The usage time of an electric chain hoist can vary depending on several factors such as the frequency of use, the load capacity, maintenance schedule, and environmental conditions. Generally, electric chain hoists are designed to withstand heavy-duty applications and can operate for many hours continuously if maintained properly.

Here are some general guidelines:

1. Manufacturer Recommendations: Follow the manufacturer's recommendations regarding usage limits and maintenance intervals. They typically provide guidelines on usage time and maintenance schedules in the product manual.

2. Duty Cycle: Electric chain hoists are often rated with a duty cycle, which indicates the percentage of time they can operate in a given time frame. For example, a hoist with a 50% duty cycle can operate for 30 minutes out of every hour continuously.

3. Load Capacity: The load capacity of the hoist will also impact its usage time. Hoists operating at or near their maximum load capacity may experience more wear and require more frequent maintenance.

4. Environmental Conditions: Harsh environmental conditions such as extreme temperatures, dust, moisture, or corrosive substances can affect the lifespan and usage time of the hoist.

5. Maintenance: Regular maintenance, including lubrication, inspection, and part replacement as needed, can extend the usage time of the electric chain hoist.

6. Operator Training: Proper training of operators can also contribute to maximizing the usage time of the hoist by ensuring it is operated correctly and safely.

7. Overload Protection: Using overload protection devices can help prevent damage to the hoist and prolong its usage time by preventing it from being subjected to loads beyond its capacity.

It's essential to monitor the hoist's performance regularly and address any issues promptly to ensure safe and efficient operation. If there are specific usage requirements or concerns, consulting with the manufacturer or a qualified technician would be advisable.