In this blog, we will break down two different building wires and how each of these differentiates from one another. The building wires that we'll be looking into are the popular CSA T90 & CSA RW90. Both of these constructions are designated building wires which are able to be applied to various applications within the commercial, manufacturing and other industrial markets.

Building Under Construction


What is the RW90 Cable

The CSA RW90 and RWU90 are available in 600 and 1000 volt constructions, which are reliable high-speed copper wiring products. These cables can be installed inside and outside but must meet the Canadian electrical codes of standards (CEC) requirements. The RW90 is regarded to be one of the best transmission constructions for above-ground applications, while RWU90 is also an efficient solution for underground applications. Lastly, RW90 is also commonly referred to as its UL XHHW counterpart, as both constructions are identical but are approved by different governing organizations.


RW90 Applications

The RW90 can be installed in outdoor systems but should be installed as the colour black because it's the only shade that's able to consistently withstand atmospheric weather. This cable is suitable for general-purpose wiring, power distribution and branch circuit wiring, where flame retardance is essential. The RW90 is also suitable for use in low leakage circuits (that require a dielectric constant of 3.5 or less, which is also a hospital-grade cable). 


These cables are typically installed in raceways and can be placed in cable trays if the installation setting is in dry or wet locations. Keep in mind that this must meet the code of standards in the Canadian Electrical codes (CEC). This construction is also available as "RWU90", which is appropriate for an application that uses up to 1000 volts. The additional "U" means this cable is approved for direct burial applications, but the electrician should refer to reliable sources to use them appropriately.

CSA RW90 7 Strand building Wire

CSA RW90 Construction

Cross-Linked Polyethylene (XLPE) insulation
600 Volts, 90°C
CSA Approved
*Comes in RWU90 for grounding applications


What is T90 Wire?

CSA T90 wire is categorized as a standard building wire that is traditionally required for residential, commercial and industrial markets. The T90 is a construction that has superseded the TW75 construction as consistently evolving standards required a higher temperature range for this type of cable. The main difference between the TW75 and T90 is the temperature range. The TW75 is only rated for 75C, while T90 is able to operate consistently in 90C. TW75, the older construction, also had its insulation made out of recycled PVC, compared to T90, which is made of standard PVC and has an additional nylon jacket for extra protection.


T90 Applications 

This type of construction is a general-purpose building wire that's utilized in installations in raceways and within dry and damp locations, with the exception of cable troughs. The CSA T90 building wire is also approved for use in ceiling fixtures, and with its easy sliding outer jacket, T90 installations are extremely reliable in tight application locations. 


The CSA T90 cable doesn't require any additional external lubricant for installation, as the slick material is able to slide through tight locations without issue. Similar to the RW90, the T90 construction can be used in conduit and cable trays for feeders, services, and branch circuits in industrial and commercial wiring. The CSA T90 is also known as UL THHN/THWN, as these are both very similar in construction but are approved by various organizations.


CSA T90 Construction

Polyvinyl chloride (PVC) insulation
Nylon jacket
600 Volts, 90°C
CSA Approved, CSA FT-1, UL THHN



The T90 and RW90 constructions are some of the most cost-effective and reliable building wires available. Being some of the most used building wires on the market, the T90 and RW90 are consistently available in multiple colours, gauge sizes and even different constructions. These versatile products are good for building applications, but all intended applications must meet the Canadian Electrical Codes (CEC) standards.

For more information on the different types of building wire and their different capabilities, feel free to reach out to our sales team ( One of our technical specialists will be more than happy to answer any questions you may have.