Choose water-blocking tape by layer electrical class first. A non conductive water blocking tape and a semi-conductive grade may both swell after water ingress, but they do not perform the same electrical job. Confirm whether the layer must stay insulating or provide controlled continuity, then verify resistance, mechanical and swelling requirements.

Non Conductive Water Blocking Tape vs Semi-Conductive Tape: Start with the Layer

Water blocking and electrical behavior are separate specification axes. The absorbent system helps occupy internal gaps after contact with water. The electrical classification determines whether the dry tape should resist current flow or provide a controlled resistive path at an interface. A tape should not be called non-conductive merely because its product name omits the word “semi-conductive.”

• Specify a non-conductive grade where the design requires water blocking without intentional electrical continuity through the tape. Define the required evidence rather than relying on a generic “insulating” description.
• Specify a semi-conductive grade where the cable drawing requires water blocking together with controlled electrical continuity adjacent to a conductor screen, insulation screen, metallic screen or another defined layer.
• Do not select by voltage class alone. A single power-cable construction can contain non-conductive tape in one position and semi-conductive tape in another. The cross-section and interface function govern the choice.

A published Jicable technical paper on fully water-blocked power cable design illustrates this layer-specific approach: its example construction uses non-conductive and semi-conductive water-blocking materials at different positions in the same cable. That example is not a universal recipe, but it shows why a buyer should identify the layer before naming the tape category.

How to Read Water Blocking Tape Electrical Resistance Data

Surface resistance and volume resistivity are not interchangeable. Surface resistance concerns current flow along a material surface and is commonly reported in ohms. Volume resistivity relates the measured resistance to specimen geometry and is commonly expressed in ohm-centimetres. The IEC treats these as separate DC test topics in IEC 62631-3-2:2023 and IEC 62631-3-1:2023. These links explain the measurement distinction; they do not certify a Chaowang tape to either method.

Resistance results depend on the stated method, electrode arrangement, applied voltage, conditioning, temperature, humidity and specimen geometry. An RFQ should therefore include the required property, limit, unit and test method. Values copied from two datasheets are not directly comparable when one uses a different fixture or reports resistance while the other reports resistivity.

The official CW-8 semi-conductive water blocking tape page explicitly states a construction of polyester non-woven fabric, superabsorbent resin and semi-conductive adhesive. For its published BZSD30, BZSD40, BZSD50 and BZSD60 grades, the table lists surface resistance below 1,500 Ω and “volume resistance” below 1 × 10^5 Ω·cm. Because Ω·cm is a resistivity unit, buyers should retain the supplier’s published wording in the comparison record and request the current grade-specific method before approval.

By contrast, the CW-5 non-woven water blocking tape page states polyester non-woven fabric, superabsorbent resin and adhesive, but it does not explicitly publish a non-conductive classification or electrical-resistance value. Do not infer that CW-5 is non-conductive. If a design needs that classification, request written grade-specific evidence and test the proposed material against the cable specification.

Match the Tape to the Cable Layer, Adjacent Materials and Process

1. Mark the exact position. Supply a controlled cable cross-section showing whether the tape contacts a conductor, extruded screen, screen wires, metallic barrier, armour, bedding or sheath.
2. State the electrical function. Write “non-conductive” or “semi-conductive” as a requirement, then add the applicable resistance or resistivity limit, unit, conditioning and test method.
3. Control the physical interface. Define nominal thickness, tolerance, width, coverage, overlap, active face or faces, and the permitted change in cable diameter. Confirm compatibility with adjacent compounds and metals.
4. Check manufacturing behavior. Review tensile strength, elongation, winding quality, edge condition, powder shedding, roll dimensions, splice allowance, line speed and application tension.
5. Validate water blocking separately. Agree on swelling rate or height only when the test medium, time, temperature and method are stated, then verify the completed cable using its required water-penetration test.

Product-family names also need discipline. The CW-1 cable-core binding tape is presented for binding, not as a published swellable water-blocking product. The broader non-woven cable tape range helps buyers compare functional families, but a non-woven carrier alone does not establish water-blocking or electrical performance. For swelling and dimensional selection details, use the separate CW-5 construction and specification guide.

Write the RFQ Around Evidence, Not the Product Label

A usable RFQ lets the supplier select a grade without guessing. Include the cable type, rated voltage where relevant, the marked tape position and every adjacent material. State whether the layer needs non-conductive or semi-conductive behavior and provide the electrical acceptance criteria. Add tape dimensions, application direction, overlap, production speed, roll geometry, water test medium and finished-cable test.

Request the current technical datasheet, the declared test methods, a representative sample and the batch document that will accompany production material. During the line trial, record tracking, wrinkles, breaks, dusting and final core diameter. After the trial, inspect the interface and perform the electrical and water-penetration checks required by the cable design. A reference such as IEC 60840:2020 governs specified power-cable systems within its scope; it should not be presented as a tape certification.

Frequently Asked Questions

Is every polyester non-woven water blocking tape non-conductive?

No. Polyester non-woven describes a carrier material, not a verified electrical classification. Adhesives, coatings, additives and construction all matter. Require a grade-specific electrical statement and the relevant test result before approving a tape for an insulating position.

Can tape color identify a semi-conductive grade?

No. Appearance is not acceptance evidence. A dark tape may contain conductive material, pigment or another coating, while visual uniformity says nothing about resistance. Use the product designation, controlled datasheet and agreed electrical test.

Does lower electrical resistance always mean a better semi-conductive tape?

No. The tape must meet the design window rather than achieve the lowest possible number. Mechanical strength, thickness, swelling, compatibility and process stability remain necessary, and the finished cable must satisfy its own electrical requirements.

Can surface resistance replace volume-resistivity data?

No. They describe different current paths and use different units and test arrangements. The cable specification should state which property is required. If a supplier table uses ambiguous terminology, resolve it before comparing grades or issuing a purchase specification.

Can CW-5 replace CW-8 in a semi-conductive layer?

Not on the basis of the published product pages. CW-8 is explicitly described as semi-conductive and publishes resistance data; CW-5 does not publish that classification. Any substitution requires engineering review, current datasheets, samples and finished-cable validation.

What information should be sent with a sample request?

Send the cable cross-section, tape position, electrical classification and limit, dimensions, adjacent materials, application speed and tension, test medium, finished-cable standard and expected order quantity. Ask the supplier to identify the proposed grade and every test method used.

To specify a non conductive water blocking tape or a semi-conductive alternative, send the layer drawing and acceptance criteria to Jiangsu Chaowang New Material. Request the current grade-specific datasheet and a representative sample; if CW-5 or CW-8 is proposed, record the exact grade and verify its electrical function before volume approval.