Module leads (USE-2) need to be in conduit

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michigan
I have an inspector telling me that the USE-2 leads off the modules need to be in a conduit for a ground mounted array. Is this true and if it is, what are other installers doing in this case. I have suggested using LTFMC in some way.

Thanks,
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
USE-2 is good for underground but once it is above ground it must be protected from damage. Is that what you are getting at?
 
Location
michigan
use 2

use 2

PV modules as far as I know only come with USE-2 leads. 690.31 (A) in the NEC 2008 hand book says: "most PV modules do not have provisions for attaching raceways. These circuits may have to be made "not readily accessible" by use of physical barriers such as wire screening."

If that is the case, why does Manufactures of PV Modules design the modules with the USE-2 cable for their leads (rhetorical ?)? As stated above by NEC handbook, you can wire screening around it. But you attach the wire screening directly to the PV module then you have voided the warranty. It may not be feasible to attach the wire screening to the racking.

I've been installing solar PV and thermal for over seven years. The inspector wants me to put a fence around the arrays to protect the public. It's hard to make PV affordable in most states as it is.

I hope I don't sound like I am ranting. I need a good solution to this problem to avoid putting the fencing up. Like I said, I am trying to figure a way to use LTFMC over the USE-2 cable to protect, while still being able to get at the M4 connectors if needed and not voiding the module warranty.

Thanks again
 
Location
michigan
thats the good thing about forums

thats the good thing about forums

thats the good thing about forums is that you can bounce ideas around and we all hopefully learn something and become better at our craft.
 

iwire

Moderator
Staff member
Location
Massachusetts
For the purposes of PV installs USE can be run exposed.


IV. Wiring Methods


690.31 Methods Permitted.


(B) Single-Conductor Cable.
Single-conductor cable type
USE-2, and single-conductor cable listed and labeled as
photovoltaic (PV) wire shall be permitted in exposed outdoor
locations in photovoltaic source circuits for photovoltaic
module interconnections within the photovoltaic array.

Exception: Raceways shall be used when required by
690.31(A).

But notice the exception (seems like the opposite of an exception :blink:)

690.31 Methods Permitted.

(A) Wiring Systems.
All raceway and cable wiring methods
included in this Code and other wiring systems and
fittings specifically intended and identified for use on photovoltaic
arrays shall be permitted. Where wiring devices
with integral enclosures are used, sufficient length of cable
shall be provided to facilitate replacement.

Where photovoltaic source and output circuits operating
at maximum system voltages greater than 30 volts are installed
in readily accessible locations, circuit conductors
shall be installed in a raceway.
In my opinion a ground mounted array, unless fenced in would be a readily accessible location and require the USE to be run in a raceway.
 
Location
michigan
I agree IWIRE

I agree IWIRE

"In my opinion a ground mounted array, unless fenced in would be a readily accessible location and require the USE to be run in a raceway."

I agree with that and I think that has been established. What I am trying to find out is what other installers are doing/using to protect the wires besides putting up fences.

There is a picture in this article of what one company has done:http://solarprofessional.com/a...e=SP2_4_pg48_Brearley

t
here has to be better methods out there of protecting the wires and public than putting a fences up. I think in the link above is a good example of it.

Thank you for input on this.

This is a great forum
 

Zee

Senior Member
Location
CA
HOToff theplate,

Yeah, I hear you. Same issue hear: many years of experience, yet this is not resolved IN PRACTICE!
Fences basically are only solution i have seen so far.

BUT most installs (read 99%) simply get away with it because of inspector naivety.

Conduit between all mod.s???
Fences?? Yeah..... add $$$$.

A thread titled Protecting conductors on ground mounted arrays (about 3 pages back) might help you.

Yet, even after aforementioned thread, I still remain curious , as you are, on how people are complying.

I think the lack of answers indicates: my experience: installations simply do not comply.

There's money to be made with a good product / solution....
 

Zee

Senior Member
Location
CA
That said, you sure it's USE-2 on the modules, and not PV wire? If so, kinda cheap of mfctr.
Nearly all modules i work with are PV Wire equipped.
 

Zee

Senior Member
Location
CA
add'l idea: any chance the inspector would be satisfied with PV wire?
I am not sure it meets Code, but it is pretty robust. Double jacketed.
I checked out the link to the photo of wire managemnent under an array in Solar Pro. Thanks.
 
Location
michigan
Zee

Zee

The last I checked, SunPower, Mage and Sanyo all use the USE-2 wire for cabling. It is UL listed as such. I will check again though.

Good to see you on this and Solar Pro forum. If you do solar thermal Heatinghelp.com is a good one.

Thanks for the thought.
 

iwire

Moderator
Staff member
Location
Massachusetts
I agree with that and I think that has been established.
I thought that you had asked if it was true? :huh:

I have an inspector telling me that the USE-2 leads off the modules need to be in a conduit for a ground mounted array. Is this true and if it is, what are other installers doing in this case. I have suggested using LTFMC in some way.
As far as what to do about it run a raceway, it is not imposable.

Dealing with the whips out of the modules could be an issue but I believe some brands can be ordered set up for a flexible raceway connection.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Not sure what happened to my previous reply to this thread...

Sharp has modules that are available with PV wire leads. Probably some others as well. But it makes no difference to the code requirements under discussion here.

I do not believe the intent of 690.31.(A) was to prohibit ground mounts that aren't fenced. But unless the code is revised, or unless better products are made available that enclose DC conductors, that is what the language currently amounts to. Meanwhile, I've certainly worked on millions of dollars worth of systems where this wasn't enforced, and I highly doubt that there is a system anywhere where installers have put module leads and connectors in raceways. So as for what the industry is doing, the answer is not much. The closest I've seen is to put a piece of strut along the underside of the array to contain home runs (but not module leads).

I will just note in conclusion that this isn't a matter of electrical engineering or protection of qualified individuals working on systems. It is basically a matter of how much babysitting we think the general public needs to protect them from higher voltage wires. In my opinion, while there needs to be some protection, prohibiting ground mounts without fences is overkill.
 

iwire

Moderator
Staff member
Location
Massachusetts
The last I checked, SunPower, Mage and Sanyo all use the USE-2 wire for cabling. It is UL listed as such. I will check again though.

Good to see you on this and Solar Pro forum. If you do solar thermal Heatinghelp.com is a good one.

Thanks for the thought.
Yes USE can be used, but you still have to follow the code rules in post 6
 

Zee

Senior Member
Location
CA
Jaggedben:
Yes, I agree, PV wire definitely does not equate to conduit, but it does allow me to sleep easier..... :) (The inspector may simply say ok to it. It is a level of protection above USE-2.....it still does not meet the letter of the Code)
Good to hear your experience also with the lack of enforcement on groundmounts, Jaggedben. I don't see this groundmount fencing or inaccessibility provision enforced often. Which means never. All the more frustrating when it DOES come up. Say...when you are done building!

The more i talk about this groundmount accessibility issue vs 600VDC issue the more I see a possible solution:
an expanded metal screen (mesh).
Made of alumium.
NO disimilar metals. NO UV degradation of cheap plastic.
It could be TEK screwed to the underside of aluminum rails. This would be underneath ALL wiring. That would cover 80% of the underside of an array! THen maybe an ACME wire clip could slide onto the lip of the module frame at the array edges, and attach the mesh! Anyways.....wouldn't even be visible.
Am i gonna do this? NO. BUt thinking.......

Hot off the plate: Thanks, the fact that Sunpower has use-2 cabling is prob'ly why i never see use-2 module leads......

 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
You know, when I look again at 690.31(A), what irks me is that it applies to anything over 30 volts. I mean, why couldn't that be raised to 50V, so that micro-inverter systems are exempt? Okay, thanks for letting step on the soapbox.
 

Zee

Senior Member
Location
CA
Maybe b/c code changes are adopted at "DMV pace"........

BUt hold on, the V-ac is well over 50 V..... it is 240 Vac!

Do you mean just the DC module leads would not have to be in conduit then?

I think a groundmount is the ONLY place i would put a micro! That way i can walk up to it and reach under the array when i go to replace......
 
I have an inspector telling me that the USE-2 leads off the modules need to be in a conduit for a ground mounted array. Is this true and if it is, what are other installers doing in this case. I have suggested using LTFMC in some way.

Thanks,
It makes me wonder why the PV manufacturers are not required to install a plain, weatherproof JB with terminals so the interconnecting field installation can be accomplished according to standard wiring practice.
 

BillK-AZ

Senior Member
Location
Mesa Arizona
It makes me wonder why the PV manufacturers are not required to install a plain, weatherproof JB with terminals so the interconnecting field installation can be accomplished according to standard wiring practice.
Lots of reasons:

Because 99% of the modules will be used in situations where the plugs are a better answer. The only failures I have seen in PV wiring at the module level have been in junction boxes due to loose connections or water entry.

Some manufacturers offer junction boxes at extra cost, mostly on smaller PV modules.

One code problem with junction boxes on modules is that you must use metal conduit due to temperatures over 75?C. Most PV modules with junction boxes do not have a deep enough box such that a straight conduit will clear the frame, requiring labor intensive offsets. Then there is the problem of supporting the conduit between modules. If the circuit is over 250 volts, the conduit must be bonded, another cost element. Deep junction boxes do not allow the close stacking on modules for shipping that is now common, adding to the cost of shipping.
 

iwire

Moderator
Staff member
Location
Massachusetts
It makes me wonder why the PV manufacturers are not required to install a plain, weatherproof JB with terminals so the interconnecting field installation can be accomplished according to standard wiring practice.
As far as I know at least some manufacturers offer that option but it has to be asked for.
 
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