Lights flicker when furnace is on - Page 2 - Fiberglass RV


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Old 05-02-2011, 07:45 AM   #15
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Originally Posted by P. Raz View Post
ThomasE, my guess is you are seeing battery loading, a reduction in battery voltage due to higher current demand. Any increase in circuit current will cause a drop in battery voltage. Put a voltmeter on the battery and take note of the voltage as various things are turned on and off. Loading effect is more pronounced with an aging battery. Bad connections tend to draw less current not more so I don't see how a bad connection anywhere other than the light circuit itself causing the lights to dim. Please let us know what you find, Raz
Obviously, the more "demand" that is placed on a battery (or any power source for that matter), there will be a relationship between the demand of the total cumulative "load", and the power sources' ability to meet that demand. It makes no difference whether the load is on the same circuit or on another circuit, the demand for power from the source (in this case, the battery), will be cumulative for ALL the loads being supplied.

Comparative analogy to visualize how electricity functions (as compared to a water system):
Voltage = think of it as the water pressure.
Amperage = think of it as the flow (i.e. gallons per minute).
Resistance = think of it as rusty pipes or undersized pipes.

I agree that poor connections do demand less current (amperage), but they also do require a higher voltage (electromotive force, or "pressure" if you will,) to overcome the increased resistance. If your voltage (pressure) is already marginal to begin with, any cumulative load (opening more faucets, thus increasing the flow, or "gpm") placed on that weak battery will result in a diminished ability to supply sufficient voltage to meet the demand.

Resistance, or the restriction of the flow so to speak, will require more force (voltage) to provide the same level of flow (amperage) to meet the demand. Resistance is not just found in wiring, appliances or connections, but also internally inside the battery as well. If this internal resistance becomes too much for the flow demanded (such as in a bad or severely deteriorated battery), then it would require extra voltage (pressure) to overcome this resistance, a condition which it obviously cannot meet. When it can no longer keep up with this demand, the flow comes out as a dribble instead of a strong stream. This is why your lights dim. It's not how many hoses you have, it's how many you have turned on at one time, and how much of a flow they each put out.

I don't know if I can make it any simpler than this either... Hope it helps you to understand the relationship between all the "players" here.
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Old 05-02-2011, 02:29 PM   #16
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OK I think I figured out where the bad connection is. The main +12v line from the battery connects to a fuse block, that fuse block is the old style glass fuse type. The clips that hold the fuse in place is riveted to another metal block that you can insert the wire into and tighten a screw to hold the wire in place. The connection between the fuse clip, and the block holding the wire was loose since the only way it was held on was with a small rivet, I think this is a bad design. I temporarily bypassed the fuse block with an inline fuse holder, and the flicker is gone when I turn on the furnace. Not only that, but when I turn on the water pump, the lights now barely dim.

But I'm not done yet, I really hated that glass fuse block because I already had another problem on a different circuit with that type of clips. I got some ATO fuse blocks from Kragens, I've taken out my power supply and ripped off that old glass fuse block, and installed the ATO fuse block. I need to pick up a few more connectors tonight to finish the job.
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Old 05-04-2011, 02:22 PM   #17
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I replaced the old glass fuse block with a new ATO fuse block and all is well now. The culprit was a bad connection for the fuse clip of the +12v line coming from the battery. The lights and furnace are on different circuits, as is the water pump. But due to the bad +12 connection at the fuse block, having multiple things going at once likely dropped the voltage enough to get my LED lights flickering.
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Old 05-05-2011, 12:26 AM   #18
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Originally Posted by Casita Greg View Post
Neither AC nor DC wiring should be using the frame for a return path for any branch circuits. Yes, it will "work" after a fashion, in so much that it will conduct electricity, but it is a "lazy man's way" of doing things, can be potentially dangerous, and is totally wrong from a circuit design standpoint. It will only lead to electrical problems down the road, such as backfeed on other circuits, "ghost power vampires" that can drain your battery when you think everything is turned off, electolytic component corrosion, increased radio interference (static), etc. In short, a whole panoply of self-inflicted bugaboos can arise from this style of circuit design. All DC wiring circuits should be TWO wire, and ALL ground wires should come together (terminate) on ONE common ground bus bar or ground strip. This ground bus is then connected to the frame AT ONLY ONE POINT! This is also the same connection point used for any trailer bonding wire. Multiple circuit grounds made to the frame are a big no no, but it is more common than not. Many "home electricians" do not understand the relationship between a "grounding system" and a "bonding system". Although they both (ideally) terminate at ONE COMMON POINT on the chassis (frame), they are NOT INTERCHANGEABLE in their use or function. In summary, NEVER use the trailer frame as a return leg in any circuit.

Bonding systems are meant to provide a low-resistance path to ground for any heavy overcurrent loads, such as a lightning strike or a direct short in any bonded system component's casing or enclosure to prevent electrocution. Using the frame as a return path is not what a bonding system is designed to do.

Your AC wiring should be grounded to the frame at the same ground point as your DC wiring and your frame/electrical component bonding connection. Again, this should be the same point as your DC and bonding grounds (1 ground point only).
Hello-

I've been following this thread as best I can and have some questions related to the above post.
The first picture shows my (factory installed) converter, with 110v line. Two green groundwires are attached at the point labeled "equip. ground". The smaller wire is groundwire for the (added) charging unit in the foreground. The heavier wire goes through a hole in the floor and (2nd picture) is affixed to the trailer frame outside. The 110v circuit breaker is at the other side of the trailer, and I don't see any groundwire affixed to the frame in that area.
The tongue-mounted battery is connected at the converter (blue line in picture) and is (wrongly?) grounded to the frame at the tongue.
.................Click image for larger version

Name:	<a title=Trillium ground wires 002.jpg Views: 9 Size: 215.7 KB ID: 35674" style="margin: 2px" />.....Click image for larger version

Name:	<a title=Trillium ground wires 001.jpg Views: 11 Size: 271.4 KB ID: 35675" style="margin: 2px" />
My Questions are:
1) Is the single ground you refer to the heavy green ground shown above?
2) If so, does it serve as ground for all electricals including 110v.?
and
3) If the battery is incorrectly grounded to the trailer tongue, should I run it all the way back to the connection point shown in 1st picture?
OR
.....b) The picture below is the factory installed pigtail-to-trailer wiring connection point at front of trailer. Should I attach the battery groundwire here? What the heck am I looking at here, anyway? There are two 15a fuses in that interconnected bundle. Is this the point at which both battery connections should have been made in the first place?

Click image for larger version

Name:	<a title=Trillium front wires 002.jpg Views: 9 Size: 277.0 KB ID: 35673" style="margin: 2px" />

Thanks, I hope.

Francesca
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Old 05-05-2011, 12:06 PM   #19
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Hi Francesca,
From what I was able to trace out from viewing your photos, it appears that your large green wire is your main ground to the frame. It appears that all your other grounds (converter, charger, and 120vac ground lines) seem to eventually terminate (as best I can tell from your pics) into the same heavy green wire connected to the frame (photo #2) where it comes through the floor. This does appear to be the point where all your ac and dc grounds come to one point, which is good. Of course, you would have to check your individual branch circuits to see if any "aftermarket" installations were "shortcut grounded" to the frame elsewhere in your trailer, as mods may well have been made over the years. This would require an actual "look-see" and visual wire trace to ascertain that they were properly grounded to your main ground bus.

I'm not entirely able to make out what the two 15 amp fused circuits go to from viewing the photos, but as far as your trailers' battery ground point goes, if you feel up to making the change, I would offer a suggestion to remove the presently attached battery ground from where it is now on the tongue, and run a new line from the negative terminal back to the ground point shown in your photo (where the big green wire hooks to the frame.)

Hope this helps.
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Old 05-05-2011, 12:25 PM   #20
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Originally Posted by Casita Greg View Post
Hi Francesca,
From what I was able to trace out from your photos, it appears that your large green wire is your main ground. The grounds seem to terminate (as best I can tell from your pics) into one heavy green wire to the frame (photo #2) where it comes through the bulkhead.
Thanks for getting back!
Should I connect the battery ground at that point?
Or-
The battery install is ours- the trailer had never had its own before we got it, and my partner in crime (a double-"g" Gregg!) was more or less winging it with the install. He ran the wire all the way back to the converter, and it was a struggle to fit the heavy wire through the knockout with all the other wires. Now I'm wondering if both battery connections can be made at the harness shown in the third picture???
Sure would be simpler...

Thanks again,

Francesca
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Old 05-05-2011, 12:46 PM   #21
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I think that it would be a pretty safe assumption that the two heavy black wires are main feeds to something (what exactly I can't tell from the photos), since they are both heavy wires, black, and are fused. Perhaps you may want to consider installing a small heavy-duty terminal strip. You can find nice ones generally at one of your local boat/marine suppliers. Get one with one large terminal lug for the heavy battery (+) hot leg to connect to, and having several screw terminals, (fused ones are nice,) for distributing battery power to all of your subordinate circuits in your trailer. Run the battery (+) positive to feed the terminal strip, and the battery (-) negative back to the frame ground bolt with the heavy green wire.
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Old 05-05-2011, 03:59 PM   #22
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Quote:
Originally Posted by Casita Greg View Post
Hi Francesca,
From what I was able to trace out from viewing your photos, it appears that your large green wire is your main ground to the frame. It appears that all your other grounds (converter, charger, and 120vac ground lines) seem to eventually terminate (as best I can tell from your pics) into the same heavy green wire connected to the frame (photo #2) where it comes through the floor. This does appear to be the point where all your ac and dc grounds come to one point, which is good. Of course, you would have to check your individual branch circuits to see if any "aftermarket" installations were "shortcut grounded" to the frame elsewhere in your trailer, as mods may well have been made over the years. This would require an actual "look-see" and visual wire trace to ascertain that they were properly grounded to your main ground bus.

I'm not entirely able to make out what the two 15 amp fused circuits go to from viewing the photos, but as far as your trailers' battery ground point goes, if you feel up to making the change, I would offer a suggestion to remove the presently attached battery ground from where it is now on the tongue, and run a new line from the negative terminal back to the ground point shown in your photo (where the big green wire hooks to the frame.)

Hope this helps.
Hi Francesca,

While I agree that having a single ground point for both 110V and 12V circuits is perfectly fine, for a small trailer it is also fine to have your 110V grounded to the trailer frame at the converter and your 12V grounded to the trailer frame close to the battery. This is the factory install way for my 1980 Trillium 4500, and my email to Trillium RV last fall (found on another thread here: Trillium trailer 12V wiring ) confirmed that it is correct. It is not the only way to do it, but it is not a fault to do it that way.

When wiring a house or large building, it is important to have everything grounded to the same place because real grounds (the kind that are a stake pounded into the earth) vary in their actual level from point to point even around a house and having two different grounds can create a "ground loop". However, the 6 foot or so difference in a trailer makes no electrical difference at all in a metal trailer frame. In fact, I would personally prefer to have the large metal frame of the trailer carry the ground between the two points rather than run a wire back to the ground point, but either way works as long as the connections are good.

To be clear, we are talking about the ground wires, usually green, not the negative (return) wires which are usually white in these trailers. The negative circuit return path must have its own wires, not try to run through the grounding.

My two bits worth.
Rick G
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Old 05-06-2011, 10:39 AM   #23
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To begin with, while in normal use, your trailer isn't grounded at all unless:

* You physically drive a "ground rod" into the earth and attach a conductor from the frame to it, or to a metallic pipe in the ground, when you get to your campsite in order to physically create a bond between the trailer frame and the ground, or

* You hook up to a shore power source which is equipped with a ground wire (this also rules out being grounded if you are running off a portable generator too, unless you grounded the generator to earth as well.)


While I agree that having a single ground point for both 110V and 12V circuits is perfectly fine, for a small trailer it is also fine to have your 110V grounded to the trailer frame at the converter and your 12V grounded to the trailer frame close to the battery. This is the factory install way for my 1980 Trillium 4500, and my email to Trillium RV last fall (found on another thread here: Trillium trailer 12V wiring ) confirmed that it is correct. It is not the only way to do it, but it is not a fault to do it that way.

Actually, while the automotive industry (including RV and trailer manufacturers) use the vehicle chassis as a "ground" or return path AKA negative ground, it doesn't mean that it is the best design. Steel is a relatively poor choice for conducting electricity when compared to say copper. It takes a whole lot more steel to provide the equivalent reduction in electrical resistance as copper wire. Vehicle frames provide, for the most part, a low enough electrical resistance to get away with using it as a return path. Doesn't mean it is the best way, it means that the industry SAVES MONEY by not providing a negative wire back to the battery for every item.

To be clear, we are talking about the ground wires, usually green, not the negative (return) wires which are usually white in these trailers. The negative circuit return path must have its own wires, not try to run through the grounding.

Just because auto and RV manufacturers do something, doesn't mean it is a good thing to copy. As you mentioned it above in your post Rick, I know you have heard about "ground loops." For those who may not be familiar with this phenomenon, in the audio world it is a nightmare, it causes buzzes, hum, pops and clicks. It comes from small differences in voltage due to poor grounding between devices. Ideally all electrical devices should have the same exact negative ground potential. This is where the negative ground bus comes into play.

In the RV world, since 12V is treated as "low voltage" wiring, the general practice is to have one 8 gauge negative ground wire to exit the converter panel and it meets with all the 12V negative grounds from all the 12V items. Typically the RV manufacturer will bundle all the wires together with a very large wire nut. If you are lucky they may have used a crimp instead. This is garbage, not all the wires will make a good connection. A much better way to do this is to provide a negative bus bar, upon which, each individual wire is physically attached securely to the bar.

A vehicles' 12V wiring is a bit more critical when it comes to voltage drop when compared to 120V. A value of 5% is typically the largest acceptable voltage drop for 120V, but with 12V that is too much of a voltage drop. In a 120V circuit, 5% drop is 6V but 12.5 V circuit, a 5% drop is .625V which is a very large amount of drop when comparing 120V to 12V. (Remember, 12.5 V = good battery, 12V = dead battery)

With 12V wiring it is better to keep your wiring runs as short as possible, and use a heavier gauge wire to keep the voltage drop as little as possible.







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Old 05-06-2011, 12:53 PM   #24
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Here's the wiring diagram Rick posted in the thread at Trillium trailer 12V wiring Is the "return wire" the line that leaves the negative battery post, splits to a ground point, and eventually ends up at the negative terminal on the converter?

Francesca

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Old 05-06-2011, 01:26 PM   #25
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In a word, yes...
Now the long version...
The battery negative lead, which is also hooked to the frame (ground) appears in the schematic to be providing separate grounds for all the various 12 vdc appliances. Whether they are "T tapped" into existing wiring runs, wired all the way back to the converter ground bar, or are just grounded to the frame is not really determinable from the line diagram schematic, as the drawing only represents current paths returning to ground. I can't tell if current is returned by wire all the way back to the converter, or just screwed to the frame as a return leg for the circuit. Either would show up on the drawing as "returning to ground", it's just not clear how they actually accomplished that action. You would have to visually determine if there are indeed separate wires (+ and -) running to and from any appliance and the converter and battery terminals. Although either way will function, using the frame in lieu of an actual return conductor (aka wire) isn't the best way to hook things up (as I mentioned in my previous post). Just tying all these various return leads together is not a good way to do it either. I would suggest installing one common ground bus to terminate all the individual branch circuits to one common grounding point, but this is definely a lot of work which you may, or may not, feel up to undertaking. Not saying that using the frame won't work, it's just not a good way to wire things up.
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Old 05-06-2011, 01:47 PM   #26
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I think dawn is starting to break
I'm going to cogitate on all I (might!) have learned and make an examination of my existing-er-"system".
I'm sure I'll be back in a day or two with more questions...
I'll be most grateful if you stay tuned to this thread!


Francesca
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Old 05-06-2011, 01:55 PM   #27
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Talking

We're here for ya!
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Old 05-16-2011, 02:20 PM   #28
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Quote:
Originally Posted by Casita Greg View Post

To be clear, we are talking about the ground wires, usually green, not the negative (return) wires which are usually white in these trailers. The negative circuit return path must have its own wires, not try to run through the grounding.
Hello again!

I've actually lost track of who said the above first, but it does seem to be -uncontroversial
I'm still a bit hazy about this- my Trillium has two heavy wires, black and white, that connect from the junction up front under the bench to the converter.
Is the white wire the "return" by which 12v power is-well, returned to the battery? Can I call it a "charging line?
Both my black and the white wires are connected to the converter, which has the Main Trailer Ground connection to the frame.
There is no green wire between these two points.

Am I grounded? (side note: I'M NOT TALKING TO YOU, MOM! )

Thanks for everybody's patient help!

Francesca
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