendants specifically designed for E-Stop applications that offer more contacts. Many industrial pendants have modular contact blocks that can be configured to your specific needs. Specify 3NC and 1NO configuration.2.

Use a Safety Relay with Expansion Capabilities



How it works

A safety relay is a specialized relay designed for safety applications. It monitors the E-Stop button and other safety devices. When the E-Stop is activated, the safety relay de-energizes, opening its normally closed contacts.

Expansion

Some safety relays have expansion modules that allow you to add more output contacts (both NO and NC). You would connect the pendant's single NC contact to the safety relay's input. The safety relay's output contacts would then provide your 3 NC circuits.

Advantages

This provides the most robust and safe solution as it includes a safety device that monitors the circuit.

Disadvantages

This is more expensive and requires additional wiring and mounting space.3.

(Less Recommended, But Possible with Caution) Use Additional Relays



How it works

You can use the existing NC contact on the pendant to control the coils of three separate industrial relays. Each relay would have a normally closed contact. When the E-Stop button is pressed, the NC contact on the pendant opens, de-energizing all three relay coils. This causes the NC contacts on each relay to open, effectively giving you your 3 NC circuits.

Advantages

Cheaper than a safety relay initially.

Disadvantages



Less Safe

Relays can fail. If one relay coil fails to de-energize, you've lost one of your E-Stop circuits. This significantly reduces safety compared to a dedicated safety relay.

Not Best Practice

This approach is generally frowned upon for critical safety circuits.

You need relays with force guided contacts to be sure the relay contact is open when the relay is unpowered.Important Considerations for E-Stop Circuits



Safety Standards

E-Stop circuits are governed by strict safety standards (e.g., ISO 13849-1, IEC 60204-1). You must understand and comply with these standards. Failure to do so can lead to serious injury or death.

Redundancy

Multiple contacts (like your 3NC) provide redundancy. If one contact fails, the other will still shut down the machine.

Self-Monitoring (For Safety Relays)

Good safety relays will self-monitor for internal faults.

Documentation

Thoroughly document your E-Stop circuit design, including the components used, wiring diagrams, and testing procedures.

Competent Person

Have your design reviewed and approved by a qualified safety professional.

Recommendation

Start by searching for a pendant with the correct contact configuration (3NC, 1NO). If you can't find one that meets your needs, use a safety relay with expansion capabilities. This is the safest and most reliable approach. Only consider using standard relays as a last resort* and only if you fully understand the risks and can mitigate them.

In summary, you can't split the NC contact from the button. The recommended solutions are to either find a different pendant that meets your requirements or use a safety relay with expansion capabilities. Flag for review