Electric Arc Length|Short,Medium, Long Arc

Electric arc length is the straight distance between the electrode tip and the job surface when the arc is formed.

There are three types of arc lengths:

Medium or normal
Long
Short

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Contents

Medium, normal electric arc

The correct arc length or normal arc length is approximately equal to the diameter of the core wire of the electrode.

This is a stable arc producing steady sharp cracking sound and causing:

Even burning of the electrode
Reduction in spatters
Correct fusion and penetration
Correct metal deposition

It is used to weld mild steel using a medium coated electrode. It can be used for the final covering run to avoid undercut and excessive convex fillet/ reinforcement.

Long electric arc

If the distance between the tip of the electrode and the base metal is more than the diameter of the core wire it is called a long arc. It makes a humming sound causing:

unstable electric arc
oxidation of weld metal
poor fusion and penetration
poor control of molten metal
more spatters, indicating wastage of electrode metal.

It is used in plug and slot welding, for restarting the arc and while withdrawing the electrode at the end of a bead after filling the crater.

Generally long arc is to be avoided as it will give a defective weld.

Short electric arc

If the distance between the tip of the electrode and the base metal is less than the diameter
of the core wire, it is called a short arc.

It makes a popping sound causing:

the electrode melting fastly and trying to freeze with the job
higher metal with narrow width bead
less spatters
more fusion and penetration.

It is used for root runs to get good root penetration, for positional welding and while using a
heavy coated electrode, low hydrogen, iron, powder and deep penetration electrode