Cable Construction & Product Design
Questions about conductor materials, shielding, cable components, jackets and product design configurations.
A:
Unilay and compressed strand are both types of cable strand constructions, but they differ in how the strands are arranged and how they're manufactured. Unilay stranding involves all layers of strands being twisted in the same direction, while compressed stranding involves compressing the strands together to reduce the overall diameter.
Unilay Stranding
Layout
- All layers of strands are twisted in the same direction, creating a more compact and lighter cable than a traditional concentric lay
Lay Length
- Each layer has the same lay length
Manufacturing
- Strands are typically twisted together into layers, then may be further processed to compact the overall structure
Advantages
- Offers a smaller diameter and lighter weight compared to traditional concentric lay.
Compressed Strand
Layout
- Similar to concentric lay, but the strands are squeezed together to reduce the overall diameter of the cable
Manufacturing
- Strands are first twisted together and then pressed or pulled through a die to reduce the diameter
Reduction in Diameter
- The diameter of a compressed strand is typically no more than 3% smaller than a non-compressed conductor of the same cross-sectional area
Advantages
- Provides a more compact and potentially stronger cable
Compressed strands are pressed down in size from 1 to 3%.
See 3rd from left below.
Combination Unilay Strand
Both layers have a common lay length and direction. Combination Unilay produces a round but softer alternative to compressed conductors. Compressed Combination Unilay provides an even smother surface but harder and with slightly less flexibility. Suitable for thin wall or semiconductor insulation.
In the LS catalog, there is a footnote for 8AWG conductors noting combination unilay-stranded, which means two different size strands are used to get a 3% reduction similar to compressed, but without compressing the strands.
Bottom-line, if you want to reduce the size of the conductors by 3%, you have two options; compress the conductor with a die, or use combination unilay with two different strand sizes to get the strands to fit together tighter without compressing them.
8AWG conductors are the only LS Cable products that use combination unilay-strand.
A: It’s not designed to be a current-carrying conductor. The main purpose is to reduce the electrical stress on insulation. But in fault conditions, it can act as a short circuit current carrying path and maximum capability depends on the calculation per ICEA P-45-482. (But it all depends on several factors being met at certain categories and criteria)
A: As a metal material, aluminum plays an essential role in different industries. It's flexibility, durability and light weightiness have made it a go-to option for many engineers, designers and manufacturers. However, not all aluminum types are the same. In particular, 1350 and 8000 aluminum alloys have distinctive properties that make them suitable for various functions.
A: LS Cable & System USA utilizes Chase BIH20ck in its strand filled products. See details below.
A: Yes, we can.
A: We do not offer MV-105 CTS with EPR jacket. EPR is an insulation material, not jacket material. Our Engineering team advises that a different EPR compound may be formulated for use as jacketing material (see below), but our current EPR compound is not and does not meet the standards we currently manufacture to (UL and ICEA). Of course, a customer may choose not to have it meet the standards we manufacture to, but it is unlikely that we source an additional jacket material unless there was a substantial upside.
A: Our VFD cables use a copper tape over XLPE conductors, so yes, we have the capability to make this cable. Tape thickness is 10mil vs. our standard 5mil. It is odd that there is no ground wire in contact with the shield, perhaps the metal tape is for rodent control? Please note that we are not currently quoting VFD cables at this time.
Ratings, Standards & Testing
Questions about flame performance, UL listings, cable ratings, standards and field testing requirements.
A: Our cables are not tested by IEEE 383 & 1202 standards, however, we meet the UL Flame Exposure test listed in UL 1685.
A: Our 15kV EPR/CTS/PVC cables meet the following requirements:
- Single cables 1/0 AWG and larger
- Per UL 1685 (Flame exposure) and UL 2556 Method 1 vertical tray flame “For CT-USE” marking per UL 1072. (Exception IEEE 383 and 1202 flame test compliance).
- Multicore cable 2 AWG and larger
- Per UL 1685(Flame exposure) and UL 2556 Method 1 vertical tray flame “For CT-USE” marking per UL 1072 (Exception IEEE 383 and 1202 flame test compliance)
A: LS MV-105 products are UL Listed. UL Certificate of Compliance attached below.
A: LS does not have a low smoke, zero halogen (LSZH) compound for any of our cables. Also of note, UL nor ICEA offer this compound for MV cable.
A: Yes, our MV cables meet UL 1685 Flame Exposure test per UL 1685 as noted in our catalog.
A: In the image below, the red boxes indicate the industry specification that products are manufactured to. If there is a spec reference other than ULXXXX or ICEAXXXX, it is a non-standard product. A non-standard product may have different colors, markings, dimensions, compound, etc. per a customer's request or specification.
We see many inquiries on MV URD cables where a customer wants MV-105 rated URD. These inquiries are usually in response to a competitor's spec where the EPR URD indicates:
- 105C continuous operating temperatures
- Can be listed by UL as Type MV-90 on special orders
- Improved temperature rating (Insulation system has been tested and qualified for operation at 105C continuous and 140C emergency operating temperature)
Our MV URD for EPR/CN/LLDPE indicates designed to operate continuously at a conductor temperature not exceeding:
- 105C for normal operation
- 140C for emergency overload
- 250C for short circuit
Overall, these products are rated with a continuous operating temperature not to exceed 105C and none of our competitor's spec (nor ours) indicate that the product will be market 'UL MV-105'. The only UL marking that any manufacturer can put on the print legends of these products is MV-90.
When comparing to competitor specs the way they are written can be confusing, but essentially, they provide the same product as LS.
Installation & Applications
Questions about cable applications, installation, reel packaging, storage and project-specific use cases.
A: None of our MV UD (concentric neutral shield) cables meet both MV-105 and flame test CT-USE requirements. If MV-105 and CT-USE are needed, we can provide MV-105 cable (EPR/CTS [copper tape shield]/PVC jacket; Series G) However, the critical difference is that the metallic shield is not the same, thus MV-105 is not a proper alternate. The metallic shield is related to cable systems, so it should be engineered by user’s engineering division.
A: Yes, we can manufacture LV tray cables similar to Belden, but with notable exceptions (see below):
Can reels be stored outside in the elements without being inside in a climate-controlled atmosphere?
A: Yes, LS packages reels with a level 2 reel wrap which provides adequate protection for storing reels in outdoor or inclement weather (see below).
Typically, additional packaging materials are required for cable that will be stored outside. See NEMA WC 26, 2008 Edition, 2008 - BINATIONAL WIRE AND CABLE PACKAGING STANDARD
This standard covers uniform requirements for packaging electrical wire and cable and replaces the following NEMA/EEMAC standards
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