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Old 23-03-2021, 03:38   #1
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Appreciate help installing inverter

Installing 700 w inverter

Have some questions

1. How important is it to ground the inverter ?

Ground to engine block or water via seacock ?

2. When installing i plan to attach positive then negative. Is this ok ?

3. There is a 250 amp fuse in the positive battery terminal. This is a common fuse for all connections. Is this too high ?

Thanks in advannce
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Old 23-03-2021, 04:35   #2
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Re: Appreciate help installing inverter

1. Block is fine

2. That’s OK

3. At full load your inverter will pull roughly 60 amps @ 12vdc.
Your wire will be sized to supply this with minimal voltage drop. Your fuse will be sized to protect the wire that feeds the inverter.

In other words you question #3 doesn’t give enough information to answer.
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Old 23-03-2021, 04:47   #3
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Re: Appreciate help installing inverter

Thanks for your reply.

Is it ok if i dont connect ground to the inverter ?

I have a small 1.2 cubic ft isotherm fridge, furuno 1621 radar, lights, starting circuit on that 250 amp fuse. So my worry is that the fuse will not protect the wire to the inverter and maybe install its own 100 amp fuse ?
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Old 23-03-2021, 05:13   #4
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Re: Appreciate help installing inverter

Quote:
Originally Posted by arch007 View Post
Thanks for your reply.

Is it ok if i dont connect ground to the inverter ?

I have a small 1.2 cubic ft isotherm fridge, furuno 1621 radar, lights, starting circuit on that 250 amp fuse. So my worry is that the fuse will not protect the wire to the inverter and maybe install its own 100 amp fuse ?


Is the ac ground prong electrically connected to the battery negative? If yes, the grounding will be already taken care of, if not, you’ll have ungrounded AC appliances by not grounding the case.....your choice on planet safety.

That 250amp fuse is protecting the wire that feeds the branch circuits. Not the items attached.

What is the wire size for the inverter?
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Old 23-03-2021, 07:54   #5
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Re: Appreciate help installing inverter

Thanks for your help.

Wire size is 6 awg.

So since fuse is protecting wire the wire will burn before the fuse blows ?

Not sure all the wires connecting to the fuse are individually fused.

Sure the starter wire and wire to main dc panel are not.

Fridge, charger, bilge are fused.
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Old 23-03-2021, 08:18   #6
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Re: Appreciate help installing inverter

What is the make and model of inverter? Is the inverter designed to be hardwired into your system? Is it an inverter only or inverter/charger? Do you have shore power? Do you plan to use the inverter when you are not on shore power? If so, what is the transfer mechanism?

Comments:
It is important to ground the inverter. The case should be connected to both the AC and DC grounds. A DC negative bus bar is a better method of grounding than using the block. It allows for multiple connections and provides a common connection for all grounds. Attaching grounds to multiple points on the block is not recommended, as you are now inducing current through the block between those points. Sure you can do it, and people will chime and tell you so, but it's not recommended.

The output should be fused to protect the output wiring. What is the size of the wire?

The input should be fused at the battery bank end of the circuit, also to protect the wire. To size the fuse, you need the output in amps (58.33 or 60a nominal), the wire size (6 AWG) and the length of the wire run in both directions. There's a handy calculator at Circuit Wizard - Blue Sea Systems. Assuming a 10' roundtrip, your wire size is within limits and the recommended fusing is 60A.
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Old 23-03-2021, 08:42   #7
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Re: Appreciate help installing inverter

About 5-6 years ago when installing cheap 2kw/3kw peak inverter from HF I got the following advice from my marine pro buddy.
1. locate it as close to the battery connection as possible
2. ground to the most substantial ground i.e. the block
3. use the thickest wire you can afford. I went with either 1/0 or 2/0, I forget now. But he explained that not only this will prevent any issues with overheating but will allow for installation of a larger inverter without the need for rewiring.

As I got this model a few years before installation am thinking of updating to a more current model with more options such as 12v/USB jacks, etc.
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Old 23-03-2021, 10:24   #8
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Re: Appreciate help installing inverter

If the buss bar is a good place to attach the ground then would just connecting the ground terminal to the negative terminal be good enough? They both go to the same place.
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Old 23-03-2021, 10:36   #9
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Re: Appreciate help installing inverter

Quote:
Originally Posted by arch007 View Post
...............
.................................................. ....


3. There is a 250 amp fuse in the positive battery terminal. This is a common fuse for all connections. Is this too high ?

Thanks in advannce



It would help if you learned how and why fuses are sized and installed. Here's a good guide:


www.bluesea.com also has good material on this and fusing, but it's a PDF download and doesn't link. Here's the link to the page, scroll down for the PDF download of the Fuse & Wire Sizing Tables: https://www.bluesea.com/support/reference
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Old 23-03-2021, 10:40   #10
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Re: Appreciate help installing inverter

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Originally Posted by bcboomer View Post
If the buss bar is a good place to attach the ground then would just connecting the ground terminal to the negative terminal be good enough? They both go to the same place.
I'm not sure I understand the question. Do you mean the negative terminal on the battery? If so, the answer is yes. You can stack up to 4 connectors on a terminal post.

A bus bar typically has more than one post, and a boat typically has more than 4 circuits that need terminating. This makes a bus bar a better place to collect all the grounds than either a battery post or a bolt on the engine.
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Old 23-03-2021, 10:50   #11
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Re: Appreciate help installing inverter

No, I mean just a jumper between the ground and negative terminals on the inverter.
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Old 23-03-2021, 11:24   #12
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Re: Appreciate help installing inverter

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No, I mean just a jumper between the ground and negative terminals on the inverter.
The case ground serves a different function. If an internal fault sends current to the case, and the case itself is not grounded, then it can energize the case with possibly fatal results. The reason you ground the case to the both the DC negative bus AND AC ground is so that 1) a lower resistance path is created from the case to ground than going through the inverter negative and 2) this important protection cannot be interrupted by a fault in the wiring.
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Old 23-03-2021, 11:45   #13
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Re: Appreciate help installing inverter

The inverter is the renogy 700 watt inverter.

Straight inverter. Seperate promarine charger.

Inverter meant to be hard wired.

Plan to use it when off shore power.

Ac power is seperate from dc power.

Have a dynaplate to seawater which i am thinking of grounding inverter case to.

But thinking maybe dont need grounding case.

Install will connect positive then negative.

Inverter has remote off switch which will keep off to avoid parasitic leak.

Transfer switch not needed as inverter only.
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Old 23-03-2021, 11:53   #14
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Re: Appreciate help installing inverter

Thanks, I understand what you're saying but I can't see a significant difference in resistance. In 1 case you have say 5 feet of awg 6 cable from the case ground to the buss bar and in the other case you have a 3 inch jumper to the negative terminal and then 5 feet of awg 6 cable to the buss bar. I would think the chance of an internal fault at the same time as a failure in the negative cable is insignificantly small.
Is there some other factor at play?
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Old 23-03-2021, 19:04   #15
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Re: Appreciate help installing inverter

Quote:
Originally Posted by bcboomer View Post
Thanks, I understand what you're saying but I can't see a significant difference in resistance. In 1 case you have say 5 feet of awg 6 cable from the case ground to the buss bar and in the other case you have a 3 inch jumper to the negative terminal and then 5 feet of awg 6 cable to the buss bar. I would think the chance of an internal fault at the same time as a failure in the negative cable is insignificantly small.
Is there some other factor at play?
The result of that failure is entirely avoidable, and while the odds are small, could also be catastrophic. So what's the downside? 5 feet of cable and a few connectors? Cheap.

Proper grounding of the case has nothing to do with connecting your AC neutral and ground. What happens to your cross-connected ground and neutral while on shore power? They should be connected only at the source of power. If you're on shore power, the marina does that and neutral and ground should not be connected at the inverter. This might be irrelevant, as you haven't said what the rest of your system looks like or if you even have a shore power AC system.
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