Electrical Safety with Existing Wiring - aka help me to not electrocute myself

[bkrunaway]

Hey team, 

My goal tomorrow is to rip out the plywood and fabric walls of my van and take out the fiberglass insulation that one of the previous owners put in. I feel confident about removing the walls and insulation, but I am a little worried about messing with the existing electrical system as I do so. There is a plug outside for shore power and the wiring may also be hooked up to the starter battery/alternator but I am not sure yet. 

A few questions re ELECTRICAL SAFETY: 

1. Am I only at risk of shocking myself if the car is on? Or is the starter battery always able to send a current to the outlets in the back of the van?
2. How can I insure that the system is not live before messing with the outlets, fuse box, etc?

Any pointers about navigating an existing electrical system would be appreciated!





Not much there yet, but you can check out my build thread here: http://www.cheaprvliving.com/forums/Thread-Scout-the-Van-95-Dodge-Ram-High-Top

 

[tx2sturgis]

Wow....I had to figure things out by looking at the build thread and trying see what the plan is.

Ok...

First, 12 vdc wiring will not shock you...But you do need to power off the circuits you are working on since accidentally shorting live wires together is bad. So you need to figure out what is live, if anything, on 12 v back there even with the ignition off. There might be some dome lights that have power continuously, but I have no way of knowing, you have to test them.

It looks like the baseboard space heater was either powered (on AC 120v) from shore power or a genset, but you havent found a genset so lets assume there isnt one, and even if there was, it would not be powering anything unless it was running, and you'd know if it was. There MIGHT be 12 volts still supplied to that genset switch, so be careful working around it.

If the van is not hooked up to shore power, with an extension cord to an outlet, then you have ZERO electrical power to the heater. There is no chance in hell that a previous owner ran power to that space heater from the starter battery, since it simply would never work on 12 volts.

So, yes, it would be safe to work on...or cut or unhook the wires and remove it, along with the breaker box. It looks like they are in bad shape anyway.

 

[WalkaboutTed]

I'll talk in generalities from a former electrical newbie to a new one. It's fairly difficult to shock yourself with 12 volts in the low amperage most of us are using. Given that, I've made a couple impressive showers of sparks (albeit with 300 ah of batteries). Just fuse everything. It will give you peace of mind.

If you don't have a master on/off switch, perhaps that could be your first item to install. Get yourself a multi meter and it will be your friend and reduce your mistakes (and you can make sure a wire is dead, too) . And for me, the best investment of time was labels. I labeled each end of the wire and in the middle, wherever I thought I might need it in the future. Diagram what you have and what you do in the future-otherwise you'll forget and cause yourself extra work, following each wire.

Depending on what you find, perhaps you might need to install a parallel system or install new. Often, the wiring that comes with a vehicle is barely adequate at best or even substandard.

When I started our van project, I read...and read...and read. I went through too many threads on this board to count. I also got a book, "Sailboat Electrics Simplified". That book made it very simple with lots of pictures. I started with knowing that I wasn't going to electrocute myself with 12 volts, unlike 120 volts. I went on from there. I'm an old lady, and if I can do it, anyone can!

Have fun!
Ted

 

[bkrunaway]

Brian, thank you so much for helping me start to get a handle on this and for checking out my build thread to get the background.

Here's a bit more information:
---The dome lights are all powered continuously, I can switch them on and off when the ignition is not on.
--The outlets will not charge my phone when the fuse box is switched on or off. (This was my very amateur test to see if there was current flowing to the outlets.)

Thanks for the information about the heater.

The fuse box though, how can I be sure that it does not have live wires connected? Is it because a fuse box would be used only if there was another source of power in addition to the starter battery?

Thanks again!

 

[bkrunaway]

Thanks Ted! Especially for the book recommendation. My research is coming along and hopefully by the time I get to wiring I'll have a better sense of it. For now at least I've had a pep talk ensuring me that I will not fry myself before I've even gotten started!

 

[tx2sturgis]

Brian, thank you so much for helping me start to get a handle on this and for checking out my build thread to get the background.

You bet, I'm here to help.


There are two distinct and separate systems back there. 12 volts DC, running the dome lights and maybe a cigarette lighter port or two, and the other system is 120 volts AC, like you have in your house, for the heater, fed thru the breaker box.

12 volt wiring is the thin automotive wiring run in bundles, usually in the frame and body of the vehicle.

The 120 volt wiring which was added by someone, is the thick romex you see running into the breaker box. The two types of wiring will not be interconnected.

The romex will have no power to it unless you are hooked up to shore power (extension cord to a house or garage outlet).

That breaker box and heater can not be hooked to the 12 volt system, period. They will only receive power either thru a shore power hookup, or an inverter, (I didnt see one) or a generator (a genset).

If none of those are present and working, there is no power to the outlet, the heater, or the breaker box.

 

[LoupGarou]

Regarding 12vdc, disconnect the positive cable to the battery and you'll be fine.

 

[Weight]

Negative! Disconnect the negative cable from the starter battery and the house battery if you have one. Always disconnect the battery negative first and then the positive. Install the positive first and last the negative. Get yourself a inexpensive combination meter (volt-meter). Harbor Freight has one available with their free coupons. The leads are not that good, but they work. But you can find meters for less than $10 and $20. Always disconnect the negative battery connection before working around wires. No shock, but the fire can start quickly. And do not plug the shore cable into any outlet.

 

[LoupGarou]

"Negative" is correct.

Wouldn't hurt, no pun intended, to remove rings, watches, necklaces and bracelets when working on anything electrical.

 

[bkrunaway]

Thanks again Brian for more great information! Super clear description. Since it's raining today I'm going to do some more reading. So far I've been searching the build threads and other forums for answers to specific questions, but I think Im going to take this rainy day to just start reading them beginning to end and take notes.

Thanks @weight thought that's what it would come to to work on the dome lights, etc.

It's raining pretty hard here today so brought Scout (the van) in for her inspection and to take care of an exhaust leak. Hopefully will tackle the gutting tomorrow or Wednesday.