High Voltage FAQs



Kerite FAQs

Kerite Essentials

Q: Where is your cable manufactured?

A: Kerite cable is manufactured in Seymour, CT and has been since 1854.

Q: Does Kerite have office/project in Canada?

A: Kerite does not have an office in Canada.  However, we have done projects in Canada.  Please contact Kerite with details regarding the specific installation you are referring to, and we will gladly discuss the project in more detail.

Engineering and Manufacturing

Q: If you recall each project had a “specific” cable designed for it. Assuming on one conductor is affected by a failure (dig in, car pole, termination failure, etc.) the “Hot Spare” would allow for the transmission segment to continue operating until a replacement cable can be manufactured. If a hot spare was not included in the design the question would then become: How quickly can Kerite manufacture a replacement cable assuming “normal” production of prior orders at the factory?

A: Our typical lead time is 10 – 12 weeks.  However, depending on the type of cable, we may have something in stock that could substantially shorten the lead time.

Q: Can you make a higher voltage stress design using a smaller insulation for 115kV? Would also like to see the cable be more flexible (minimum bend radius) for retrofit into existing smaller 4" duct?

A: We can construct reduced diameter cables for special projects.  Please contact Kerite to discuss your specific project.

Q: What is the reel length of 138 kV cable when 795MCM?

A: Kerite manufactures 750 MCM 138kV cable and there is 3400’ on a reel.

Q: Does Kerite produce corrugated metallic sheath?

A: Kerite uses an optional copper tape underneath the jacket. 

Q: Do you prefer to deliver on steel drums or on wooden drums?

A: Kerite usually delivers on steel drums.  However for shorter lengths or smaller cables, we have used wood.

Q: Do you produce to IEC Standards? Are there any specific to EPR insulation?

A: Kerite produces to ICEA Standards and have not done formal testing to IEC standards.

Q: What distances are the limitation, if any?

A: Cable length is a function of conductor size, operating voltage, and ampacity.  Please contact Kerite to discuss the specific application.

Q: You can save on civil costs with Kerite cable because you don't need a lead barrier to keep out water, right? I believe the bending radii can be reduced with Kerite without the lead barrier, thus saving money.

A: You are correct.  Eliminating lead is also an environmental plus.  However, Kerite does not believe that the bending radius is affected by the lead.  The cable diameter determines the bending radius.  If you need additional detail, I can have one of our engineers reach out to you.

Q: Do you provide covered conductor for low and medium voltages?

A: Kerite manufactures MV cable for 5kV to 46kV and it is a covered conductor.

Q: To what voltage level does Kerite produce cable - 115kV, 230kV, 500kV?

A: Kerite High Voltage Underground Transmission cable is manufactured from 69kV up to 138 kV.  Our specialty cables (like subsea) goes up to 35 kV.

Q: Do you do pipe type cable?

A: Yes we do!  We have done many projects replacing PILC with standard Kerite cable.

Q: Can an air switch open a line segment with a Kerite Cable?

A: Yes

Q: Do you supply temporary jumper cables?

A: We make portable HV cables. Contact Kerite to discuss specifics or to get a quote if you’re working on a particular project.

Q: Do you recommend any special protection schemes to protect the cable, such as not reclosing on a fault? Or can it be treated as a normal part of an overhead line (in the situation of a crossing dip to get under another line)?

A: No special treatment is required.


Q: What determines the cable accessories manufacturer or technology you use to terminate and splice Kerite HV cables on a project?

A: Customer preference dictates which termination or splice manufacturer we use.

Q: Does Kerite manufacture its own splices and terminators?

A: No, Kerite does not manufacture our own splices and terminations.  We have several manufacturer partners who do this.

Q: Are the transmission rated terminations pre-molded or taped?

A: The terminations are pre-molded.


Q: Do any of your cable pulls involve external lubricants? What software do you use to do cable pull design?

A: We use Polywater lubricants for our cable pulls.  EPR cable withstands high pulling tensions and no software has been necessary for our installation pulls. 

Q: What type of cable installation is recommended - direct burial or in underground duct banks?

Q: Do you single- point bond?

A: We do recommend single point grounding when we perform an installation.

Q: What is the range of recommended pull lengths (in duct bank)?

Q: How could Kerite be cost effective of performing the construction works in case of remote projects, let’s say in Canada? Do you have special ways of mobilization for your equipment?

A: We utilize local subcontractors for civil work, and do the termination and installation ourselves. We completed a wind farm project in Canada last year.

Q: Do you have any ANTI-Theft ideas to pass along?

A: Since our cable is underground, we do not experience theft.  We have had utilities that painted their above ground copper wire blue in substations to prevent theft.

Q: What is the relation between the installation costs of OHL and underground cables?

A: We do not conduct OHL installations and do not feel qualified to answer this question.

Q: Do you also apply horizontal directional drilling for cable installation?

A: Yes we do.

Q: Do you conduct turnkey projects outside the US?

A: Yes - we do international installations.  Please contact Kerite to discuss the project in more detail.

Q: Regarding the Civil Construction, do you consider that it is better to be In-house instead of Outsourced?

A: If you outsource the civil, you get the exact outcome you require, which results in a much more efficient project.

Q: Can regular underground cable be used for shallow (10-20ft) water way installations. Example if the system L-L voltage is 12kV, can 35kV cable be used in such applications?

A: Yes – regular underground cable can be used for shallow water installation.  A layer of armor wire is frequently added for physical protection.  35 kV cable is often used in these applications.  Please contact to discuss the project.

Q: Is each cable within its own conduit (6" or 8") or are there 3 within a single conduit?

A: Each cable is in its own conduit.

Q: Do you recommend pulling a 4th - hot-spare on these projects?

A: Some utilities have a policy to pull a fourth as a spare.  Some do not. We accommodate both types of requests.

Q: Do different cable insulation configurations require different stress relief terminators?

A: We prefer to use G&W terminations. Final decisions regarding termination types are made by the utility.

Features & Benefits

Q: What is the maximum high voltage of your cable?

A: Kerite maximum voltage is 138kV.

Q: To what voltage level does Kerite supply cable?

A: 138 kV

Q: What are the benefits of the conductor shield for HV cable?

A: The conductor shield reduces stress on the insulation layer.

Q: How does your cable's flexibility compare to other EPR cables?

A: We can only comment on our own product.  Kerite HV cable has a minimum bending radius that should not be less than 12 times the outer diameter of the cable.

Q: Ground temperature in some countries can be around 35 deg c

A: Kerite cable can operate up to 90 degrees Celsius. 35 degrees should not be an issue.

Q: How can we handle the high temperature of underground cables?

A: Kerite cable is designed to operate at 90 degrees Celsius with higher temperatures for specific periods of time. Please contact Kerite with specifics on the application.


Q: What are the advantages of EPR over XLPE? We would be installing single phase cable in conduit.

A: Please click the link to read the “Five Reasons” document that will explain the advantages of EPR.

Q: Other than preventing water ingress, what are the other benefits of EPR vs TS-XLPE?

A: Kerite EPR is discharge resistant vs. discharge free, delivers superior transient attenuation, and has the longest service life in the cable industry.

Q: Can you explain EPR cables?

A: Please refer to this link on our website:

Q: What is the major difference between EPR & XLPE insulation? Why is EPR preferred?

A: The major difference is the material makeup.  We feel that EPR is superior because of its wet performance, flexibility, and long service life.

Q: Does the jacket provide protection from moisture ingress?

A: Technically, no.  Jackets are designed to prevent physical damage to the cable and its components. Kerite’s EPR insulation does provide superior water protection.

Q: EPR can be run at a higher temp that XLPE?

A: Both EPR and XLPE should only be run at their maximum rated temperatures.  If you have a specific application, please contact Kerite to discuss your specific application.

Q: What about maintenance costs or requirements?

A: There are no maintenance costs for EPR cables.

Q: Why does EPR have superior water performance other cable insulation?

A: It is an inherent property of the EPR insulation itself.

Q: Can EPR be 105 C rated?

A: EPR Cable has been tested to operate up to 105 degrees Celsius. The accessories have not been certified by their manufacturers to operate at that temperature.


Q: Do you recommend a HIPOT test to the system (cable-connectors) according with IEEE-400?

A: We do recommend this test upon initial installation.

Q: In commissioning test, do you recommend the 24 hours voltage test at nominal voltage or do you prefer to increase the voltage level for the test?

A: Many of our clients prefer the 24 hour nominal voltage test.  We generally let them specify how they would like the cable tested.

Q: Do you prefer the use of partial discharge monitoring or temperature monitoring?

A: We recommend temperature monitoring.

Q: What type of proof testing do you recommend to commission a new cable installation? AC vs. DC

A: We conduct a DC-HIPOT test at installation.

Q: Do you recommend VLF / tan delta testing for maintenance purposes?

A: We do not recommend this type of testing. Kerite HV cable has not experienced a need for field testing.

Q: Can a Partial Discharge test be performed on Kerite Cable?

A: Yes, it can.

Q: Can you give us additional information about the failure statistics and the life cycle of other cables?

A: Kerite is unaware of any field failures, so we have no logged statistics about cable failure.

Q: Do you see an advantage in using Low Frequency AC testing over DC HiPot testing?

A: We don’t conduct Low Frequency AC testing.  If you would like to discuss this further, I can have an engineer contact you. Please provide a contact number.

Q: What type of post-installation do you perform on turnkey projects in order to certify your installation?

A: Kerite does several post installation tests to verify that the installation is correct.  Please let me know if you have additional questions regarding a specific installation.

Subsea Cable

Q: Does subsea cable have a conductor ampacity derating similar to duct/conduit?

A: A  de-rating does not apply to subsea cable because of the thermal transfer produced by water.


Q: You mentioned that Kerite warrantees their cables for their entire installed life. Can you explain what that means? For instance, will Kerite replace cables that fail?

A: It means that Kerite will warranty its HV cable for as long as the circuit is energized – the life of the installation. If you have a situation where you believe a Kerite cable has failed, we would perform tests to determine the cause of the failure. Historically, we have never experienced a High voltage cable failure that was actually caused by the cable (the termination was done incorrectly, or the cable was not grounded correctly, for example).

Q: What about the durability of your cables?

A: Kerite cable is guaranteed for the lifetime of the installation.

Q: Don't all HV cable manufacturers insist on installing and terminating their cable to maintain warranty?

A: We can only answer for Kerite, and we do require our own installers for the installation for our cable. Our cable is warrantied for the life of the installation.

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