Wire size from combiner box to E-panel

[hammick]

I figured everything out and ordered my system. Thanks for all the advice. You guys have been very helpful.

I don't just rely on advice here since a lot of times it is conflicting. I have checked everything with code, Midnight Solar tech, Schneider tech and lots of research so I am good to go.

I learned years ago not to rely on just one person even if they are licensed in their trade. I had an electrician install a subpanel when I finished my basement. Subpanel was right next to the main panel. He bonded the neutral bus to ground in the subpanel even though the main panel was bonded. He sort of knew what he was doing since he kept the neutrals and grounds separate. He didn't run a ground wire from the main panel. It cost me about $5 in wire to fix his mistake.

[hammick]

If I determine that metal clad cable satisfies the requirements of 690.31(E) do I need to bond the metal cladding to the EGC or does using metal snap fittings effectively bond the metal clad sheath from combiner box to E-panel? The 6/2 mc cable I am considering has an insulated EGC inside as well.

[inetdog]

If I determine that metal clad cable satisfies the requirements of 690.31(E) do I need to bond the metal cladding to the EGC or does using metal snap fittings effectively bond the metal clad sheath from combiner box to E-panel? The 6/2 mc cable I am considering has an insulated EGC inside as well.

Current construction MC has a bare bond wire inside the metal jacket whose purpose is to insure a good conductive bond across the spirals of the metal shell. It does not have to be terminated in any way and normal metal fittings clamping down on the shell are sufficient for EGC. The insulated ground sounds like you have hospital grade, used when two independent ground paths are required.
The earliest MC did not have the bond wire, nor the insulated ground and would get very hot under fault current. There is nothing you can do to make that compliant for new installations.

Very similar in appearance is AC (Armored Cable) and its metal sheath is approved for grounding with no need for a bond wire. Again, listed fittings for that cable type will provide EGC continuity.

[hammick]

Thanks Inetdog. This is the wire I am thinking about ordering: https://www.platt.com/platt-electric...px?zpid=481444

[Sunking]

Hammick take this advice. Never ever no matter what take the manufactures advice when it comes to code. The only correct advice is what the AHJ wants. Sometimes when even the AHJ will not accept even what the NEC. A really good example is 2014 ground PV arrays. Most jurisdiction will not accept it.

There are two rules you must follow and remember when dealing with Inspectors and Wives.

1. Your Wife or Inspector is always right without question.
2. If your Wife or Inspector is wrong, refer to Rule 1 for guidance and resolution.

[hammick]

Hammick take this advice. Never ever no matter what take the manufactures advice when it comes to code. The only correct advice is what the AHJ wants. Sometimes when even the AHJ will not accept even what the NEC. A really good example is 2014 ground PV arrays. Most jurisdiction will not accept it.

There are two rules you must follow and remember when dealing with Inspectors and Wives.

1. Your Wife or Inspector is always right without question.
2. If your Wife or Inspector is wrong, refer to Rule 1 for guidance and resolution.

Sunking while I agree with you I am in a situation where there really is no AHJ. I'm in an area where no permits are required. I had no building permits. I am lucky that I found a good honest contractor who went above and beyond any building code requirements.

So that is why I am researching, talking to Midnight Solar and asking questions on these forums. It would be nice if I have an inspector that would tell me what needs to be done. Isn't going to happen so I am figuring it out on my own.

I feel I will have a very safe system when done. There are things I think are not particularly needed in my install but I'll follow the rule anyway. For example the 12 - 15' run from my combiner box to my E-panel needing conduit. My combiner box is inside and the wire will run in an open 2x6 stud cavity. I feel the conduit requirement is kind of silly for my situation. But I will use the MC cable to meet code.

The 250a DC fuse is what the manufacture wants and is code compliant with the 4/0 cable. However I plan to put fuses on both + and - battery terminals appropriate for my max load current.

When the property is not occupied I will shut down everything except the charge controller. Each string has its own breaker and I will have breakers before and after the CC. Both terminals of the battery will have breakers. How can I make it any safer?

Once thing I haven't decided on yet is whether I will follow the NEC and rely on the ground fault of my CC and not ground the negative battery terminal. I'm inclined to follow the NEC but I know a lot of qualified people think this is the less safe route.

[Living Large]

There are two rules you must follow and remember when dealing with Inspectors and Wives.

1. Your Wife or Inspector is always right without question.
2. If your Wife or Inspector is wrong, refer to Rule 1 for guidance and resolution.

This is why I never got married. I don't need no inspector ordering me around and telling me I am wrong when I am right. If I'm wrong, I have the privilege of telling myself I'm right, and to not be questioned. It's a bit lonely at times, but I never get into an argument.

[Sunking]

I don't need no inspector ordering me around and telling me I am wrong when I am right.

Well I believe you have never married. If you had ever been married, they you would know you are ever right.

[Sunking]

Sunking while I agree with you I am in a situation where there really is no AHJ. I'm in an area where no permits are required. I had no building permits. I am lucky that I found a good honest contractor who went above and beyond any building code requirements.

So that is why I am researching, talking to Midnight Solar and asking questions on these forums. It would be nice if I have an inspector that would tell me what needs to be done. Isn't going to happen so I am figuring it out on my own.

OK that can bee a very good thing on the wallet without sacrificing safety and function.

The 250a DC fuse is what the manufacture wants and is code compliant with the 4/0 cable. However I plan to put fuses on both + and - battery terminals appropriate for my max load current.

RED FLAG CAUTION: I know you think this is going above and beyond minimum requirements, but the reality could be deadly at worse, dangerous at least. If your system is Grounded not only what you propose does not comply with code, is also extremely dangerous. In a grounded system where one of the load conductors is Grounded, you cannot install any switches breakers, fuses, or anything that may open the circuit. All the grounded circuit conductors must use bonding means that cannot be disconnected. Two real bad things happen:

1. It defeats short circuit protection, and prevents your fuses of breakers from operating.
2. It turns you safe to touch grounded circuit conductors into Hot Live Conductor that can electrocute you. So if you ever needed to work or test the system leads to false belief the grounded circuit conductors and can be handled when in fact they are hot waiting to nail your arse.

Once thing I haven't decided on yet is whether I will follow the NEC and rely on the ground fault of my CC and not ground the negative battery terminal. I'm inclined to follow the NEC but I know a lot of qualified people think this is the less safe route.

OK you only got things half right. It is a complicated and difficult to teach, even electricians have trouble grasping it. I am not going to try to teach you what is going on. It is literally a 1 semester course way outside the scope of the forum.

What I will tell you because it is all you really know is this:

1. A grounded system is a very simple passive protection system to allow the over current protection devices to operate properly.

2. Grounded systems are much less expensive to implement.

3. Although this is a gray area because some parts of your are less than 50 volts nominal on a 48 volt battery system, other parts of the system are greater than 50 volts. Code dictates non-grounded system be installed making all parts of the system must be made inaccessible, and only trained personnel shall be allowed to maintain the system.

[hammick]

RED FLAG CAUTION: I know you think this is going above and beyond minimum requirements, but the reality could be deadly at worse, dangerous at least. If your system is Grounded not only what you propose does not comply with code, is also extremely dangerous. In a grounded system where one of the load conductors is Grounded, you cannot install any switches breakers, fuses, or anything that may open the circuit. All the grounded circuit conductors must use bonding means that cannot be disconnected. Two real bad things happen:

1. It defeats short circuit protection, and prevents your fuses of breakers from operating.
2. It turns you safe to touch grounded circuit conductors into Hot Live Conductor that can electrocute you. So if you ever needed to work or test the system leads to false belief the grounded circuit conductors and can be handled when in fact they are hot waiting to nail your arse.

Thanks Sunking. I am well aware that there are well respected solar experts who disagree with the DC GFP requirement of the NEC. My Schneider has DC GFP built in so it is my belief that the negative terminal of my battery bank will be grounded (albeit through the DC GFP of my CC).

I am installing everything myself (except the panels and combiner box). I am pretty anal and will follow the torque requirements of all bus bars and breakers, will make sure no wires are compromised and that the battery cables are separated and cannot come into contact with each other even if a big pack rat goes to town on them. All EGCs will be properly terminated and run to my UFER ground.

So I believe my system will be NEC code compliant and would pass an inspection after the fact if ever required by my Insurer.

It sounds like you are saying putting DC fuses at the battery terminals in my situation is not a good idea? Anything else I can do to make my system safer?

My main concern is fire when I am away. I will be then only one operating or messing with my system and I always check conductors with a meter before I work on them. My second concern is that my CC breakers don't trip when I am away and my batteries self discharge and sulfate.

I know Midnight Solar has implemented ARC fault in their CC but my Schneider CC doesn't have that. I don't see that Midnight is offering external ARC fault DC breakers.

[Sunking]

My Schneider has DC GFP built in so it is my belief that the negative terminal of my battery bank will be grounded

Stick a fork in it, your done and is all you need to know. You cannot install fuses/breakers on both polarities. Only the non-grounded circuit conductors can have the OCPD installed. All the grounded circuit conductors, aka neutral, must be bonded solidly together with no switches, OCPD, or any device that may open the circuit. You have no choice.

The main benefit of using a non-Grounded System is to eliminate unnecessary outages that grounded systems are prone to. To exercise that option requires a lot of hoops to jump through, more complexity, more cost because it requires a lot more material and equipment to implement, and you still have to ground the equipment.

Now if you run a 12 or 24 volt system, panel Vmp voltage 50 volts or less, and not part of a premises wiring (your home) no problem running grounded or ungrounded system. The voltage is not considered high enough to electrocute you, and if not in a home or structure to catch fire and endanger the public, no one cares if you burn everything up. All the risk is on you in that case. Something goes wrong, you pay for it.

A picture is worth a thousand words. Partner no one here will ever do this for you. Yep I beat the crap out of you. Admit it, you like it.



Now it is time to tell you what you and most others do not know. Every Charge Controller out there has an internal bond from Chassis Ground to the Negative terminals. It does not meet code or designed to bond the system. That means you have absolutely no choice but to run a Grounded system. Catch is you CANNOT USE that Internal Bond to make the Ground Connection. You have to run the Bonding Jumper shown above. Gotcha.

Like I said never ever trust the equipment manufactures. That bonding jumper the secretly install covers their ass, not yours. It forces you to use a Grounded System. If you fail to do so, is your problem and responsibility if something goes wrong.

NOTE:

Take noticee there is two OCPD on the battery terminal. One facing the controller to protect the wiring between the Battery and Controller, and the other for the wire between Battery and Load device. Install them directly on the Battery Term Post, not downstream. For added protection install a protective barrier above the battery to prevent anything from falling on the term post that may short out the battery term post like a wrench. If that happens you have a big explosion and battery acid everywhere including you eyes. Best you could hope for is the explosion kills you instantly. Plexiglass works good for this using isolators. Another way is buy a non-conductive battery box as it ggive you two forms of protection.

1. Give you the protective barrier
2. Spill containment.

[inetdog]

Hammick take this advice. Never ever no matter what take the manufactures advice when it comes to code. The only correct advice is what the AHJ wants. Sometimes when even the AHJ will not accept even what the NEC. A really good example is 2014 ground PV arrays. Most jurisdiction will not accept it.

There are two rules you must follow and remember when dealing with Inspectors and Wives.

1. Your Wife or Inspector is always right without question.
2. If your Wife or Inspector is wrong, refer to Rule 1 for guidance and resolution.

Age old Zen question:
"If a man says something in the wilderness with no woman around to hear him, is he still wrong?"

[SunEagle]

Age old Zen question:
"If a man says something in the wilderness with no woman around to hear him, is he still wrong?"

You forget that even if the man is alone, Mother Earth is still present and she is female.

[J.P.M.]

You forget that even if the man is alone, Mother Earth is still present and she is female.

And those of us who were around 30+ or so years ago may remember the TV commercial with the admonition : "It's not nice to fool other Nature !! ".

[hammick]

Now it is time to tell you what you and most others do not know. Every Charge Controller out there has an internal bond from Chassis Ground to the Negative terminals.

See my first paragraph in post no. 25 above.