Bolt in connection box of motor cut off

[SA07]

Hi
One bolt in a motor connection box was cut off. Please see pictures. The screw material seems brass type and the nuts seems stainless steel. Is this normal? For such application should we tighten using torque wrench?
For other applications such as copper busbar, copper lugs fixation, can we use SS bolts, galvanised bolts? Thanks

 

[waross]

Silicon bronze is often used.

 

[Gr8blu]

Ideally the hardware (bolt and nut) will be non-ferrous material that is also non-galvanic and has sufficient tensile strength to deliver enough force to maintain a good electrical connection.

In practice, all kinds of hardware combinations get used.

Be aware that certain materials and finishes will also react with specific airborne contaminants to introduce corrosion, which may be accelerated by the presence of electrical current. Corrosion will tend to increase the resistance of the joint and/or reduce the mechanical force of the bond. Pick the hardware appropriately.