FAQS Bubbles

RLH Industries, Inc. is a world leader in fiber optic link products and installation services for the telecommunications industry. With engineering and manufacturing in Orange, California, USA, and distribution across North America and internationally, RLH Industries has been designing, manufacturing, and installing fiber optic solutions since 1988. RLH is recognized as an innovator in the fiber optics industry, and has pioneered solutions for High Voltage Isolation, PCS, and Critical Communications applications just to name a few.

Sales & Business Questions

How do I buy products from RLH?

At RLH we sell our products and services directly to end users. This helps to ensure our customers are getting the best and most appropriate solution available.

Alternatively, some customers may wish to work through a distributor as part of their procurement strategy, RLH is already a supplier to most major distributors in the United States and we are glad to work with both you and your preferred distributor.

From where do RLH products ship?

All RLH products ship from our warehouse and manufacturing facilities located in Orange County, California unless specifically noted otherwise.

Where are the products made?

We take pride in the fact that a majority of our products are designed, engineered, and manufactured right here in Orange County, California. We have been located here for over 35 years and we have partnered with many local businesses that continue to help us to deliver high quality products across the globe.

What is RLH's return policy?

For newly shipped standard items: There is a 30-day money back return guarantee offered, with an extended return period of up to 60 days, less a 25% restocking fee. After 60 days, returns are not accepted. All return shipping costs are responsibility of the customer.

  • Returned goods must be in new condition otherwise they may be subject to a restocking fee regardless of when the return was initiated.

Products not covered under RLH’s standard return policy:

  • These items are non-cancellable and non-returnable, non-standard items may include but are not limited to:
    • Custom Cabinets & Pedestals
    • Custom Fiber Cable Assemblies
    • Non-Stocked / Specialized Fiber Cable o Customized Electronic Devices
  • Products offered from other manufacturers for resale are subject to the original manufactures or distributors return policy.

All returns must be accompanied by an RLH issued RMA number matching the part number being returned. The shipping box should be labeled as directed in the RMA return instructions. RLH is not responsible for lost returned merchandise not accompanied by an issued RMA# and identified appropriately.

Except where a specific contract provides otherwise, these terms apply to all equipment orders. Please contact RLH with any questions for return information on specific products prior to purchase.

Warranty returns

Please see the product data sheet or user guide for the length of the product’s warranty and the link to the general policy.

Where is RLH located?

All of RLH’s offices are located in Orange County, California, USA.

What is RLH's warranty policy?

Please see the product data sheet or user guide for the length of the product’s warranty. The general policy can be found on the warranty page.

How long has RLH been in business?

RLH Industries, Inc. was founded in 1988, by Robert L. Harris.

35+ years of Excellence

High-Voltage Isolation Questions

What is Ground Potential Rise (GPR)?

Also known as Earth Potential Rise (EPR), this occurs when a large amount of electrical current flows to Earth. Typical scenarios would be a lightning strike or more commonly a ground fault at a high voltage facility. The point where the current enters the earth will have highest potential, and that potential declines with distance away from the source. This is a typical concern for electrical substations or power generating facilities because a high potential can be a hazard to people and equipment.

What is GPR zone of influence?

In North America the Zone of Influence is typically called the “300 Volt Point”. When a GPR Event occurs the Voltage declines the further away from the event you get, the 300 Volt Point would be the distance away from the event where the ground Voltage is less than 300 Volts. The zone of influence is the area around the event where voltages exceed 300 Volts. It’s not always a spherical shape as grounding structures and soil resistivity can change within the area as shown by the illustration below.

GPR Zone of Influence
GPR Zone of Influence

RLH Offers GPR Studies which help determine the zone of influence and 300 volt point needed by many telecommunication companies to demark their equipment and provided isolation into the High Voltage Facility.

Why is high-voltage isolation equipment needed?

High Voltage Isolation Equipment removes the copper conductor (typical telecommunication wiring) from GPR event prone facilities. RLH Pioneered using all dielectric non-conductive fiber optic cable to transport copper based telecommunication signals into high voltage facilities. By using Dielectric cable we provide fail-safe protection from GPR events, which ultimately protects people and electronics.

See further examples in our video “Failure to Communicate“.

What are the high-voltage protection policies of my local telecom providers?

AT&T, Verizon, Frontier, and Century Link all have different policies when it comes to isolating of telecommunication circuits into high voltage areas.

In general each will require high voltage isolation equipment to be located a certain distanced away from the high voltage facility. Sometimes they will require a certain amount of distance or they may require equipment to be located at a certain volt point (see Zone of Influence).

Each region is different and we encourage you to work with your territory account manager to help identify the proper and accepted isolation configuration needed in your region.

Fiber Optics & Fiber Cable Questions

What's the difference between singlemode and multimode fiber?
Singlemode Multimode
9 Micron Core 62.5 Micron (most common)
Longer Distances Shorter Distances
Lower Cost Fiber Higher Cost Fiber
Higher Cost Electronics Lower Cost Electronics
Great for backhaul and premise to premise applications Great for in building / High bandwidth backbone designs


Optical Fiber Core Diameters
Optical Fiber Core Diameters
What's the difference between OM1, OM2, and OM3 fiber?
Designation Core Size Type
OM1 62.5 Micron Core Multimode – standard multimode cable
OM2 50 Micron Core Higher bandwidth than OM1
OM3 62.5 Micron Core (*laser optimized) Commonly called 10gig; higher bandwidth than OM1 & OM2

*RLH Fiber Link Card and DIN Multimode electronics are compatible with OM1, OM2, & OM3 multimode fiber.

What's the difference between Riser- and Plenum-rated fiber cable?

Plenum Rated Cable is the more expensive choice and is for use in plenum spaces. Plenum spaces are those that may allow fire and smoke to travel more freely. For instance heating and cooling ducts or underneath raised flooring. Plenum cable has special jacketing that when ignited provides less toxic smoke.

Riser Rated Cable is the less expensive option of the two, it doesn’t meet the stricter requirements that plenum rated cables do, however not all projects and installations require the use of plenum cable. It’s important to know which will be needed for any installation for regulatory as well as budgetary purposes.

Do I need singlemode or multimode fiber optics?
Singlemode Optics Multimode Optics
More expensive due to stricter requirements of the small core size of singlemode fiber cable Less expensive due to the larger core size of multimode fiber cable
Singlemode fiber cable is generally less expensive Multimode fiber cable is generally more expensive
Singlemode optics can be used for distances exceeding 60 miles Multimode fiber optics doesn’t typically exceed 1.5 miles
Singlemode Optics may be compatible with multimode fiber cable Multimode optics are not compatible with singlemode fiber cable
What are the most common fiber connector types and what do they look like?
Connector Types - ST
Connector Types - SC
Connector Types - LC
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