| Author |
Message |
S'Coolbus nut
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 20, 2005 - 11:07 pm: | |
First of all, I am not going to use the extension cords that I found such a great deal on!
I decided that it's just not worth the risk of some future problem, just to save a couple of bucks. I really didn't know there was any difference in the type of wire.
So here is the question. I am going to order some spools of wire (got my Waytek catalogue, thanks for the tip).
What Ga wire do I need to run?? I was planning to use 12 Ga, but found that some here are using 10Ga, even 8 Ga.
Why?
I want good service life with no problems, but I can't see the need for such big wire.
That being said, I will go with whatever is the most reccomended.
Next question - What is the reccomended method of grounding your 12v circuits? Do any of you run all the ground wires back to the load center? Or are you just grounding to the bus body?
If running grounds back to the load center, a jacketed two wire cable would seem nice to work with.
Should the ground wire be as heavy as the hot wire?
Thanks very much, guys
Mark
S'Coolbus Nut |
Brian Brown (Fishbowlbrian)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 20, 2005 - 11:52 pm: | |
You need to know the max. load on the wire to size it. You also need to know its length to account for voltage drop (in DC wiring, count the "round trip distance if you do run two wires). You'll run into a real problem (crispy coach) it you under-size the wire to its load and especially to its fuse. The fuse must be rated less than or equal to the max. ampacity you'll have running in the wire.
There's no harm going with a bigger wire than required, though it might be more expensive and less flexible.
Considering chassis corrosion, etc., you might want to run two-wires when practicable, or maybe gang up your grounds and tie them off together on a grounding block to tie to the chassis in common locations.
Considering the safety issues involved, I'd suggest you go to the library and read up on elec. wiring concepts before running any circuits.
HTH,
Brian Brown |
James Maxwell (Jmaxwell)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 21, 2005 - 12:09 am: | |
I 2nd everything Brian has told you. For grounding, I use the 2nd method suggested by Brian. Whichever, do not rely on point of service chassis grounding. |
james dean boggs (Jd_boggs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 21, 2005 - 12:22 am: | |
This has a table which provides the max amps, wire gage and voltage drop per 100 feet.
http://www.powerstream.com/Wire_Size.htm
http://www.alphawire.com/pages/315.cfm
Some coaches place the power switch on the NEG pole of the battery. Check this on your coach then decide where to attach a heavy wire gage for the NEG pole. On my coach I used #4 welding cable to bring the NEG to my refrigerator, water pump and 1000 watt inverter. Try not to use the coach chassis as the ground. Bring a cable from the NEG pole of the batteries.
Good luck. |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 21, 2005 - 5:46 am: | |
Every DC item works best with the highest Voltage you can give it.
Most tables are for 3% (best ) or 10% Voltage drop.
Simplest is to find a source of bigger wire ( I use # 10 ) and simply wire all the small loads with the same wire.
Less V drop , and your not "cast in stone" so can use a different DC item if a change becomes necessary years later.
For an inverter / charger use the biggest you can find , oversize has no penalty on performance.
FAST FRED |
Phil Dumpster
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 21, 2005 - 10:42 am: | |
Not only that, but bigger wire and less voltage drop means less power lost in the wiring and less heat generated, which can be quite important when the wire is run in a confined space. Not to mention the effect this will have on the life of your house batteries.
Voltage drop occurs in all wires. It's a function of the current through the conductor and the length of the conductor. In 110 AC circuits it isn't that big of a deal because the current is relatively low, and in many automotive applications the run just isn't long enough to make it a problem. In a 40 foot bus, however, it becomes an important consideration.
The price difference between 12 gauge and 10 gauge isn't that great. Pay the extra and get the larger wire. |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 21, 2005 - 12:48 pm: | |
and....it depends what the wire is going to....if it's one light 12ga. is fine...if it's going to something high draw ...like a motor 10 ga.is better...also the longer (run) between supply (battery) and use (motor)...the heavier the wire needs to be |
CoryDaneRTS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 21, 2005 - 11:55 pm: | |
You need to use the charts for the length of the wire. West Marine has a good one.
The longer the run (in feet) the larger the wire has to be, similar to thinking of the larger the load, the larger the wire.
Another factor will be the load. If you have a large load at the end of a 40 foot length of wire, the size needed is even bigger.
Now aren't you glad you got involved inthe conversion wiring??????
Use the charts, they will be a good guide. you may care to over size if the cable does not get too bulky to pull.
Because of the charactoristic of DC, length of wire is very important to the voltage you want at the other end.
AC has a different charactoristic and is a bit more forgiving, though I would keep the sizes standard between the ac/dc incase sometime in the future a cable may change from ac to dc or vice versa.
Its all loading and voltage when you get down to the nity grity. AND of course SAFETY for you and your family.
Lionel Train Engineer
cd |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 22, 2005 - 12:33 am: | |
Amateur plumbers ruin your carpet...amateur electricians kill people. Hire a qualified electrician and be certain he uses the National Electrical Code...especially Article 551. At the very least get constant guidance from the Code and his skills. Anything less is dangerous and irresponsible. ...JJ |
s'Coolbus nut
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 22, 2005 - 2:06 am: | |
THANKS, guys!
I always wondered why DC wiring needed to have the larger wire sizes. (voltage drop, overheated wires, crispy RVs...)
Thanks for the link to the wire size calculator, JD Boggs! Very useful!
As always, thanks again to all for your advice and comments. However, (jayjay), I'm NOT going to hire an electrician to do a job that I plan on doing myself!
That's why I came here to ask the question in the first place! ...CHILL, DUDE |
Pat Bartlett (Muddog16)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 22, 2005 - 8:33 am: | |
I agree with John, anyone who uses extension cords to wire anything permanent is putting their family at risk, if you don't know what you are doing when it comes to electrical installation, hire some one, or get a friend that does to help you, YOU PUT YOUR FAMILY AT RISK when you don't know what your doing, with electricity. |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 22, 2005 - 11:14 am: | |
Hey, this gives me an idea...
As you know, the emotional attachment to the first conversion gets in the way of the rational decision that one should cut and run, and start a new one with what one learned by screwing up on the first....
So, those who do poor wiring need to hook up with those who can't bring themselves to sell....
park close alongside at a rally....
Turn everything on and wait for the fire...
Insurance and civil courts will pay for the new conversion, the onlookers will learn the lesson about poor wiring, and be careful who you park next to, if you've got your coach the way you want it!
yes, I'm avoiding doing something else at the moment...
happy coaching!
buswarrior |
Doug Dickinson (Dougd470)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 22, 2005 - 12:20 pm: | |
Coolbus nut
I think you are headed in the right direction. Don't let the nay sayers distract you. Learn everything you can, read all the material, ask questions, and you will probably make a good decision based on facts. If you don't feel comfortable with doing something, then call on some qualified help.
Works for me
Doug
St Louis MC9 |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 22, 2005 - 9:54 pm: | |
s'Cool...I want to be the payee on the new life insurance policy I will buy for you. I'll even spring for the extra for your wife and children. ...JJ |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 22, 2005 - 10:16 pm: | |
Cory Dane has the right information on wire size. However, all circuits are not equally critical. Voltage drop to a light is not too bad. My reading on trouble shooting in RV magazines leads me to suggest that you be very careful to provide a heavy wire to the refrigerator and the propane furnace if you use one. I have read of problems with voltage drop causing circuit boards to burn out in these appliances.
You can use THHN wire in conduit for your wiring. It is multitranded and available at home building supply stores and electrical supply houses in a variety of colors. I have found on my 23 year old conversion that the most common problems with wiring are at the conections, not in the wire itself. Get really good crimping pliers that can apply a lot of force and buy good connectors. All connections should be at a terminal strip in a box. No wire nuts or inline splices. Leave some slack in the box so the wire does not work too hard against the terminal and it is easy to do changes in the future. If you run conduit, run a large enough one or two instead of one. Pull several extra strings through and leave them for future wiring pulls.
Fast Fred will tell you that marine wiring is best and he is probably right, but really a bus does not flex and move like a boat. The air suspension really isolates the wiring from road shocks. My bus has had THHN for 23 years. Just make sure there are no places where a metal edge can scrape through the insulation with time. |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 23, 2005 - 9:03 am: | |
"but really a bus does not flex and move like a boat"
Huh?
Aside from -that- statement, the bus's interior walls, floor and
ceiling cavities get quite a bit hotter (and colder) than any boat's.
Using wire with substandard or otherwise less than ideal insulation
for the purpose intended, is as bad as using an insufficient gauge
for the power needed. |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 23, 2005 - 3:58 pm: | |
Thhn is NOT substandard. It is better insulated than a lot of what is used on boats and motorhomes.
The reference to flexing and moving was because most THHN is a little stiffer and has fewer strands than boat wire or automotive wire. If you are running to an engine that is moving on its mounts and vibrating, you will need all that extra flexiblitily. I do not believe you need it to run from one room to another in a motorhome or coach. The wires in those applications do not vibrate and flex continuously. |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 23, 2005 - 7:08 pm: | |
I would take into consideration, that the light wallboard and
the outlet boxes mounted to them, would certainly move and
vibrate with any movement of the bus and it's running engine.
I would prefer to use wire with insulation that is as flexible
as the wire it incases.....
However...... I doubt any stranded wire with decent insulation
would be a problem of serious concern, but if it can be afforded,
I don't see any reason not to use marine grade products. |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 23, 2005 - 11:49 pm: | |
John, the primay reason not to use marine wiring products in a motorhome, is that it is against the law. Article 551 NEC
THHN wire is used in indusrial applications on conveyor lines and manufacturing equipment that produce more vibration in a day than a bus will see in a lifetime, and virtually ALL splices are done with wire nuts. Squirt them full of silicone caulk or SikaFlex 252, and they become waterproof too.
What are you going to do late some night when you pull in to a park and can't stay because your coach won't pass a Code Inspection, and it's 70 miles to the next park? To name a few I've seen...Spokane, Yuma, Las Vegas and Portsmouth,OH all have inspections at least part of the time. ...JJ |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 24, 2005 - 5:40 am: | |
"What are you going to do late some night when you pull in to a park and can't stay because your coach won't pass a Code Inspection,"
This is a great scenerio to justify horrable house wiring , THAT HAS NEVER HAPPENED!!
If you wire for SAFTY instead of cost/ avilibility just go to thye scrap yard and pull a RVIA shield from any scrap RV.
Install it and you will NEVER be asked , but should the impossable happen , you just point at the RVIA plate.
Marine wiring , cause MY life depends on it.
Works for me,
FAST FRED |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 24, 2005 - 7:24 am: | |
JJ-
LAW? It isn't "LAW", it's a code; an outline that was designed
to point to the "best way" to do something. Unfortunately, those
that promote the "code" do not always listen to the engineers
they've asked for advice from, to design and promote such "code".
LAW..... good grief..
And an RV "code inspection". ..? HAR HAR HAR!
Man.... you just gotta' stop smokin' dat stuff.
Oh..... and that "code" tells you the minimum they feel is proper,
using a better grade is always better. And when "codes" start
telling you -have to use- second best, we has gots us a real
dooozie of a problem.
Cheers man.... Don't drink and drive. That's a LAW. |
Sean Welsh (Sean)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 24, 2005 - 1:21 pm: | |
JTNG,
Sorry to break it to you, but sometimes a "code" does become a LAW (emphasis yours).
For example, with respect to fixed structures, all 50 states have adopted the NEC as LAW (with various specific exceptions or additions that vary from state to state). That means that you can be cited for violating the NEC, and even arrested in some cases. And, sorry, but code inspectors do not give *you* leeway to use a product that, in your opinion, is "better" than what the code requires -- it needs the opinion of a testing laboratory, such as UL. That is why the code requires "listed" materials.
That being said, the issue of adoption of the NEC into law as regards RV's is more ambiguous. Some states have adopted it, and some have not (explicitly). Of the states that have adopted it, some hold only professional manufacturers accountable to the standard, and some hold anyone who picks up a screwdriver accountable.
So if you convert a bus into an RV in one of these states, and you do not follow the NEC, you may in fact be breaking the law, and you may in fact be cited IF you are caught (big IF). Furthermore, even if you do so in a state that either does not have such a law or does not have any means to enforce it, you are prohibited by law from bringing that vehicle into many states that do. Again, it's unlikley you will be caught, but you would still be breaking the LAW.
This code argument comes up over and over again. It's unlikely anything I have written here is going to change your mind. Do it your own way. But people need to know what they are getting themselves into. It's hard to get away with telling an inspector that some guy on a bulletin board who does not use his real name and has no contact information said it was OK, so it must be.
-Sean |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 24, 2005 - 6:06 pm: | |
I find you amusing, Sean.
Actually, I find all your type of "the sky is falling" genre very
amusing.
Look to the "recall" sections of the web and let us know how
well the "code" and "law" prevents the "experts" from causing
harm to innocent and trusting citizens.
Common sense should always take precedence. Unfortunately,
too many like you, are of the mentality that some "code" or "law"
should force you to ignore the gift of your own common sense
in every instance.
Using marine grade wire in the bus may be overkill, but it's
the safest to use. The fact the RVIA or NEC does not "require"
the use in RVs does not mean it cannot be used.
You've been brainwashed, Sean. A puppet of pseudo-intellectual
masters. Amusing. |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 24, 2005 - 6:31 pm: | |
Incidentally, Sean......
If and when I ask for advice regarding the best way to do
something; the best type of device, wire, or plumbing
to use, I would hope that I hear what's worked best from
those that have experience using it, rather than some recital
of idle rhetoric regarding "what the code says".
And to tell you the truth, I think most of us "newbies" feel
the same way.
Aside from that, have a nice day. |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 25, 2005 - 5:32 am: | |
"I would hope that I hear what's worked best from
those that have experience using it, rather than some recital
of idle rhetoric regarding "what the code says".
You have just made 250 identical articles in BC useless ,
as ALL chant a mantra of "Code"
" Code"
" Code"
With little regard to reality.
Shame ,
FAST FRED |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 27, 2005 - 12:34 am: | |
With regard to flexibility: All of our house wireing and hopefully our bus wiring has the wire clamped or held in place and a short 6 inch or so piece of the wire extending beyond the clamp to the connection, switcy or whatever. Automotive type wiring frequently puts stress on the connector itself and the point where the wire enters the connector, without any really effective stress relief before that point. So in true automotive type connections, a much more flexible wire may be desireable. If we are designing our buses to last 30 or more more years, the wires should always be clamped, tie wrapped etc to relieve stress on the connections and Stranded home/industrial wiring like THHN would do fine. Probably solid wire would work fine too, because the stress is taken at a point not likely to fail. Still, I won't use solid wire. |
Brian (Bigbusguy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 27, 2005 - 1:10 pm: | |
"I would hope that I hear what's worked best from
those that have experience using it"
Here is some real time experience My 1968 24 foot travel trailer had solid romex wiring it.
Has any one ever taken a ride in a travel trailer its a ruff ride a lot harder on wiring then any bus would ever see.
I replaced all the 110 recipicals in it and pulled off one side panel to fix a dent and I can tell you the wiring looked 100% new. I never had any problems running 1500w heater in any out let.
SO will solid romex work yes would I use it? No its to hard to work with in the out let boxes.
Im also planning on not hiding any wiring in wall or places I can not get at.
I will probley run #12 THHN stranded type. And it will at last me.
Brian 4905 Klamath Falls Oregon |