Bonding.

[Alamak]

Hello. I have a question about bonding. How should I bond my solar panels to my electrical system. I have 10 400 watt panel mounted to unistrut.
Thank you so much for your wisdom.

[desrtdog]

Originally Posted by Alamak

Hello. I have a question about bonding. How should I bond my solar panels to my electrical system. I have 10 400 watt panel mounted to unistrut.
Thank you so much for your wisdom.

What else is in your electrical system? Batteries, charger/inverter, shore power, etc? What voltage is your system? What loads are you trying to power - both AC and DC? A little more info will help people here to help you...

[Alamak]

Originally Posted by desrtdog

What else is in your electrical system? Batteries, charger/inverter, shore power, etc? What voltage is your system? What loads are you trying to power - both AC and DC? A little more info will help people here to help you...

It is still being built but I have 2 EG4 Batteries with a 3rd one in the future with a 6000XP INVERTER.
No split phase so only 120 with 12dc. Will have shore power. Generator.
Loads @ 120 are washer dryer, ( probably only on generator), refrigerator. Small microwave, mini split, yeah it's 120v. Lights.
12dc loads, water pump, maxair, tankless LP water heater uses DC for ignition, same with LP stove. Other moderate minor loads.
Sorry guy. I really appreciate the help with reminding me to include this info. New to this and the solar is a bit intimidating. I owned my own electrical contracting company for 21 years. Having said that, that experience is nothing like this and I knew that going in.
Thanks again.

[turf]

how are you mounting the panels?

imo, if you have metallic continuity between the solar panel, mounting rail, and roof support, you should be bonded to the frame.

do you have a standard bus or a fiberglass roof?

the electric supply house im getting my solar from has many do-dads that attach to aluminum solar frames and have a bonding screw if you need it.

since im fastened with metal fasteners from my metal roof, to metal rails, to metal solar panels, i'd consider that bonded but i should double check with a meter.

[AlphaHare]

Originally Posted by turf

how are you mounting the panels?

imo, if you have metallic continuity between the solar panel, mounting rail, and roof support, you should be bonded to the frame.

do you have a standard bus or a fiberglass roof?

the electric supply house im getting my solar from has many do-dads that attach to aluminum solar frames and have a bonding screw if you need it.

since im fastened with metal fasteners from my metal roof, to metal rails, to metal solar panels, i'd consider that bonded but i should double check with a meter.

100% this.

Bonding, meaning grounding the PV frames, should be possible just with the mounting hardware. If necessary, you could run a ground wire from the aluminum frame to the skin (if metal) or the frame hoops.

Do NOT tie the panel DC negative to anything other than a junction box and ultimately the DC negative primary bus bar.

This is an awesome resource from Victron (that applies to any system):

https://www.victronenergy.com/upload...ted-pdf-en.pdf

[DeMac]

Originally Posted by Alamak

It is still being built but I have 2 EG4 Batteries with a 3rd one in the future with a 6000XP INVERTER.
No split phase so only 120 with 12dc. Will have shore power. Generator.
Loads @ 120 are washer dryer, ( probably only on generator), refrigerator. Small microwave, mini split, yeah it's 120v. Lights.
12dc loads, water pump, maxair, tankless LP water heater uses DC for ignition, same with LP stove. Other moderate minor loads.
Sorry guy. I really appreciate the help with reminding me to include this info. New to this and the solar is a bit intimidating. I owned my own electrical contracting company for 21 years. Having said that, that experience is nothing like this and I knew that going in.
Thanks again.

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690.43 Equipment Grounding and Bonding.
Exposed noncurrent-carrying metal parts of PV module frames, electrical equipment, and conductor enclosures of PV systems shall be grounded in accordance with 250.134 or 250.136(A), regardless of voltage. Equipment grounding conductors and devices shall comply with 690.43(A) through (C).

(A) Photovoltaic Module Mounting Systems and Devices.
Devices and systems used for mounting PV modules that are also used for bonding module frames shall be listed, labeled, and identified for bonding PV modules. Devices that mount adjacent PV modules shall be permitted to bond adjacent PV modules.

(B) Equipment Secured to Grounded Metal Supports.
Devices listed, labeled, and identified for bonding and grounding the metal parts of PV systems shall be permitted to bond the equipment to grounded metal supports. Metallic support structures shall have identified bonding jumpers connected between separate metallic sections or shall be identified for equipment bonding and shall be connected to the equipment grounding conductor.

(C) With Circuit Conductors.
Equipment grounding conductors for the PV array and support structure (where installed) shall be contained within the same raceway, cable, or otherwise run with the PV array circuit conductors when those circuit conductors leave the vicinity of the PV array.


FYI:
250.136(A), Equipment Secured to Grounded Metal Supports.
The structural metal frame of a building shall not be used as the required equipment grounding conductor....





Ergo: bare copper & the proper lugs, torqued to spec, are required.

[turf]

Originally Posted by DeMac

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FYI:
250.136(A), Equipment Secured to Grounded Metal Supports.
The structural metal frame of a building shall not be used as the required equipment grounding conductor....





Ergo: bare copper & the proper lugs, torqued to spec, are required.

this is why my electrical threads get deleted

thank you DeMac for setting us straight.

so, whats it bonded to specifically? the battery negative? or the frame? or some other place?

here's my stupid question....if that or any of it gets hit by lighting, what happens?

[AlphaHare]

Originally Posted by DeMac

-----------

FYI:
250.136(A), Equipment Secured to Grounded Metal Supports.
The structural metal frame of a building shall not be used as the required equipment grounding conductor....

Ergo: bare copper & the proper lugs, torqued to spec, are required.

Not arguing, but wondering about interpretation of B in a mobile application.

Our school busses are metal, there is no earth bonding, the entire chassis is the de facto ground.

[Rucker]

Here's my beef: the title of this thread is Bonding, but we're not really discussing bonding in the context of a school bus conversion. Everything in the above thread that refers to bonding is more accurately described as grounding.

Demac can you take a look at the definitions section and see if that illuminates the discussion?

In the context of skoolies, bonding is the electrical connection between the neutral wire and the ground wire, and should only be done at the source of power: either at the main panel, the generator, or the inverter.

Without that clarification the above discussion is a bit out of context and perhaps confusing to some.

[AlphaHare]

I can see what you mean Rucker.

Article 100 definitions - this is it on 'bonding' - I think the last one is what you mean.

Bonded (Bonding). Connected to establish electrical continuity and conductivity.

Bonding Jumper. A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.

Bonding Jumper, Equipment. The connection between two or more portions of the equipment grounding conductor.

Bonding Jumper, Main. The connection between the grounded circuit conductor and the equipment grounding conductor at the service.

[Alamak]

That's what I was thinking. The roof is steel. Unistrut is steel. Bolts are galvanized. I am mounting panels to a plywood wall in the bay but I can bond easily to the frame right near the bus main bond.
I appreciate the info.

[DeMac]

Originally Posted by Rucker

Here's my beef: the title of this thread is Bonding, but we're not really discussing bonding in the context of a school bus conversion. Everything in the above thread that refers to bonding is more accurately described as grounding.

Demac can you take a look at the definitions section and see if that illuminates the discussion?

In the context of skoolies, bonding is the electrical connection between the neutral wire and the ground wire, and should only be done at the source of power: either at the main panel, the generator, or the inverter.

Without that clarification the above discussion is a bit out of context and perhaps confusing to some.

------------------


I didn't phrase the question. I read the first post, wondering if the OP knew the definition of bonding or the context of the question.

The second post notified us of the OP's previous electrical contracting experience. So I have a legitimate reason to believe she/he knows definitions used by the NEC, trade names & field definitions of the word 'Bonded'. To me, the question reads as the field definition "Bonded to the Grounding Electrode".


A shore power plug ought to be bonded to the ground via the Grounding Electrode.

If we are going to be using the chassis as the AC & DC systems' Earth Ground, we ought not be using the steel as the DC neutral.
Simple right? Run homerus for all of the DC neutrals and use the chassis as the ground. (gotta keep 'em separated)

When our rigs are plugged into AC shore power, our panel's ground bar, bus chassis and shore-power pedestal's Grounding Electrode become Bonded to the Earth.

[Rucker]

Originally Posted by DeMac

------------------


I didn't phrase the question. I read the first post, wondering if the OP knew the definition of bonding or the context of the question.

The second post notified us of the OP's previous electrical contracting experience. So I have a legitimate reason to believe she/he knows definitions used by the NEC, trade names & field definitions of the word 'Bonded'. To me, the question reads as the field definition "Bonded to the Grounding Electrode".


A shore power plug ought to be bonded to the ground via the Grounding Electrode.

If we are going to be using the chassis as the AC & DC systems' Earth Ground, we ought not be using the steel as the DC neutral.
Simple right? Run homerus for all of the DC neutrals and use the chassis as the ground. (gotta keep 'em separated)

When our rigs are plugged into AC shore power, our panel's ground bar, bus chassis and shore-power pedestal's Grounding Electrode become Bonded to the Earth.

Yes, well said.

I remember quite a bit of chatter that grounding your House AC ground to the bus chassis increases your risk of a hot skin condition. Technically true if a) you don't use grounded cords to power the house circuit from shore power and/or b) there is an open ground somewhere between shore power and the house circuit and c) the hot or load wire abrades and comes in contact with any part of the bus chassis and d) you are the shortest path back to ground because you are hugging your bus barefooted after a quick dip in the pond.

My position is that every house circuit is at high risk of abrading and shorting out against some piece of metal on a bus; therefore the more connectivity between all the pieces of metal on a bus whether an appliance, a handrail, the steel frame or chassis, the less likely the best return path for that heart-stopping current is through me.

And in case anyone's forgotten, the purpose of a ground wire is to provide a quick return path to the source of the power so that fuses and circuit breakers quickly pop and trip, preventing a conductor from becoming a filament....

The more connectivity the merrier.

And regarding DC neutrals, all you need to do is take an ohm meter and check the resistivity across any length of the bus chassis-usually there's very high Ohms (translation: high resistance to flow). Using a wire to complete the circuit back to the battery is the best way to ensure minimal voltage drop to your devices.

[nikitis]

When I was young and uneducated on electricity. I was wiring up a Harbor Freight fold up trailer, I couldn't get the lights to cut on and I couldn't figure out why. The wires were by default grounded to the frame. The positive wire had power and connectivity but the lights still wouldn't come on.

It turns out that the joint in the middle was painted and used a non-conductive bolt. So the circuit was in effect broken.

The wiring from the truck had a ground wire screwed into the frame up front by the hitch itself on the trailer body.

This may seem like nonsense to many but this made me realize that the frame itself was completing the circuit. And a ground is often larger than the positive power. I've worked with electronics long before I worked with household wiring or trailer/car/auto wiring. Electronic wiring should be more difficult to understand, but I learned that first. Electricity is really sound at it's most basic level. It helps when the ground plane is larger than the power plane as the ground creates a huge resistance. That resistance acts like a wall for the sound/electricity to kind of bounce off of and reaches your device more easily.

Compare it to a lake at the end of a river. And before the lake you have a water wheel. The water is the electricity flowing easily on the path of least resistance (Positive wire) which brings the electricity to the water wheel (Lights or devices) to turn it on. Or brings electricity to the device like a light to illuminate. Post water wheel the water spreads out into a lake which is wider but still connected to the river through water under the earth and re-circulating eventually out of the spring it originally came from.

With my Harbor Freight trailer, I decided to bypass the frame and run a ground wire directly to the ground wire up front so it wasn't using the frame for ground. This created less resistance, and the rear lights worked perfectly fine, and were in fact brighter due to there being less resistance in the ground. This one example taught me about grounding that I've been able to apply to all of my electrical projects, and was how I learned about it.

A bus frame is a large resisted plane, so you can use a lot of positive wire applications and they still won't meet or exceed the resistance of the body. You can even tie a solar system plus a bus system to the same ground plane as long as the positive planes don't cross each other.

And if there's ever a question on ground being an issue you can test by running a ground wire from end to end, and if it works suddenly your original ground plane either isn't connected or separated by something non-conductive.

As for lightning striking the bus. Your bus is insulated by rubber tires so it makes the body less likely to be struck by lightning. This applies to all cars as well. If you stick a grounding rod into the earth though, all bets are off and your bus becomes a lightning rod.