Size and price:
The average dig depth for utility installations in residential applications is between 40 and 48 inches. The basic trencher that digs to the above depth will boast a 20 - 30 horsepower engine and cost around 40,000 dollars.
The most popular type of compact excavator is the 2.5 metric ton size class, and it uses a 30 HP engine and costs around the same price. The biggest difference in the two surfaces when you need the trencher to dig deeper. The 2.5 metric ton excavator has no trouble at all digging to 8 feet or more, although a trencher that can dig that deep will require an engine with around 100 horsepower and cost upwards of 90,000 dollars!
Life costs:
Not counting the bucket teeth and the replacement of the rubber tracks at 2,000 hours, fuel and routine maintenance are your only daily costs with a compact excavator. The digging chain, teeth, and sprockets on the trenchers are considered wear items and need to be replaced often. Even with the high consumable costs of trenchers, the differences will tend to even out when productivity is taken into effect.
Productivity:
For straight line trenching at an average depth, trenchers will flat out lead compact excavators. Under reasonable conditions, a trencher can work three to four times faster than that of a compact excavator. Another area where trenchers really excel is wooded areas, where tree roots and logs can make for slow and sloppy digging when using a bucket.
Versatility:
When it comes down to it, compact excavators can do a lot of things that trenchers can't, especially when they have attachments on hand. If you are digging with a compact excavator, you can't go anywhere near as fast as you can with a good quality trencher.
Keep in mind that a trencher isn't a single minded machine either. Most styles of trenchers can be outfitted with a backhoe attachment that attaches to the front end. Whenever concrete, rocks, or asphalt stands in the way, the boom and chain can be replaced with rock teeth and a wheel. In soft soils, you can set up a trencher with a plow attachment and plow in cables faster than using any other available method.
When it comes down to choosing, keep in mind that it all depends on your needs. There are some cases where the compact excavator is best to choose, while there will also be jobs in which the trencher is going to do the best work.
