Hi Brian,
The N.E.C. says one size under is good for your shore power. Understand the N.E.C. does not cover your boat
specifically, just electrical installation in general.
consider each system as its own system. this is why:
1. when connected to shore power only the shore power will go to ground.
2. the other systems (DC) are grounded for lightning not for a power grounding path.
Two schools of thought on grounding your system as a "Faraday cage" for lightning are considered by the pros.
one is don't!! unless all things metal on the boat are part of the ground system. Any metal not connected to your ground plate
will be a source of failure in the event of a lightning strike. This includes anything metal you bring aboard with you when prepare
for your passage. ie. your jewelry, coffee cup ...
This grounding has little to do with power and wire size on your boat and everything to do with lightning rods and such.
Two ground for lightning. but leave it to the pros so you don't forget anything. Note all wire paths should have smooth transition
when changing any direction and the main wire path from the grounding rod should go directly to your grounding plate.
Those that ground for lightning for a living are divided on how they have their own boats grounded. Many have their boats set up for a floating
electrical system to avoid the above problem with grounding the system. Others will ground. I assume they are strongly set on storing all
metal Items in the grounded oven should a storm greets them at sea.
On Sat, Jan 26, 2019 at 4:37 PM 'james@deny.org' james@deny.org [electricboats] <electricboats@yahoogroups.com> wrote:
From each separate system to the bus bar, is normally the largest size just for that individual system. You did not mention what you will be grounding to: dyna-plate, boat shaft, or other path to earth ground. That wire size should be the largest for all systems.In a boat with a mechanical engine, that is normally the 12/24 volt systems ground. Which is earthed via the engine block via the shaft.. Which is normally the largest gauge anyways do to being the lowest voltage, highest amperage circuits on a normal boat.On an electric boats that may not be the case. So first you need to understand what is the lowest resistance path to earth ground, that is also correctly sized to handle the combined grounding needs of all systems that are connect to the grounding system. This assumes none of those systems are floating systems, and have no earth ground by design and then should be heavily insulated, with all devices attached to that system electrically isolated. So if you chose to float your 48 volt traction pack, then for example make sure your battery charger connected to mains power has isolated outputs. (normally this only apply to fairly high-end and specialty chargers.)So the first thing you need to do is identify your path to earth ground. If you removed the old engine, you may no longer have one. And will need to create a new properly sized earth ground.
On Jan 26, 2019, at 6:00 AM, Chris Hudson clh5_98@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:Brian,
Even though not considered high voltage, some people keep their 48V system ungrounded. I think this is addressed in the high voltage standard TE-30, although I've never seen it.ChrisSent from myPhone
On Jan 25, 2019, at 21:27, DAN HENNIS dhennis@centurytel.net [electricboats] <electricboats@yahoogroups.com> wrote:I don"t do ABYC very well yet, but I believe the NEC wants your first choice. Think of it logically, if your supply is say 15 amps, then use the size for that supply. Each supply gets a wire to the buss. It does no additional good to put #2 for a ground when a 12 is the supply size. (IMHO)Dan----- Original Message -----
From: kd5crs@gmail.com [electricboats] <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Mon, 21 Jan 2019 11:45:35 -0500 (EST)
Subject: [Electric Boats] Ground wire sizingHello all, I have a sanity-check question to make sure I'm interpreting ABYC correctly for my electric boat conversion.I have 3 electrical systems onboard:1. Shore power, 120VAC 30A, dock only, no inverters. 10AWG from inlet to main panel. Branch circuits (all 15A breakers) are 12AWG.2. 48V electric motor, max amperage 120A. 2AWG from pack to motor.3. 12V accessory power... Actual max amperage is very low (just LED running lights and a radio), but I'm sizing the wires from the battery to the DC panel for the max panel amps, so I'm using 4AWG from battery to panel. Branch circuits are 16AWG.My plan is to use a bus bar (probably the Blue Sea MaxiBus 250A 4 post) as the common grounding point.I'm looking at ABYC E-9 (13) figure 15, DC NEGATIVE SYSTEM - DC GROUNDING SYSTEM. My takeaway here is that each system should using a grounding wire the same size as its biggest wire size. So the Shore power panel to ground should be 10AWG, the 48V battery to ground should be 2AWG, and the 12V battery to ground should be 4AWG. However, the alternate interpretation is that all wires should be the largest size, so all three need to be 2AWG.So which way is right: each system uses the size of its largest conductor (10, 2, and 4, Dr Pepper time), or every system uses the size of the largest conductor (2AWG).Thanks,Brian
--Dan HennisCTR ServicesP.O.. Box 25414237 FR 1155Cassville, MO 65625-0254417-396-0228
__._,_.___
Posted by: Kevin Pemberton <pembertonkevin@gmail.com>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a New Topic | • | Messages in this topic (6) |
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.
SPONSORED LINKS
.
__,_._,___
No comments:
Post a Comment