Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 23-06-2021, 18:18   #1
Registered User

Join Date: Sep 2020
Location: Im swimming in the Atlantic Ocean right now.
Boat: Approx 25 ft of blubber and muscle with big fins / natural selection- current state of evolution
Posts: 166
Is AC feeder bus ok to use?

I dont know if thats an official terminology. Is it ok to run the AC hot from my elci breaker to a small 4 post busbar and feed my AC sub panels from that bus instead of stacking wires on the elci breaker hot or running the hot from panel to panel?

I guess it would be similar to an DC always on charge bus which is how my DC side currently is set up. I'm just mulling over a future panel upgrade. I already have a small AC sub panel and an ELCI breaker, im thinking as i finalize the upgrade in the future i may need another small AC panel for a few more items.
BAD ORCA is offline   Reply With Quote
Old 23-06-2021, 18:21   #2
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft Catalina 381
Posts: 2,228
Re: Is AC feeder bus ok to use?

I'd be inclined to put in a small panel instead with breakers feeding each sub panel. If nothing else, it allows turning off just 1 sub panel for service.
rslifkin is online now   Reply With Quote
Old 23-06-2021, 18:44   #3
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 813
Re: Is AC feeder bus ok to use?

If I understand correctly your question, I think providing a small terminal strip to distribute power to several sub panels would be preferred to stacking a bunch of feeders/ lugs on a breaker stud. Just be sure the TS/ wiring is rated for the main breaker (probably 30 A) and secure and separate the hot leads from the grounds and neutrals if practical.

As I have repeated numerous times, a conductor can be protected from overcurrent any where along its length (beginning or end), protection against short circuits and ground faults at the source. Physical separation also works in the short circuit and ground fault condition.


Frankly
Frankly is offline   Reply With Quote
Old 23-06-2021, 22:14   #4
Registered User

Join Date: Sep 2017
Location: Langley, WA
Boat: Nordic 44
Posts: 1,731
Re: Is AC feeder bus ok to use?

Four AC subpanels? How large is the boat and how complex is the AC wiring?

Having asked that question the answer to your question is sure you can. It would be best (required) that the buss bar is covered to prevent electrocution.
stormalong is offline   Reply With Quote
Old 24-06-2021, 03:48   #5
Registered User

Join Date: Jun 2016
Location: Jensen Beach, Fl
Boat: O'Day 34
Posts: 328
Re: Is AC feeder bus ok to use?

Quote"As I have repeated numerous times, a conductor can be protected from overcurrent any where along its length (beginning or end), protection against short circuits and ground faults at the source. Physical separation also works in the short circuit and ground fault condition." End Quote

I have never posted a disagreement with a post on this forum but in this case I feel I must as someone following the above advice (repeated numerous times) could lead to a very hazardous situation.

A conductor's protection, fuse, or breaker should be located as near as possible to the power source, not anywhere along its length. Any part of the conductor located between the protection and the power source is unprotected in the event of a short circuit caused by chafing, etc. I saw this yesterday in a boat that I was working on. The ratty 10 gauge wire that powered the power panel on this open fisherman was ~20' long and located in a wire bundle in the bilge. This feeder conductor was connected directly to the battery switch and the only protection was on the power panel. In the event the old insulation failed, and there was a short circuit to ground the conductor would melt down, possible causing a fire and the loss of the boat and possibly lives.
Sorry to contradict you Frankly.
Bill in JB
Quadrille in JB is offline   Reply With Quote
Old 24-06-2021, 04:10   #6
Registered User

Join Date: Mar 2019
Location: I'm in Johannesburg, boat in Cape Town :(
Boat: 1986 Bruce Roberts 45 raised saloon
Posts: 220
Re: Is AC feeder bus ok to use?

Frankly is correct in that short circuit and fault protection must be located at source, overcurrent protection can be anywhere along the cable.

Note that to follow this advice would require double protection, most people would elect to have a single protection device which is short cct/fault current/overcurrent rated.
markcouz is offline   Reply With Quote
Old 24-06-2021, 05:40   #7
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 813
Re: Is AC feeder bus ok to use?

Just trying to encourage a little electrical understanding to go with all the knowledge that is dispensed around here (somebody once said understanding was more valuable than knowledge).

Most are struggling with 30 YO designs with with modern electrical requirements. Understanding can sometimes reduce the work load. Obviously does not apply to your bilge pump situation.

I just practice physical separation of wiring components (where practical) as the ultimate short circuit/ ground fault solution.


Frankly
Frankly is offline   Reply With Quote
Old 24-06-2021, 08:05   #8
Registered User

Join Date: Mar 2015
Posts: 734
Re: Is AC feeder bus ok to use?

Quote:
Originally Posted by Frankly View Post
Just trying to encourage a little electrical understanding to go with all the knowledge that is dispensed around here (somebody once said understanding was more valuable than knowledge).

Most are struggling with 30 YO designs with with modern electrical requirements. Understanding can sometimes reduce the work load. Obviously does not apply to your bilge pump situation.

I just practice physical separation of wiring components (where practical) as the ultimate short circuit/ ground fault solution.


Frankly
NO a protection device (breaker) close to the power source is the ultimate solution, separation is just prevention.
guyrj33 is offline   Reply With Quote
Old 24-06-2021, 08:14   #9
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 813
Re: Is AC feeder bus ok to use?

I will take 4" of separation between positive and negative over a circuit breaker/ fuse any day of the week and twice on Sundays.


Frankly
Frankly is offline   Reply With Quote
Old 24-06-2021, 08:17   #10
Registered User

Join Date: Mar 2015
Posts: 734
Re: Is AC feeder bus ok to use?

Quote:
Originally Posted by Frankly View Post
I will take 4" of separation between positive and negative over a circuit breaker/ fuse any day of the week and twice on Sundays.


Frankly
How will that help when the device at the end of the run short circuits and overheats your wire run? That wire is still inside your very combustible boat.
guyrj33 is offline   Reply With Quote
Old 24-06-2021, 09:19   #11
Registered User

Join Date: Sep 2020
Location: Im swimming in the Atlantic Ocean right now.
Boat: Approx 25 ft of blubber and muscle with big fins / natural selection- current state of evolution
Posts: 166
Re: Is AC feeder bus ok to use?

Thanks for all the replies. Iv'e been pretty busy past couple days and havn't had time to read/respond. Will try and do this now.

I've attached a crude diagram of my intention/thinking regarding how i was considering wiring everything to make it easier. I am also learning about cable branching using small fuse blocks which may help me consolidate some items and save space on the panel.

My current setup (see pic) will be a single AC sub panel thats fed from an ELCI breaker. In the end I may end up with three battery chargers when the final upgrade is complete later this year. I figured the three chargers would be on a seperate sub panel, i would have the one currently installed (in pic) and possibly a third depending on what devices i end up with in the final upgrade, but also to allow for future expandability. So in the end i could still end up with three seperate AC sub panels.

Based o my current rats nest and pics i've seen of nicely done electrical upgrades, it seems easier to run all the wires from the loads to bus bars and terminal blocks when possible just to make it easier to remove the panel and trouble shoot wiring issues when they arise, but i havn't seen anyone run hots from a single bus bar to multiple sub panels yet so thats why i was curious if its ok to do, and asking. I am working with 30Amp shore power and am very careful about managing loads for what thats worth. I wonder if adding too many panels is just asking for trouble if/when i have guests aboard who aren't?

Everything would be covered and carefully placed so there was no possibility of wires coming into contact with each other or something they shouldn't.
Attached Thumbnails
Click image for larger version

Name:	AC Wiring Diagram.jpg
Views:	31
Size:	363.7 KB
ID:	240973   Click image for larger version

Name:	IMG_0037.jpg
Views:	21
Size:	415.5 KB
ID:	240974  

BAD ORCA is offline   Reply With Quote
Old 24-06-2021, 09:38   #12
Registered User

Join Date: Sep 2020
Location: Im swimming in the Atlantic Ocean right now.
Boat: Approx 25 ft of blubber and muscle with big fins / natural selection- current state of evolution
Posts: 166
Re: Is AC feeder bus ok to use?

Quote:
Originally Posted by rslifkin View Post
I'd be inclined to put in a small panel instead with breakers feeding each sub panel. If nothing else, it allows turning off just 1 sub panel for service.
Thats an interesting idea. Thanks.
BAD ORCA is offline   Reply With Quote
Old 24-06-2021, 09:43   #13
Registered User

Join Date: Sep 2020
Location: Im swimming in the Atlantic Ocean right now.
Boat: Approx 25 ft of blubber and muscle with big fins / natural selection- current state of evolution
Posts: 166
Re: Is AC feeder bus ok to use?

Quote:
Originally Posted by Frankly View Post
If I understand correctly your question, I think providing a small terminal strip to distribute power to several sub panels would be preferred to stacking a bunch of feeders/ lugs on a breaker stud. Just be sure the TS/ wiring is rated for the main breaker (probably 30 A) and secure and separate the hot leads from the grounds and neutrals if practical.

As I have repeated numerous times, a conductor can be protected from overcurrent any where along its length (beginning or end), protection against short circuits and ground faults at the source. Physical separation also works in the short circuit and ground fault condition.


Frankly
Thanks, Blue Seas recommends #10 in my situation, I was leaning towards #8 just to give me a little extra margin but main breaker is 30Amp ELCI.
BAD ORCA is offline   Reply With Quote
Old 24-06-2021, 10:53   #14
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 813
Re: Is AC feeder bus ok to use?

Quote:
Originally Posted by guyrj33 View Post
How will that help when the device at the end of the run short circuits and overheats your wire run? That wire is still inside your very combustible boat.
Not saying no overcurrent protection is needed just that it can be located anywhere along the circuit and short circuit and ground fault conditions are taken care of by separation (if there can be no contact between conductors or conductors and ground there can be no short circuit or ground fault).

A little off the OP but take the situation we all face when we put a battery on a boat. ABYC says 7" max before protection. If a reasonable arrangement is a couple of feet of wire to a battery switch, then short distance from switch common to a main fuse it can be perfectly safe if one takes the trouble/ planning to physically isolate these conductors from the battery negatives and or grounds. ABYC compliant nope, electrically safe an emphatic yes.

I have been at this stuff for over 50 years (30 for the US Navy, and 15 in private practice). Circuit protections usually works but I have seen all means fail and usually under high current fault conditions. These big battery banks (particularly Lithium) just make the situation worse.

Yes I know about battery terminal fusing, also seen excessive voltage drop using the SS screw connections vice the old lead post.


Frankly
Frankly is offline   Reply With Quote
Old 24-06-2021, 13:29   #15
Registered User

Join Date: Oct 2018
Location: Dallas, TX
Posts: 383
Re: Is AC feeder bus ok to use?

Are you just daisy chaining the hots but home running the neutrals? I don't know if AFCI is used on a boat or marinas but if you end up sharing neutrals between circuits it can trip AFCI breakers.
NPCampbell is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LiFePO4: charge bus, load bus, buffer battery s/v Jedi Lithium Power Systems 3 07-07-2020 16:19
Furler Feeder Height Above Tack akio.kanemoto Deck hardware: Rigging, Sails & Hoisting 3 07-09-2011 01:02
ABYC Power Feeder Code E-8.11.4.1 vs E-8.11.9.2.1 sdowney717 Electrical: Batteries, Generators & Solar 27 09-07-2011 09:47
Cable Size for AC Grounding Bus to DC Neg Main Bus ? Beausoleil Electrical: Batteries, Generators & Solar 1 26-10-2010 11:19
Petersen twin foil feeder... Weyalan Deck hardware: Rigging, Sails & Hoisting 1 01-04-2008 15:12

Advertise Here


All times are GMT -7. The time now is 17:31.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.