En-Gauge

Have you ever wondered why XHHW is used in your electrical contracting work as opposed to, say, THHN?  Isn’t THHN cheaper?  Well, yes, it is, but there are several performance advantages to consider when using XHHW that outweigh the cost savings you’d realize from pulling in THHN.

Here are a few of them:

• XHHW-2 is rated up to 90° C in both wet and dry environments.  THHN is rated up to 90° C in dry environments only.  Dual-rated THHN/THWN carries a 75° C wet-environment rating.  The 0.004” nylon jacket on the THHN is hydroscopic (that is, it absorbs moisture), which prohibits its use in wet locations at any temperature.
• XHHW-2 is insulated with cross-linked polyethylene (XLPE), which provides a di-electric constant (k) value usually ranging from 2.2 to 3.0 megohms @ 20° C. This is approximately half the value of the PVC/Nylon combination in the THHN product.  This results in  reduced leakage, which provides superior insulation performance.
• As a thermosetting material, XLP(E) has higher stability in varying temperature environments.  It resists flow at higher temperatures and cracking at lower temperatures better than comparable thermoplastic materials such as the PVC (Polyvinylchloride), which is used in THHN.

XHHW is recommended by the electrical distribution industry for commercial, industrial, and institutional building applications. The National Electrical Code (NEC) Article 310 describes the specific applications and installation for this product.

So, make sure that you have both the right product and the best product for the job. Check the job site conditions and the NEC requirements for them.  Insure your job is “First Class” – it will make life easier for you and the customer down the road!

Think you need XHHW? Check out our Building Wire page for Kris-Tech’s product offerings. We have XHHW-2 in 10 (ten) colors depending on your needs, and in both solid and stranded constructions.

Need XLPE control or switchboard wiring? Tinned high-flex stranding is available in both SIS and XHHW-2 products.

You can also fill out a quote request using the form on the right, or contact us directly for a copy of our specification sheet or more information

More discussion on Direct Burial/Tracer Wire and why it’s used

We got a comment on one of our blog posts about Direct Burial Wire, and I thought it would be a good opportunity to highlight our response in the form of a blog post.  The original comment/question was:

“Why do you need to install this Tracer Wire? Do we need to install Tracer Wire for metal pipes? Metal pipe is a conductor already. I understand using this for plastic pipes, but metal pipes? How is this tracer wire installed on buried pipes?”

The response from Dave, our President, is the following:

“[We use tracer wire] To locate buried conduits used in one of many applications such as electrical, water, sewer, fiber, and other (that didn’t occur to us).”

Remember the days of calling the guy with a backhoe, two helpers, a pick and a shovel, and starting your work with “I think that it is over here somewhere…”  This usually resulted in a big, unnecessary trench, and probably some damage to either the conduit or the surrounding area. Thankfully, those days are gone.

Modern locating systems use signals, as opposed to voltage, to locate buried metallic and non-metallic conduit.  The system typically consists of a signal transmitter connected to the exposed end of the tracer/locator wire (usually in a switchgear room or an exterior riser), which functions as an antenna.  In electrical applications this eliminates the need for a contractor to employ an expensive crew to de-energize the electrical system to hook on to the buried lines.  Once the electrical hazard is eliminated, an internal or location-for-hire service can be utilized with no risk.

When deciding whether the cost of the locator wire provides an acceptable return, there are some basic considerations, such as:

• What is the cost of a service outage?  Is it reduced through quicker locating?
• What are the costs of my locating crew – backhoe? Crew? Trucks?
• Should the locator wire be expected to have the same lifecycle as the conduit? (Stay away from nylon-coated THHN – you don’t bury nylon pipe for a reason!)
• Can we improve response time with a locating service? Locating is what they do; they may have recommendations!

How are these locator systems installed?  Depending on your circumstances, the locator wire may be laid in a trench above the conduit, pulled in with a trenches machine, or installed via directional drilling.  Only the end user is aware of the job site and system conditions that determine the method. Different types and sizes of wire apply to each specific method of installation.

Direct burial-rated tracer/locator wire provides a reliable, low cost, low risk insurance policy on a utilities plan for its infrastructure life cycle. ”

How “low cost?” Depending on copper costs and conductor size, the typical copper locator/tracer wire may cost between 10 to 20 cents per foot. So this is one insurance policy that’s worth picking up.

Think you need Tracer Wire? Check out our Utilities & Municipalities page for Kris-Tech’s product offerings, You can also fill out a quote request online, or contact us directly for a copy of our specification sheet or more information.

Looking for our solar products?  Visit our USE-2 Solar Wire page and our Photovoltaic (PV) Wire page.

Photo Credit: Wayne National Forest

The Underwriters Laboratories (UL) recently put out a brief overview of the solar panel market and the copper wire requirements needed to serve that industry.

We took some time to brush up on the current standards for our own PV wire products, and the distinction between PV wire and USE-2 wire in photovoltaic modules.  We thought you might be interested.

In summary, UL says “PV wire has superior sunlight resistance and low-temperature flexibility in addition to a thicker insulation or jacket and a proven level of flame resistance.”

Overall, only wires or cables highlighted in the National Electric Code (NEC) can be installed in modules that will be sold in the US.

Requirements for North American PV module interconnecting wires

• Single-conductor Type USE-2 cable and photovoltaic (PV) wire are both ok to use in exposed outdoor installations.
• Because these installations are usually found in more extreme environmental conditions, the insulation for these conductors must be sunlight resistant and rated for wet conditions, and must be able to handle temperatures of up to 90°C.

The main differences between PV wire and USE-2 wire

• USAGE
  • PV wire is solely used for interconnecting PV modules, and was developed to be able to handle 90°C in wet conditions and 150°C in dry conditions.
  • USE-2 wire is usually used for connecting terminals of service equipment, and is mostly found underground, and is therefore only rated to handle 90°C in wet or dry conditions.
  • Both can be UL rated at 600V.  However, PV wire can also be rated 1000V or 2000V if needed.
  • Both wires can be used in grounded PV arrays, but only PV wire can be used in ungrounded ones.

• CONSTRUCTION
  • PV wires have thicker insulation for added protection.
  • USE-2 is often used in places that don’t require a high level of movement out of the wire, and can therefore be made out of either stranded or solid conductors.
  • However, since PV wire is used only in solar panels, it needs to be flexible, so is only made from stranded wires.
  • The smallest size available for USE-2 wire is 14 AWG, however PV can get as small as 18 AWG.

• TESTING
  • PV wires must go through a flame test, USE-2 does not (since it isn’t usually installed in places where flames would be found). On the other hand, USE-2 must go through various abuse tests that PV wires aren’t subject to.
  • PV wire must go through more strict sunlight resistant tests.
  • Both of these tests are part of the UL 4703 specification requirements.

You can find out more about the solar market on the first page of the report, “Designing UL Compliant Photovoltaic Wire” (.pdf format).