Okay, let's break this down to understand the potential for overheating. A "throw switch" in this context likely refers to a disconnect switch, designed to break the flow of current to a panel.

Understanding the Setup 240V Throw Switch

You have a disconnect switch rated for 240 volts.

4 Terminals (2x2)

The switch has four terminals, physically arranged as two pairs.

Line Side

This is the side connected to the power source (the utility or another panel).

X1 and X2 (Only)

You're only using two of the terminals on the line side – labeled X1 and X2.

208V 3-Phase Panel

The throw switch feeds a 208V, 3-phase panel.

Wiring

The conductors are 1/0 AWG (American Wire Gauge).

Wiring Description

X1 is connected to it's own terminal and X2 & X3 are tied together on one terminal.

The Potential Problem: Uneven Current Loading and Terminal Overheating

Yes, the way you've described the wiring configuration presents a significant potential problem that can lead to overheating of the conductors, the terminal connections, and potentially the switch itself. Here's why:1. Single-Phase to Three-Phase Incompatibility

You cannot reliably feed a 208V 3-phase panel with only two legs (X1 and what appears to be a combined X2 & X3) from a 240V single-phase source. A three-phase panel requires three distinct phases (L1, L2, L3) separated by 120 electrical degrees. By tying X2 & X3 together, you are only creating one distinct phase, and you're essentially shorting those two phases together. This is a recipe for disaster.2.

Overcurrent and Imbalance

When you attempt to power a 3 phase system with two legs tied together, the system will try to compensate by pulling excessive current through the available paths. This will cause the conductors you're using to carry more current than they were intended to, which will lead to the copper strands expanding and contracting constantly, leading to conductor failure.3.

Terminal Overloading

Terminals are rated for a maximum amount of current. The fact that you are connecting two phases to one terminal, means that you're doubling the amount of current it is designed to carry. This will lead to overheating and eventual failure.

1/0 AWG Conductor Capacity

1/0 AWG copper conductors are rated for a specific ampacity (current-carrying capacity) according to the National Electrical Code (NEC). The exact ampacity depends on the insulation type and the installation conditions (e.g., temperature rating of the conductors, if they are in free air or conduit, and the ambient temperature). A general rule of thumb, THHN/THWN-2 1/0 AWG copper wire is rated for about 150 amps in a 75-degree C environment.

In Conclusion Immediate Danger

Stop using this setup immediately. It is a fire hazard and could damage equipment.

Correct the Wiring

You must have a proper 3-phase source for your 208V 3-phase panel. The wiring described is fundamentally incorrect.

Consult a Qualified Electrician: You need to have a licensed electrician evaluate your power source and determine the correct way to connect the 208V 3-phase panel. They will be able to assess the situation and make the necessary changes to ensure a safe and code-compliant installation. Flag for review