PV wire voltage rating

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
Noticed this today and find it a bit odd. I included two samples because the wording is slightly different. When does the 600V rating apply? It seems that when used as USE-2, the 600V rating applies which seems to imply that it is 600V when direct buried. However it also says "direct bury" which seems to me to always apply. Because of the wording difference, the 600v could be thought of to apply to the direct bury installation on the black more than on the green. Am I overthinking this?
 

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IMHO you are overthinking.
Because the UL specification for USE-2 does not include any testing method for voltages over 600V you cannot apply more than 600V when your conditions of use allow USE-2 but do not allow PV wire.
The PV wire specification includes testing up to 2kV, so anywhere that you are allowed to use PV wire under the NEC you can apply the rated voltage of 1kV or 2kV.

The direct burial usage is, I believe, only part of USE-2 qualification so you are limited to 600V for that portion of the circuit. :)
 
GoldDigger said:
IMHO you are overthinking.
Because the UL specification for USE-2 does not include any testing method for voltages over 600V you cannot apply more than 600V when your conditions of use allow USE-2 but do not allow PV wire.
The PV wire specification includes testing up to 2kV, so anywhere that you are allowed to use PV wire under the NEC you can apply the rated voltage of 1kV or 2kV.

The direct burial usage is, I believe, only part of USE-2 qualification so you are limited to 600V for that portion of the circuit. :)
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Ok, but here is my train of thought:

1. The wire is also rated RHW-2, so I believe I can use it at 2kv outside of PV systems.
2. Under what conditions would one "only be using the wire as" USE-2?
3. I think a conductor or cable can be rated for direct burial separate from the USE classification. For example tray cable I have used is rated for direct bury. USE is of course rated for direct bury by definition, so it seems to me since they wrote "direct bury" on it, it is ok for direct bury outside of article 338.
 
I think what's going on here is that the manufacturer wants their product in the running when you call up your distributor and ask for some USE-2, in case that's what some designer or engineer specified on your plans and/or got approved by the AHJ. I also can't think of a situation where it could be used as USE-2 and not one of the others. I can, maybe, imagine a situation where having the marking saves some hassle with an inspector and/or plan revision.
 
electrofelon said:
2. Under what conditions would one "only be using the wire as" USE-2?
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When it is direct buried.

3. I think a conductor or cable can be rated for direct burial separate from the USE classification.
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I do not believe you will find RHW to be rated for direct burial.


For example tray cable I have used is rated for direct bury. USE is of course rated for direct bury by definition, so it seems to me since they wrote "direct bury" on it, it is ok for direct bury outside of article 338.
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I think that is a stretch.

What code articles apply when using RHW outside a raceway?
 
electrofelon said:
I hypothesize that "direct bury" can be an "adder" like "sun-res" appears to be. Foe example, this pv wire is rated for direct burial but does not appear to be use-2:

http://www.southwire.com/products/renew-2kv-copper-pv-wire.htm
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I'm skeptical that you are limited to just 600V, simply because you are directly burying it. Check with the manufacturer to confirm. However, what would be the point of "600V" appearing anywhere within the print legend, if the 1kV/2kV rating applies universally to all applications?

Also, I'd like to know what exactly the slash rating of 1kV/2kV means? Is it a volts-to-ground (1kV) verses volts line-to-line (2kV) rating? Is there any voltage configuration greater than 1000V (but less than 2000V), that I should second-guess myself on assuming that the 2kV rating applies?

I would think if 2kV is the rating of the insulation no matter what the situation, then that would automatically be inclusive of 1kV and 600V, and there would be no reason for the lower ratings to appear in the specification. Other than to improve the ability to find the product in a search.
 
electrofelon said:
I hypothesize that "direct bury" can be an "adder" like "sun-res" appears to be. Foe example, this pv wire is rated for direct burial but does not appear to be use-2:

http://www.southwire.com/products/renew-2kv-copper-pv-wire.htm
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You can hypothesize all you want, but it ultimately comes down to the UL listing conditions for the wire. If there is no applicable UL standard for the wire that applies over the full range of conditions described in the listing standard there is no way to determine that the qualification (direct bury) is justified.

There is no recognized way to test a particular sample of PV wire to determine whether it is can withstand direct burial or not, so you cannot simply assert that additional property as an adder. You have to specify a UL wire type that contains such a testing procedure.
 
GoldDigger said:
You can hypothesize all you want, but it ultimately comes down to the UL listing conditions for the wire. If there is no applicable UL standard for the wire that applies over the full range of conditions described in the listing standard there is no way to determine that the qualification (direct bury) is justified.

There is no recognized way to test a particular sample of PV wire to determine whether it is can withstand direct burial or not, so you cannot simply assert that additional property as an adder. You have to specify a UL wire type that contains such a testing procedure.
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That doesn't make any sense. There is a way to test a USE-2 wire at 600V for the direct burial application, and there is a way to test PV wire at 1kV/2kV for other locations (conduit, free air, etc).

So why is it not possible to do the combine these tests for direct burial, and apply the 1kV/2kV test voltages?
 
Carultch said:
That doesn't make any sense. There is a way to test a USE-2 wire at 600V for the direct burial application, and there is a way to test PV wire at 1kV/2kV for other locations (conduit, free air, etc).

So why is it not possible to do the combine these tests for direct burial, and apply the 1kV/2kV test voltages?
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1. If the tests in question are not part of the same UL standard as the rest of the tests of the wire, then they cannot be applied as an "extra" to wire tested under one overall standard.
2. The NEC specifies by UL wire type alone what conditions of use are allowed or prohibited for that wire. For better or for worse there is no UL language that allows you to change those use conditions on the basis of an "add-on" qualification.
3. Among other things, that is why the PV wire type had to be created instead of adding additional qualifications to an existing wire type.
4. The CMPs and historic practice allow you to choose which wire type you are going to apply for code purposes in a given situation when a wire has multiple type listings, but you cannot mix and match parts of those conditions to cover one segment of wire.
 
Is there no direct burial as part of the standard for PV wire? I swear at some point I've heard of such a wire. What about the RHW-2 standard?
 
GoldDigger said:
Because the UL specification for USE-2 does not include any testing method for voltages over 600V
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I agree. The USE standard (UL 854) only goes up to 600V. However note that the RHW standard (UL 44), does go above 600 volts so it seems that I may be able to use the 2kv cable at 2kv for non pv applications.

GoldDigger said:
The direct burial usage is, I believe, only part of USE-2 qualification so you are limited to 600V for that portion of the circuit. :)
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jaggedben said:
Is there no direct burial as part of the standard for PV wire? I swear at some point I've heard of such a wire. What about the RHW-2 standard?
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iwire said:
I do not believe you will find RHW to be rated for direct burial.
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The UL standards, 854, 44, 4703 that apply do these types are not publicly available and must be purchased so it is hard to say for sure. It does seem that PV wire and RHW are not suitable for direct bury based on what tidbits I could find. I am still holding on to my "direct bury adder" idea a bit though. Take a look at this cable. It states direct bury but does not mention The USE standard (UL 854).
http://www.adcable.com/images/renewable_catalog/ADC_2KV_Dual_Pass_PV.pdf

Carultch said:
Also, I'd like to know what exactly the slash rating of 1kV/2kV means? Is it a volts-to-ground (1kV) verses volts line-to-line (2kV) rating? Is there any voltage configuration greater than 1000V (but less than 2000V), that I should second-guess myself on assuming that the 2kV rating applies?

I would think if 2kV is the rating of the insulation no matter what the situation, then that would automatically be inclusive of 1kV and 600V, and there would be no reason for the lower ratings to appear in the specification. Other than to improve the ability to find the product in a search.
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I have wondered about that slash rating too. The PV wire standard, UL 4703, categorizes them into 600, 1000, and 2000 volts, so my guess is they are just being complete and saying the 2kv meets all of them, even though it seems unnecessarily obvious to note that if it is rated for 2kv, it is also rated for 1kv.
 
GoldDigger hit the nail on the head, it's a UL listing requirement that drives the different voltage ratings. So don't over think it. The manufacturers wants to sell all the conductor they can so multi-rating is fairly common.
 
electrofelon said:
The UL standards, 854, 44, 4703 that apply do these types are not publicly available and must be purchased so it is hard to say for sure. It does seem that PV wire and RHW are not suitable for direct bury based on what tidbits I could find. I am still holding on to my "direct bury adder" idea a bit though. Take a look at this cable. It states direct bury but does not mention The USE standard (UL 854).
http://www.adcable.com/images/renewable_catalog/ADC_2KV_Dual_Pass_PV.pdf
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You avoided my question, if you are correct what code article applies to direct buried RHW?
 
iwire said:
You avoided my question, if you are correct what code article applies to direct buried RHW?
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I hadnt noticed your last response. I dug up the thread to post some new information I found. First though, in response to your question, doesnt it come down to 310.10(F) which just says they shall be identified for such use. So, if a conductor meets some UL or other product standard for direct burial, then cant it be direct buried? Is your position that the code must grant us specific permission to direct bury a specific conductor?

This is interesting, its from the IAEI:

Photovoltaic (PV) wire has become more robust and versatile over the last few years. In the 2014 NEC, language was added in 690.81 stating that “PV wire that is listed for direct burial at voltages above 600 volts, but not exceeding 2000 volts, shall be installed in accordance with Table 300.50, Column 1.” Additional changes were made in 300.50(A)(2) for directly buried conductors with insulation types up to 2000 volts: “In industrial establishments … nonshielded single-conductor cables with insulation types up to 2000 volts that are listed for direct burial shall be permitted to be directly buried.” In the U.S., the only nonshielded single conductor listed for both 2000 volts and direct burial is PV wire. This type of wire is often used from the combiner to the inverter in large-scale ground-mount photovoltaic installations that are not accessible to the public.

PV wire is listed under Outline of Investigation UL 4703. UL 4703 is currently undergoing evaluation in UL Standards Technical Panel (STP) 4703, and will become a full standard when all required steps are completed. The added code language means that 2000 volt PV wire that is listed for direct burial is now explicitly recognized by the code and requires no additional physical protection other than the minimum cover requirements in Table 300.50.
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