DIY Universal Battery Backup For Your Reef

[ApexConsumer]

Can't figure find a definitive answer to the grounding question online. I don't see it mentioned in this diy thread.

I always thought a ground was necessary. So i bought a 6 foot grounding rod and plan to cut it in half. One half for the inverter and the other half for a generator. i will drive it in the ground outside and run a wire through the wall to the inverter ground bolt.

Anyone have any thoughts on this?

 

[Turbo's Aquatics]

2x 3' rods may not be as effective as one 6' rod. It's about getting down to the water table, so the shallower you go, the less ground connection you are going to have.

This all depends on your geographical location and your soil conditions. But in many places, to get <5 ohms to ground, you need 2 or 3 8' rods that are at least 10 apart from each other.

Also you don't really need to (and you may actually not want to) put in separate ground rods that are isolated from each other - you can create floating grounds, and have small currents passing through non-grounded conductors and funny things like that. You can have dedicated ground rods, but you want to also tie all of those together and bring them all back to the ground on your main electrical panel, which is where all the grounds should go back to.

Also all your neutrals should go back to the main service panel, and that's where you generally would bond your ground & neutral together (there and only there)

 

[KStatefan]

If you want to learn more about bonding and grounding this is a good article

https://www.mikeholt.com/instructor2/img/product/pdf/1292432628sample.pdf

 

[siggy]

Anyone have any thoughts on this?

https://www.ecmweb.com/code-quiz-day/grounding-electrode-burial-depth-requirements
Article 250 covers the requirements for bonding and grounding. Part III of this Article focuses on the grounding electrode system and grounding electrode conductor requirements. As noted in 250.53(G), "The electrode shall be installed such that at least 8 ft of length is in contact with the soil. It shall be driven to a depth of not less than 8 ft except that, where rock bottom is encountered, the electrode shall be driven at an oblique angle not to exceed 45 degrees from the vertical or, where rock bottom is encountered at an angle up to 45 degrees, the electrode shall be permitted to be buried in a trench that is at least 30 in. deep."

 

[ApexConsumer]

Thanks for the info. I will buy 1 8ft ground rod for use with the inverter and generator. Do I also need to ground back to the house ground rod since this is a separate system much like a generator that is not wired into the house lines? If I do need to ground to the house, can i just attach to the house ground by attaching the inverter ground to a house outlet ground wire?

There are no inputs into the house system from the inverter, only 2 outputs from the house and both of those should use the house ground, right?

1. The transfer switch which I believe will use the house ground when the house power is on / inverter off. However, i don't think the inverter will use the house ground through the transfer switch when the inverter is on / house power off, but I will test it.
2. Battery tender connects to the battery terminals when charging (house power on / inverter off).

 

[ApexConsumer]

I have been researching...
I have a kreiger kr2000 msw inverter and xantrex 8080915 transfer switch. I think the answer is if the transfer switch transfers the ground. Grounding rod required if it does not.

Feature Article
Mar/Apr 2003
IMSA Journal
IMSA Home


Generator Grounding
When are Ground Rods Required at Portable Generators?

Portable generators are often used for backup power at traffic signals, buildings, structures and special events. Ground rods (grounding electrodes) are only required if the generator is a separately derived system. (For the complete text of sections cited please see the 2002 NEC)

What is a Separately Derived System?
The NEC in Article 100 defines a Separately Derived System as:
Separately Derived System. A premises wiring system whose power is derived from a battery, from a solar photovoltaic system, or from a generator, transformer, or converter windings, and that has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system. [See Fig 1]

The key to knowing if a generator is a Separately Derived System is not the generator, but rather the transfer switch. If the transfer switch does not transfer the neutral (grounded conductor), then the generator has a “solidly connected” grounded circuit conductor and the generator is not a separately derived system. [See Fig 2]

If the generator is connected to a transfer switch that transfers the neutral, and the generator does not have a “solidly connected” grounded circuit conductor, then it is a separately derived system. A separately derived system requires a connection to a grounding electrodes or ground rod(s).

A transfer switch is required between the generator and connected load. It provides isolation and prevents backfeed to the utility source from the generator. New for the 2002 NEC is Section 702.6 Transfer Equipment, which requires suitable equipment for the use, designed and installed so as to prevent the inadvertent interconnection of normal and alternate sources of supply in any operation of the transfer equipment. Interlocked circuit breakers or manual double pole, double throw, center off switch can be used.

Why Do Separately Derived Systems Require a Ground Rod?
Article 250 has the requirements for grounding of systems. In Section 250.20 Alternating-Current Circuits and Systems to Be Grounded, Part (D) states that systems covered in 250.20(A) or (B) are to be grounded per 250.30. A fine print note clarifies the connection of a generator:
FPN No. 1: An alternate ac power source such as an on-site generator is not a separately derived system if the neutral is solidly interconnected to a service-supplied system neutral.


Part (B) is for AC systems over 50 V:
· 120V or 120/240V single phase
· 277/480Y 4 wire, three phase, 120/208V 4 wire, three phase
· 120/240V 4 wire, 3 phase delta

These are the typical AC systems used for traffic signal or roadway lighting applications.

Section 250.30 Grounding Separately Derived Alternating-Current Systems, gives the requirements for grounding. A common type of Separately Derived Service is a 480 x 120/240V step down transformer. When there is no direct electrical connection to the primary grounded conductor, and the secondary grounded conductor must be connected to a grounding electrode system.

What is the Purpose of the Ground Rod?
The ground rods serve no purpose in clearing line to line or line to case faults. An electrical system will operate “ungrounded” and some industrial systems are designed to operate ungrounded. The purpose of the Ground Rod, or more accurately Grounding Electrode System is given in Section 250.4(A) (1) and (2):
(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.
(2) Grounding of Electrical Equipment. Non–current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.

Authors Note: A ground fault at a metal street lighting pole, with a ground rod but no low impedance (green wire) path back to the source, does not allow sufficient current to flow to open the over current protective device when using the earth as the sole return path. Even at 25 ohms ground resistance, a ground rod will not assist in clearing the fault for a 120 V supply source. At 25 ohms resistance the maximum current will be 4.8 amps at 120V. The metal lighting pole will remain energized and a serious shock hazard. A supplemental grounding electrode can be added at street lighting and traffic signal poles, but Section 250.54 states the earth shall not be used as the sole equipment grounding conductor.

Most generators are connected through transfer switches that do not transfer the neutral. Switching the neutral is done by design, due to other electrical requirements.
Where required for a generator, the purpose of the ground rod(s) at a generator is to limit the voltage from surges, lightning or unintentional contact with high voltage lines, and to limit the voltage to ground on conductive metal parts.

What About Portable and Vehicle-Mounted Generators?

Portable generators are covered in Section 250.34 Portable and Vehicle-Mounted Generators. This section allows the generator or vehicle frame to serve as the grounding electrode when:
(1) The generator supplies only equipment mounted on the generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and
(2) The non–current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.

Caution-Generator Neutral Grounding
Generators will often have the neutral conductor bonded to the generator frame. This is commonly done on small portable generators supplied with receptacles. [Illustration 3]
Larger generators with a cord supplied pin and sleeve connector typically do not have the neutral grounded to the frame. There is no industry standard for when the neutral is or is not grounded, however it seems to be dependant on the generator having receptacles mounted on the frame, as then the neutral is grounded to the generator frame. The generator user needs to know if the neutral is grounded or not.

If the generator neutral is grounded then the generator can only be used with a transfer switch that transfers the neutral, or as a stand alone generator for a carnival or special even, and then ground rods are required.

http://www.imsasafety.org/journal/ma03/ma5.htm
Feature Article
Mar/Apr 2003
IMSA Journal
IMSA Home


Generator Grounding
When are Ground Rods Required at Portable Generators?

Portable generators are often used for backup power at traffic signals, buildings, structures and special events. Ground rods (grounding electrodes) are only required if the generator is a separately derived system. (For the complete text of sections cited please see the 2002 NEC)

What is a Separately Derived System?
The NEC in Article 100 defines a Separately Derived System as:
Separately Derived System. A premises wiring system whose power is derived from a battery, from a solar photovoltaic system, or from a generator, transformer, or converter windings, and that has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system. [See Fig 1]

The key to knowing if a generator is a Separately Derived System is not the generator, but rather the transfer switch. If the transfer switch does not transfer the neutral (grounded conductor), then the generator has a “solidly connected” grounded circuit conductor and the generator is not a separately derived system. [See Fig 2]

If the generator is connected to a transfer switch that transfers the neutral, and the generator does not have a “solidly connected” grounded circuit conductor, then it is a separately derived system. A separately derived system requires a connection to a grounding electrodes or ground rod(s).

A transfer switch is required between the generator and connected load. It provides isolation and prevents backfeed to the utility source from the generator. New for the 2002 NEC is Section 702.6 Transfer Equipment, which requires suitable equipment for the use, designed and installed so as to prevent the inadvertent interconnection of normal and alternate sources of supply in any operation of the transfer equipment. Interlocked circuit breakers or manual double pole, double throw, center off switch can be used.

Why Do Separately Derived Systems Require a Ground Rod?
Article 250 has the requirements for grounding of systems. In Section 250.20 Alternating-Current Circuits and Systems to Be Grounded, Part (D) states that systems covered in 250.20(A) or (B) are to be grounded per 250.30. A fine print note clarifies the connection of a generator:
FPN No. 1: An alternate ac power source such as an on-site generator is not a separately derived system if the neutral is solidly interconnected to a service-supplied system neutral.


Part (B) is for AC systems over 50 V:
· 120V or 120/240V single phase
· 277/480Y 4 wire, three phase, 120/208V 4 wire, three phase
· 120/240V 4 wire, 3 phase delta

These are the typical AC systems used for traffic signal or roadway lighting applications.

Section 250.30 Grounding Separately Derived Alternating-Current Systems, gives the requirements for grounding. A common type of Separately Derived Service is a 480 x 120/240V step down transformer. When there is no direct electrical connection to the primary grounded conductor, and the secondary grounded conductor must be connected to a grounding electrode system.

What is the Purpose of the Ground Rod?
The ground rods serve no purpose in clearing line to line or line to case faults. An electrical system will operate “ungrounded” and some industrial systems are designed to operate ungrounded. The purpose of the Ground Rod, or more accurately Grounding Electrode System is given in Section 250.4(A) (1) and (2):
(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.
(2) Grounding of Electrical Equipment. Non–current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.

Authors Note: A ground fault at a metal street lighting pole, with a ground rod but no low impedance (green wire) path back to the source, does not allow sufficient current to flow to open the over current protective device when using the earth as the sole return path. Even at 25 ohms ground resistance, a ground rod will not assist in clearing the fault for a 120 V supply source. At 25 ohms resistance the maximum current will be 4.8 amps at 120V. The metal lighting pole will remain energized and a serious shock hazard. A supplemental grounding electrode can be added at street lighting and traffic signal poles, but Section 250.54 states the earth shall not be used as the sole equipment grounding conductor.

Most generators are connected through transfer switches that do not transfer the neutral. Switching the neutral is done by design, due to other electrical requirements.
Where required for a generator, the purpose of the ground rod(s) at a generator is to limit the voltage from surges, lightning or unintentional contact with high voltage lines, and to limit the voltage to ground on conductive metal parts.

What About Portable and Vehicle-Mounted Generators?

Portable generators are covered in Section 250.34 Portable and Vehicle-Mounted Generators. This section allows the generator or vehicle frame to serve as the grounding electrode when:
(1) The generator supplies only equipment mounted on the generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and
(2) The non–current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.

Caution-Generator Neutral Grounding
Generators will often have the neutral conductor bonded to the generator frame. This is commonly done on small portable generators supplied with receptacles. [Illustration 3]
Larger generators with a cord supplied pin and sleeve connector typically do not have the neutral grounded to the frame. There is no industry standard for when the neutral is or is not grounded, however it seems to be dependant on the generator having receptacles mounted on the frame, as then the neutral is grounded to the generator frame. The generator user needs to know if the neutral is grounded or not.

If the generator neutral is grounded then the generator can only be used with a transfer switch that transfers the neutral, or as a stand alone generator for a carnival or special even, and then ground rods are required.

 

[ApexConsumer]

So I could not find info on the transfer switch ground so just plugged everything in and tested it for ground with house power (grounded) and inverter power (not grounded). So I need a ground. The house ground rod is only 30 ft away so I will be running a 4 gauge solid copper wire to ground it directly.

 

[laverda]

I am setting up a test system and am a little confused about where to ground the inverter.

Do I ground it to the house ground somehow or do I need to have it hooked up to a separate grounding rod?

System:
Kreiger 2000w modified sine wave inverter (has a grounding bolt built in)

100ah 12v agm battery- ub121000

Transfer switch xantrex

Battery tender 3a version (plugged into the house power so will only charge the battery when there is power)

I plan to only power my jaebo return pump dcp-6500 for now. I know the modified sine wave inverter is not ideal for the pump.

Any help is appreciated.

I wired in some jacks directly to the battery so I can run 12 pumps directly. Your battery will run the pump longer that way since you not wasting power converting to AC and back to DC again.

 

[laverda]

So I could not find info on the transfer switch ground so just plugged everything in and tested it for ground with house power (grounded) and inverter power (not grounded). So I need a ground. The house ground rod is only 30 ft away so I will be running a 4 gauge solid copper wire to ground it directly.

I am pretty sure you need both the natural and ground hooked up to the house panel independently via the transfer switch. The switch should not disconnect the neutral or ground. I think you need to seek the advice of a certified electrician in your area that knows local codes.

 

[aqua_code]

Thanks for this whole write up. Really inspired me. I purchased the lead acid battery, a charger, and Aims Power PWRIX120012SUL 1200W Pure Sine with Transfer Switch. Will report back when it's up and running.

 

[TheSheff]

someone may have asked this, but what about using an inverter with a built in transfer switch? looking at this one : POTEK 2000W Pure Sine Wave Inverter with Automatic Transfer Switch 12V DC to 120V AC and Bluetooth https://a.co/d/6Zkp7YP

 

[soeminpaing]

Just use these ups module. It is easy to assemble. These are dc ups design for cctv. For vortech I use 4 x 32650 lifepo4 battery with 4s bms and plug directly into the 3.5 mm input port of vortech controller. I just need to charge the battery with 14.6v 2A charger.

 

[VintageReefer]

Portable Power Station 600W (642.6Wh/120V) Solar Generator (Solar Panel Not Included) with 60W USB-C PD AC Output Flashlight for Outdoor Camping Emergency Home Blackout Hunting RV Travel https://a.co/d/6T78axd

$250 for 642 watt hours of backup power

(642 *.85) / 25w = 21.8 hours of runtime for 250$

It’s battery + sine wave inverter + charger in one.

You can get smaller ones, the 300wh power stations would last 10 hours and are frequently 120-150$

I have 3 (one for each tank) and they power pumps through average non climate disaster (hurricane, tornado, etc) power outages

I use dc return pump on my main, it normally uses 40w and during outage I dial it down to 25w. This give me circulation AND filtration as my sump has cryptic zone with live rock and sand. I could also plug in my turf scrubber led and gain full filtration for minimal addition of watts.

Nano tanks return pump is like 10w and would last 25 hours on the cheaper 300wh station

 

[VintageReefer]

[10ms UPS/2Hrs Charge to 100%] BigBlue Portable Power Station Cellpowa 600, 537.5Wh Solar Generator, LFP Battery Backup with Pass-through Charging, 100W USB-C for Camping/RV/Power Outage/Off-grid Use https://a.co/d/4TmKoLO

$250 for 537wh and built in transfer switch, plus a 300w fast charger