Strain relief

[EW Zuber]

I bought MC4 wires for an installation and found out that the NEC code now requires heavier insulation now and the wires do not fit in the two hole 1/2" KO strain reliefs.
With all the Midnite KO being 1/2" I can not use the 3/4" two hole strain reliefs that are made to accommodate the new wire size.
Wondering what other installers are doing about this?

[Vic]

Hi EW Z..,

Do not know your exact situation.

You probably have RHW-2 cable that may be rated to 2 kV.  You probably do not need this rating.   If this installation will be Inspected,  the Authority doing the inspection should have guidelines on that they are looking for.

This link has a bit of information on some PV cable with a reference to MN strain reliefs:
https://www.solar-electric.com/insulated-outdoor-pv-listed-wire-per-foot.html

IIRC,  #10 AWG RHW-2 cable is about 0.300"  OD,  which seems like overkill for most PV string voltages below about 300 VDC.  Am not an expert on the latest NEC PV requirements.

FWIW,   Vic

[EW Zuber]

Thanks Vic, thats good info at that link.
Seems I need to find an alternative to using these strain reliefs.

[Vic]

EW Z..,

Assume that this MN box is exposed to the weather,  correct?

What is the model number of the MN box that you are using?

You might ping MN Tech Support,  for guidance.

If this system will be inspected,  the AHJ (the inspection Authority)  should be able to help you in ways to use the cable that you have,  and tell you if that large diameter PV cable is required.

The more standard PV cable,  at least what was permitted several years ago often is XLP,  and does not have that additional PVC jacket,  and is customarily rated at 600 V,  perhaps this is the cable that you were planning on using ...

In past Code revisions,  it was permitted to remove the outer PVC jacket of RHW cable,  when it is inside conduit or otherwise protected from direct exposure to elements (as inside a conduit box,  etc).  But,  am certain that you could not strip the PVC jacket at the point where the cable enters the relief.

It is possible that you would be permitted to enlarge the 1/2" KOs to 3/4" with a punch or holesaw,  and use the 3/4" reliefs,  particularly,  if there are not too many 3/4" reliefs required in the enclosure that you are using.

Guessing done for now.   Good Luck,  Vic

[Halfcrazy]

Typically everything is using 1000 volt PV wire now, We have 1/2 strain reliefs that work for 1000v wire

http://www.midnitesolar.com/productPhoto.php?product_ID=520&productCatName=Accessories&productCat_ID=5&sortOrder=11&act=p