A Comprehensive Guide To Tray Cables
While it is quite evident based on its name, tray cable is a cable with two or more conductors designed to be used in a cable tray. Tray cables follow a separate group of UL and NEC specifications and are more sturdy and resistant to heavy abrasion compared to other categories of cables. The cables are overwhelmingly used in industrial, mining, and oil field applications and are placed inside raceways and cable trays.
Read this guide to understand the specifications of tray cables and choose the perfect tray cable for you.
Can Tray Cable Be Used In Residential Applications?
While it was prohibited for the longest time, as per the 2017 installment of the National Electrical Code, tray cables can be used in houses only without being installed in the cable tray. Inside, the cable should adhere to the rules of NM-B installation, and outside, it should follow the rules typically reserved for UF-B.
As for commercial wiring, tray cables are very common in office buildings as long as the installation and the cable tray adhere to the NEC standards.
Should I Go with a Shielded or an Unshielded Tray Cable?
Use shielded tray cables only in applications where there is a risk of electromagnetic interference from power stations or simultaneous processes happening in an industrial setting. Electromagnetic interference is quite common in the industrial environment for motor production, welding machines, and frequency inverters. However, an unshielded cable is quite enough in most regular industrial settings, and it is way cheaper.
Types of Tray Cable According to The Electrical Rating
While all tray cables are meant to be installed in the cable trays, their applications are actually very different depending on UL and NEC ratings. Let's slide through some of the most popular and less common types of tray cables according to the rating.
Main Ratings of Tray Cables
Type TC, which basically means tray cable, is the most popular type of tray wire that you will find on the market. This cable corresponds with the standards found in NEC article 336. It is a flame-retardant cable for power and control types of circuits in industrial settings acceptable for cable trays. If paired with the messenger wire, this cable can be used outdoors. The cable can only be used for direct burial in case the specifications say so.
TC vs. TC-ER: What is the difference between TC and TC-ER cables?
TC-ER reads as an exposed run tray cable. It is the subtype of the TC cable that is allowed to run free between the cable trays for an average distance of six feet. TC-ER rating means that the cable is subjected to the most rigorous crash and impact requirements than the standard TC cable. Since there are areas where TC-ER cables are not protected by the tray, the installment cost of these cables is lower than the tray cable average. Remember that exposed run is not the same thing as direct burial, so a TC-ER should have a separate rating for it.
PLTC vs ITC
Type PLTC is a power-limited tray cable corresponding to the standards found in article 725 of the National Electrical Code. The cable is used in power and control circuits that are rated at 300 volts. They are used in Class 3 and Class 2 circuits.
Type ITC is an instrument tray cable per NEC 727 used exclusively in control and instrumentation circles up to 150 volts. They are allowed for direct burial. Many tray cables on the market are currently double-rated as PLTC/ITC. Both of those cables can also be rated for an exposed run.
Other Tray-Rated Cables
Metal-clad cable, which is also well-known under the name Type MC, is a cable put inside the armor or the metal tape. This cable type is rated for cable trays according to the applications listed in NEC 330 and NEC 725 hazardous locations. The cables are generally versatile and are permitted for use in Class 1 Division 1 dangerous locations both inside and outside. The cable can also be rated for direct burial.
However, it is prohibited for applications that might be damaging for the cable armor. The reason that type of MC cable is sometimes used in trays is that it acts as a cheaper replacement for other types of tray cables that would have been placed in conduit.
VFD Cable. Variable frequency drive cable, also known as variable speed drive cable, is a type of cable designed specifically for use within a variable frequency drive system. However, it is also rated as a TC cable and may also be rated as TC-ER. Basically, if VFD is available to you, you can use it as a variation of shielded tray cable.
Depending on the particular subtype, fiber optic cables and fire alarm cables can also be used in cable trays. Consult NEC Article 770 if you wish to put a fiber optic cable in a cable tray or Article 760 if it makes sense for your electrical project to put a fire alarm cable into the cable tray.
Types of Tray Cables According to Jacket/ Insulation
Aside from the rating, the thing you should keep in mind while choosing the tray cable for your project is the quality of the jacket and insulation. Here are the most common combinations of tray cables on the market:
XLP/PVC tray cables have a duo of XLPE insulation and a PVC jacket. This is one of the cheaper variations of tray cables available on the market. Still, it is physically tough and has high dielectric strength, as well as excellent resistance to chemicals and oil. The maximum temperature range is +90°C. The cable comes with an XHHW-2 conductor and is rated for direct burial.
EPR/CPE are flame-retardant and double-rated cables that have great resistance to weather and UV lights. Compared to XLP/PVC, these cables are more heat-resistant and are more flexible. These cables are also a TC-ER. FREP/CPE is the variation of the same wire with a more excellent flame-retardant insulation. Out of the standard tray cables, the ones with this particular pair of jacket/insulation tends to be more pricey.
THHN/PVC is the cheapest variation of the tray cable construction with a thermoplastic jacket. It is suitable for direct burial.
All of these cables are suitable for Class 1 Division 2 applications.
There are also tray cables on the market with jackets double-rated as low-smoke zero halogen (LSZH). These cables emit less harmful gases if the fire occurs.
Types Of Tray Cables Illustrated
We hope that this guide was perfect for you when it comes to selecting an ideal tray cable. For high-quality tray cables at reasonable prices, pick from the Nassau National Cable collection.
