8:25 THWN-2 wires are usually up to 600V and PV wires are rated 1kV or 2kV. I've never seen THWN-2 wires rated for 1kV. Probably would not be a good idea to transition inside the junction box since most PV installations are 1000V or 1500V these days.
Thank you for your comment MWSC. You are right. The voltage rating of wire is very important when planning out a system and also buying wire. For residential systems, we are only able to create series strings of modules up to 600V (according to NEC 290.7). In this case, any THHN, THWN-2, etc wire would be adequate for the transition in a Jbox from the roof to ground through conduit, for example. In fact if you go to a big box hardware store like Home Depot you can buy wire that is marked several types: THHN, THWN-2, and MTW on the same piece of wire. However it is only 600V rated though. If you want wire rated for more voltage, PV wire is rate for 600V, 1000V, or 2000V (and this follows NEC section 490), as you have mentioned MWSC. You would typically have to buy this PV wire from an electrical supply house (like Platt) or a PV wholesaler - and it comes in colors which is helpful for keeping track of positive and negative in long strings. Most PV modules these days have PV wire coming out of their attached JBoxes using 1000V PV wire and the module assemblies themselves are rated for up to 1000V commercial installations. It is important to know the Voltage rating of all these components through the system so they all match as you have implied. Also, when you start to size systems larger than 600V you will typically be paying more for the wire, terminals, combiners, disconnects, etc. that can handle those higher voltages. Great comment. Thank you,Solar Professor
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Great breakdown of all the non-main components. Easy to understand. Thank you!
8:25 THWN-2 wires are usually up to 600V and PV wires are rated 1kV or 2kV. I've never seen THWN-2 wires rated for 1kV. Probably would not be a good idea to transition inside the junction box since most PV installations are 1000V or 1500V these days.
Thank you for your comment MWSC. You are right. The voltage rating of wire is very important when planning out a system and also buying wire. For residential systems, we are only able to create series strings of modules up to 600V (according to NEC 290.7). In this case, any THHN, THWN-2, etc wire would be adequate for the transition in a Jbox from the roof to ground through conduit, for example. In fact if you go to a big box hardware store like Home Depot you can buy wire that is marked several types: THHN, THWN-2, and MTW on the same piece of wire. However it is only 600V rated though. If you want wire rated for more voltage, PV wire is rate for 600V, 1000V, or 2000V (and this follows NEC section 490), as you have mentioned MWSC. You would typically have to buy this PV wire from an electrical supply house (like Platt) or a PV wholesaler - and it comes in colors which is helpful for keeping track of positive and negative in long strings. Most PV modules these days have PV wire coming out of their attached JBoxes using 1000V PV wire and the module assemblies themselves are rated for up to 1000V commercial installations. It is important to know the Voltage rating of all these components through the system so they all match as you have implied. Also, when you start to size systems larger than 600V you will typically be paying more for the wire, terminals, combiners, disconnects, etc. that can handle those higher voltages. Great comment. Thank you,Solar Professor
@@solarprofessor7695 Thank you, Sir, for your detail explanation. I really enjoy all your tutorials.