This article explains a popular form of copper tray cable called XLP or sometimes referred to as XLPE tray cable. XLP tray cable is a 600 volt product that can be direct buried or installed in cable tray.
XLP stands for cross linked polyethylene. The XLP is the insulation part of the tray cable. In other words, it is the material that covers the copper conductors in the construction of the tray cable. Over this insulation is a jacket compound such as a thermoplastic PVC (polyvinyl chloride) or a thermoset CPE (chlorinated polyethylene). PVC is more common due to its low cost and higher availability.
The main reason an electrical contractor would prefer a XLP tray cable over one insulated with PVC such as a VNTC tray cable is the XLP compound has superior resistance to fire, moisture and chemicals. In other words, this product is a better option in most hazardous locations where cable durability is critical due to severe elements.
Sizes of XLP tray cable range from 500 MCM to 14 AWG. Circuit sized XLP tray cable (10, 12, & 14 AWG) offer higher conductor options (5/c or more). The power sized XLP tray cable (8 AWG and larger) typically are manufactured 3/c and 4/c with a bare ground. Like most tray cables, this product can be purchased with a shield in the circuit sizes where electromagnetic frequencies could cause interference to the signal.
The drawback to XLP tray cable verse VNTC tray cable is the cost. Depending on the manufacturer, XLP tray cable with a PVC jacket can increase the cost between 10-20%. This can be a significant amount of money in the power sizes or if you require large quantities of tray cable for your job. However, the superior construction of the product should be used when flame retardance is required.