Have you ever noticed the writing on a cord or cable on an item in your house and wondered, “What does all of this mean?”. You are not alone! Today we will take a closer look at the alphabet soup of those seemingly random letters to see what those markings mean. A few weeks ago, we discussed how to read the markings on regular wire. If you have not read that article yet, we would recommend it as we will build on the knowledge learned from that article today. You can check it out here: https://ctwireprep.com/wire-characteristics-how-to-read-inkjet-markings-on-wire/.
When it comes to cords and cables, much like wire, there are many types. One of the biggest visual differences other than color is, some cords are flat, and some are round. A cord that is flat will have the letter P in its cord type. The P stands for Parallel since the individual wires inside run parallel to each other. An S will signify that the individual wires inside the cable have Stranded wire cores. Two common examples of flat cable types are:
- SPT – Stranded Parallel Thermoplastic. You will always see SPT cable with a -1, -2, or -3 on the end. These numbers specify the thickness of the insulation. The application the cable is being used for will determine which number is required.
- HPN – Heater Parallel Neoprene. Chances are, you have at least one small appliance in your house with this type of cable as it is required where a heater element is used. Examples would be a toaster or an iron.
There is a list of 6 standard letters that are used on cables that are rated (by CSA and/or UL).
- S = Stranded or Service wire and is 600 volts
- J = Junior Service and is 300 volts. If there is no J, then it will be 600 volts
- T = Thermoplastic (the jacket on the cable). If there is no T, then the jacket is made of rubber.
- O = Oil-Resistant Compound
- W = Weather Resistant Compound
- V = Vacuum – yep, as in vacuum cleaner. This type of wire used to be used exclusively for vacuum cleaners but is now used for many other applications. This OD (Outside Diameter) of the jacket on this wire is small which allows for greater flexibility.
That takes care of the most common letters. In addition to these you will also see number combinations. For example, you will see 18/3. The number before the / is the gauge (AWG) of the inside conductors. The number after the / is how many conductors are inside.
Let’s take a look at some examples!
18/3 SJOOW is one we see a lot of at C-T Wire Prep Inc. When we break down this combination, we can tell the characteristics of the cable are:
18 / 3 S J O O W
- 18AWG
- 3 conductors
- Stranded (Service Wire)
- Junior Service (300 volts)
- Oil-Resistant Compound
- Weather Resistant Compound
Okay, that is great, but what about the additional O that we missed on the list? The second O tells us that the insulation on both the inside 3 conductors as well as the exterior jacket of the cable are both made with Oil-Resistant Compounds.
16/3 SPT-3 is one that you may have in your house. Or one that is very similar. This type of cable can be found as part of the power supplies that power consumer electronic devices in your home. Let us break it down together.
16 / 3 S P T -3
- 16AWG
- 3 conductors
- Stranded (Service Wire)
- Parallel (flat cable)
- Thermoplastic (jacket insulation)
- -3 – the thickness of the jacket
We hope you found this article educational and that it will help you identify cables in the future. As always, if you have any questions, please reach out to us and we will be happy to answer them.