RV grounding

Re: RV grounding

zoneblue wrote: »

We are most worried about PV side shorts to chasis in an rv application. With a dc neg to chasis bond, this event would quickly blow a breaker to immediately notify the failure

What breaker would blow? PV panels should not be able to produce enough current to trip their own breakers.

--vtMaps

Re: RV grounding

That inverter is a real nice bit of kit. I just looked and victron appear to have an active marketing presence here in NZ as well.
See http://victronenergy.co.nz/index.php?route=product/product&path=68_60_76&product_id=96 Probably the main handbrake to more widespread adoption is the price, with Outback landing here a bit cheaper.

down under plumber wrote: »

thanks 4 the replies
i used 30 amps breakers as mainly disconnects yes the panels are in 2 strings
was my maths wrong i was expecting max 56 Amps out of the panels
ok should i have a fuse between the panels & controller ?

Sounds to me like you need to slow up a bit. The questions your asking indicate you have a bit more homework to do before your install will be a robust and safe one. First thing id do is order a midnite MNDC disconnect. It has all the right breakers you need already installed. They might also make a epanel for victron, i am not sure,dont think so. The beuty of using a disconnect is it safely houses all the dangerous unfused bits, out of harms way.

i no the inverter is large but the batteries r coping so far but it not finished yet i can ad a gen later if needed the inverter has a 120 amp (charger)

Well its not like you are using GC2s. But... peak draw from the inverter will be: 5000W / 23V * 1/0.88 = 250A. Double that under surge. Generally we say that flooded lead acid banks are good for 0.25C for longer duration discharges (which in your case is 100A), but it does depend on the battery concerned. For short duration they can handle 3C or so, but the efficiency falls right off, which means the banks capacity will become real small at those kind of rates. Fact is, youre mobile with limited charging sources, so you are obviously going to have use this (and any) inverter judiciously.

In case that isnt clear look at it this way: at 250A, the real capacity of your bank will be more like 200Ah. Start with a full batterry, run the inverter at 5kW and it will reach 50% DOD in 24 minutes, and by 40 odd minutes it will be completely flat.

The other factor is tare loss. That inverter clocks in at 25W which for an inverter of its size is really very good. 6W in search. However just note that 25W @ 24/7 amounts to 600Wh, which is around one quarter of your total production, and enough to power a decent fridge. In comparison the victron 3000W and 1600W models uses 10W/15W. Superb.

sorry what does float mean ?

[strike]Float is when the charge controller has completed the bulk and absorb stages and considers the bank charged. It charges at a lower voltage to maintain the bank, and support your loads.[/strike]
Edit: Float means neither neg nor pos are gounded. Low voltage systems, 12V and the like often run this way. In some situations there are advantages to doing this.

the solar goes to the main - negative truck (chassis)
the batteries and breaker panel -(negative) go to the main - negative truck (chassis)
so where do i put the earth (ground) from the chassis of the inverter & controller

You should run a single earth point. The MNDC has a earth bus for this purpose. However in the first instance the pv neg, the inverter neg, and the controller neg should all run to the neg bus. Then if you decide to earth bond the dc side, or use a GFI device, then you do that between the neg and ground buses.

Yeah, these installs are kind of involved... Do you have a mate that can help you out with this install at all? Looks like someones crimped you up some nice looking cables and what not.

1 do i run it to a RCD
2 do i run it to the truck chassis
in the photo its the terminal bottom left of the photo

The AC side is another matter altogther. I suggest you concentrate on the DC side first, and get that right. Batterys are suprisingly dangerous, and a good clean install is your goal there. Lots of conduit, tidy cable management, and all the required proper industry std DC rated breakers in all the right places. (Blueseas gear is OK, but doesnt really belong in a sytsem like yours. Check out midnites line of breakers. They are pretty cheap, and have huge interupt capacity, which is what allows off gridders to sleep at night.

Then we can come back and deal with the AC side. Youll also will want to get a sparky to oversee the AC side, if you want to get your RV electrical warrant of fitness. For a couple hours "sign off" its cheap peace of mind.

Re: RV grounding

Very similar reasoning occurs on the ac side. As you have seen the scenarios that negative and neutral to earth bonding are designed to protect against from are quite obscure. On the AC side, to get a belt off an unearthed AC line something like the following would have to occur.

1. Appliance A shorts hot to (metal) case. Goes undetected.
2. Appliance B shorts neutral to (metal) case. Goes undetected.
3. User reaches across (possibly large distance), and grabs a hold of both appliances.

Metal cases appliances are less and less as time goes on, being replaced with double insulation. Nonetheless netrual-earth bonding is the law of the land and wiser men than i made it that way, probably for on balance good reasons. Just because an RV isnt actual earth grounded, doesnt change all of the logic involved, but you will need to check what the regulations are in your country.

Heres a diagram i made on the midnite forum:
http://midniteforum.com/index.php?topic=1775.msg17446#msg17446

RCDs are new devices and are effectively another layer of protection, against appliance and wiring faults.

On an RV you have additional vibration/movement concerns, and having immediate notifiction , via either a fuse pop, or rcd trip, of any short is really useful and possibly lifesaving.

Of course alot of people get away with plugging things straight into outlets that are on the (mobile) inverter itself, and this is only safe with a single appliance. Once you get into double adapters you are back into the worry area as above. Some inverters have RCDs inside and may or may not help there.

However Rv grounding has other issues. Like the changes that occur when connected to shore power. You are then (possibly) real earth grounded as well. While you are inside and untethered to shore power your chasis is your earth. Things can go pear shaped when you step off the rv onto the ground holding the rail. Things can also go horribly pear shaped when tethered to a faulty shore power connection. Im no expert there, but there is a comprehensive FAQ on this forum on the matter.

So when in doubt seek expert advice.

Re: RV grounding

In the south pacific, phase/hot was changed from red to brown some years back. Neutral went from black to blue. This was because color blind sparkys cant distinguish red and green. Earth is now green with a yellow stripe.

Prior to 2003 RCDs were only fitted ,optionally, to bathrooms and the like. They are now required for the whole house, and 63amp models are readily available for that.

That board uses several rcd circuits with their own neg buses. The red double pole item in that board is the main switch.

NZ/AU plastic stuff must look as odd to you as your metal square d split phase stuff does to us.

CDN_VT wrote: »

Zone Blue
Your RCD's (residual current device)
are what we in North America call a GFI (Ground Fault Interrupter ) Breaker or receptacle type with built in tester.

Looking at the picture in midnight forum , Seeing Red as hot , black as also hot in my English home , and green for ground.

So now your asking the black hot to be a neutral and is the same potential as Ground ?

Here in NA split phase center neutral is bonded to ground in "Most" Fuse / circuit Breaker boards .

So your one red "HOT" wire is 230VAC to ground / return black wire now since 2003 ? And the 3 double wide are the RCD's with the orange test half moon push test? Whats the other double breaker ?

VT

Re: RV grounding

Thank You Zoneblue for the explanation . Now looking at the picture in depth & after your post I see the flow and the RCD buss.

I have never seen a Board so neat in any Square D or FPE style as your posted pix.

Thanks again .
VT