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Author Topic: Electrical 101 - How do you run a new circuit?  (Read 4286 times)

skyking4ar2

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Electrical 101 - How do you run a new circuit?
« on: June 10, 2011, 10:03:14 AM »
I am not an electrician by any definition, and regret I am not better trained. However, I can follow directions, and can take a red wire to terminal A and and a black wire to terminal B. I get the idea of circuit breakers and loads and that's where my questions start.

Over the past year, we have learned about which circuits do what in the coach, can read the wiring diagram (kinda), and know what blows the breaker on the Xantrex inverter when it's dark, cold, and rainy out.  :'(

We have x number of breakers, and some of those circuits are not in use at the same time. That makes me think I can have total breaker capacity that exceeds the power available, but since they are not all on, it's not a problem.

I want to add another circuit so that when we plug in our electric heater, and the toaster or TV or something else is on, we don't pop the breaker for the general use circuit.

My thought is that the main panel has x amount of room for x number of breakers. If I have enough room there, I can add a breaker, run a circuit to a unique receptacle, and life will be good. I do not think the inverter comes into play, unless I don't understand it, because I don't think I can run the big stuff (A/C, washer, microwave) off the inverter anyway.

Am I on the right path here or is there something else I should be thinking about?
« Last Edit: June 10, 2011, 10:05:42 AM by skyking4ar2 »
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Re: Electrical 101 - How do you run a new circuit?
« Reply #1 on: June 10, 2011, 10:12:33 AM »
The total amperage of all breakers will almost always exceed the total amperage of the main breaker. If you try and run more amperage through the separate circuits than the main breaker can handle you will pop the main breaker. You can add as many circuits as you wish so long as each individual circuit is protected properly. Yes you can add a breaker and run a line to your heater. But as a retired electrician I would recommend you do not do the job yourself. Odds are you will not get it right even with very good directions. The National Electrical Code is very complex. It would be difficult to explain to you how to do it and follow the code so you don't burn up your RV. It would not cost very much to have an electrician do the job and then you would sleep better at night.

skyking4ar2

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Re: Electrical 101 - How do you run a new circuit?
« Reply #2 on: June 10, 2011, 11:01:25 AM »
Tom,

That's reasonable advice. I am a little apprehensive, though, given the many unusual experiences many have had with their technicians and their RV's. Should I be looking for some certification at one of the RV places, or is there an RV shop that specializes in electrical work, or ???

I suppose I need to start shopping that out. Being fulltime, I will really want to find someone who can accomodate us living in the rig and doing the work in a minimum amount of time. Does running that one circuit sound like a big deal?

Kim
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John From Detroit

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Re: Electrical 101 - How do you run a new circuit?
« Reply #3 on: June 10, 2011, 01:14:00 PM »
A lot depends on if it is a 30 or 50 amp rig.. I have added two circuits (well actually 4) to this 50 amp rig.. Two of them are very special and not often used so I won't mention them save to say they are "emergency power to the house" circuits, each 30 amp.

The two heater outlets are 20 amp.  One is on each leg (keep it balanced) and I did not worry too much aobout overloading the mains as well.. If I'm using heat. I'm not using ir Conditioning.

Now: If you have the room for a new breaker, GO FOR IT, if not you can get "Dual" breakes, not ganged 240 volt but two half width breakers (two that fit in one slot) they come in 15/15  15/20 20/20, 15/30 20/30 and 30/30 that I know of, Perhaps more.

I used 12GA wire for the runs to the sockets.. One is on a 15 amp breaker, the other a 20.> Both outlets are 20 amp type (The neutral is "T" shaped) and in proper boxes.  The wire runs directly from the breaker to the outlet, NO OTHER Outlets or devices.

Now many outlets in RV's use the cheap "push in" connections.. I bent wire around the screw and tightened well.

HOWEVER: I will caution here: If you do not know electrical wiring.. Find someone who does.. I mean there are still folks in this country who make house calls.. The fire department for example.
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Re: Electrical 101 - How do you run a new circuit?
« Reply #4 on: June 10, 2011, 01:35:47 PM »
Here's a thought, If you decide to do it yourself please have a qualified person check out your install BEFORE tripping the breaker on, or better yet, before terminating the wires. I cannot recall any electrician that has not made a mistake, and they are professionals. I bet Tom even has a screwdriver with an electrical arc burn on it.
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skyking4ar2

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Re: Electrical 101 - How do you run a new circuit?
« Reply #5 on: June 10, 2011, 01:53:25 PM »
If I'm using heat. I'm not using air Conditioning.

John, this is a 50 amp rig.

But the heat vs A/C invites this question: is there a way to split off the from the A/C circuit to run this heater? Or is it less complicated to just run another circuit? I won't be using both at the same time.

And to all who might be concerned, I don't connect anything to anything electrical that has not been checked out. And I wouldn't hesitate to check behind the electrician, regardless of credentials, either.
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seilerbird

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Re: Electrical 101 - How do you run a new circuit?
« Reply #6 on: June 10, 2011, 02:22:04 PM »
Here's a thought, If you decide to do it yourself please have a qualified person check out your install BEFORE tripping the breaker on, or better yet, before terminating the wires. I cannot recall any electrician that has not made a mistake, and they are professionals. I bet Tom even has a screwdriver with an electrical arc burn on it.
I never have arced a screwdriver. I was a house wireman for almost all of my career and we very rarely worked on live circuits. When I did it really got my attention. One hand behind my back, etc. I was only shocked twice in 20 years. Both times at home working on my own wiring.

The only mistake I can ever recall making is not becoming a full timer 20 years earlier.

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Re: Electrical 101 - How do you run a new circuit?
« Reply #7 on: June 10, 2011, 02:23:29 PM »
It is not unheard of for heat and A/C to share a circuit.  Often this is done using a properly rated 3-way switch.

I've seen some older Winnebagos where the A/C and the microwave are set up by the factory to share a circuit in this fashion.
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seilerbird

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Re: Electrical 101 - How do you run a new circuit?
« Reply #8 on: June 10, 2011, 02:25:11 PM »
Tom,

That's reasonable advice. I am a little apprehensive, though, given the many unusual experiences many have had with their technicians and their RV's. Should I be looking for some certification at one of the RV places, or is there an RV shop that specializes in electrical work, or ???

I suppose I need to start shopping that out. Being fulltime, I will really want to find someone who can accomodate us living in the rig and doing the work in a minimum amount of time. Does running that one circuit sound like a big deal?

Kim
I have no idea if there are certifications for RV techs or if there is a shop that specializes in electrical work. I would look for a Union Electrical contractor. Union electricians (like me) must serve a 4 or 5 year apprenticeship before becoming a journeyman. That includes 4 or 5 years of night school, usually at a college. Non-union electricians only have one real qualification, that they can breathe.

seilerbird

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Re: Electrical 101 - How do you run a new circuit?
« Reply #9 on: June 10, 2011, 02:27:41 PM »
It is not unheard of for heat and A/C to share a circuit.  Often this is done using a properly rated 3-way switch.
No, you would not use a three way switch. That is for turning a light (or some other load) off and on from two different locations.

What you would use is a single pole, double throw switch.

http://en.wikipedia.org/wiki/Switch

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Re: Electrical 101 - How do you run a new circuit?
« Reply #10 on: June 10, 2011, 02:53:52 PM »
Tom I am of small mind and there is much I do not understand, but least of all do I understand the difference between a 3-way switch and an SPDT switch.  Could you please explain this for me as I would like to learn.
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Re: Electrical 101 - How do you run a new circuit?
« Reply #11 on: June 10, 2011, 03:23:39 PM »
Tom I am of small mind and there is much I do not understand, but least of all do I understand the difference between a 3-way switch and an SPDT switch.  Could you please explain this for me as I would like to learn.

A three way switch controls a load from two different locations. I don't know why it is called a three way, there are two switches and four different positions. This page has a schematic diagram:

http://www.charlespetzold.com/blog/2007/09/151044.html

A SPDT switch means it only controls one circuit and there are two positions.

http://www.mobilecentre.co.uk/black-round-on-on-rocker-switch-spdt-20mm-hole-snap-in-p-514.html

Since the neutrals are all tied together you don't and never should switch the neutral. This would be the switch you would use to change between a 11o volt heater and cooler. One would always be hot and they would never be on at the same time. Some of these switches have a middle position where neither is connected, but that would not be necessary in this case.

SPST is your basic off on switch. One circuit one on position.

SPDT is your basic on position one, on position two switch for one circuit.

DPST is two circuits off and on.

DPDT is two circuits with two on positions.



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Re: Electrical 101 - How do you run a new circuit?
« Reply #12 on: June 10, 2011, 03:42:50 PM »
A three way switch controls a load from two different locations. I don't know why it is called a three way, there are two switches and four different positions.

A learned man once told me that three-way switches are so named because they have three terminals.  In similar fashion the rare and elusive four-way switch, I was told, has four terminals.  But the august sage who shared with me this arcane knowledge was non-union so perhaps he was not a worthy source.  He does breathe however.

I must admit that the difference between the 3-way switch and the SPDT switch yet evades my understanding.  Perhaps a few years of night school would provide me the background necessary to grasp concepts of such complexity and nuance.

I have heard tell that all Form C contacts are SPDT but not all SPDT contacts are Form C.  Another part of the mystery for us to ponder.
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skyking4ar2

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Re: Electrical 101 - How do you run a new circuit?
« Reply #13 on: June 10, 2011, 04:17:37 PM »

What you would use is a single pole, double throw switch.

http://en.wikipedia.org/wiki/Switch

Tom,

I appreciate the reference and that helps me absorb this switch concept better. So is there a junction box (?) somewhere where the circuit from the A/C joins the circuit from heater and the switch (convenient to the user) connects (?) them but keeps only one circuit hot? I can see this in my mind and I am sure there is a drawing with symbols that represents such.

(I am determined to understand this...the subject line says it all -  ;D)

Kim
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Re: Electrical 101 - How do you run a new circuit?
« Reply #14 on: June 10, 2011, 04:18:03 PM »
A "three way switch" circuit uses two SPDT switches to achieve the desired results, so in practice there is no difference in the hardware.

An SPDT switch is used when it is necessary to assure that two circuits are exclusive with each other.  That's a good idea if two devices share the same circuit, but probably unnecessary for a heater and na a/c unit if there are open slots for a breaker. If there are open slots for a breaker, I would simply install a separate breaker for each and let the main breaker deal with any possible overloads. If there is no breaker slot available, then I would go the route of the SPDT switch on a single hot wire from what is now the a/c breaker.  In either case, adding a breaker and wiring an additional outlet is not rocket science and you can do it with sufficient directions.

But I'm still in the dark about the OP's problem. If he is tripping the breaker on an inverter circuit, the solution is to plug the heater into a different circuit, one not served by the inverter and thus limited to 30A total.  But if there is no such outlet available, adding an outlet on an independent circuit is a viable solution.
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skyking4ar2

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Re: Electrical 101 - How do you run a new circuit?
« Reply #15 on: June 10, 2011, 04:52:04 PM »

But I'm still in the dark about the OP's problem. If he is tripping the breaker on an inverter circuit, the solution is to plug the heater into a different circuit, one not served by the inverter and thus limited to 30A total.  But if there is no such outlet available, adding an outlet on an independent circuit is a viable solution.

There is only one utility circuit available (see breaker panel) for all the receptacles. As you can see, that is one of the two breakers on the inverter (the one that keeps being thrown).
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seilerbird

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Re: Electrical 101 - How do you run a new circuit?
« Reply #16 on: June 10, 2011, 05:30:15 PM »

I must admit that the difference between the 3-way switch and the SPDT switch yet evades my understanding.  Perhaps a few years of night school would provide me the background necessary to grasp concepts of such complexity and nuance.

A three way uses two SPDT switches. It is used in a situation where you have light and a long hallway. You would turn on the light at the entrance to the hallway with one switch and turn the light off at the other end of the hallway with the other switch. An SPDT would be used if there was only one switch was required.

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Re: Electrical 101 - How do you run a new circuit?
« Reply #17 on: June 10, 2011, 05:49:17 PM »
There is only one utility circuit available (see breaker panel) for all the receptacles. As you can see, that is one of the two breakers on the inverter (the one that keeps being thrown).

The receptacle circuit is shown on line2, which does not indicate that it is on the inverter.  What am i missing?
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skyking4ar2

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Re: Electrical 101 - How do you run a new circuit?
« Reply #18 on: June 10, 2011, 06:07:36 PM »
The receptacle circuit is shown on line2, which does not indicate that it is on the inverter.  What am i missing?

Porky, I don't know - not sure how you determine that from the panel markings - the Xantrex Freedom 458 inverter has two breakers labeled AC OUT 1 (20 amp) and AC OUT 2 (15 amp) and the AC OUT 1 is the one that will trip - I cannot speak to how they are wired.
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Re: Electrical 101 - How do you run a new circuit?
« Reply #19 on: June 10, 2011, 06:35:14 PM »
Your inverter is probably wired like ours, with the 30A circuit feeding the inverter/charger and the 2 output circuits of the inverter feeding various outlets.  The inverter output doesn't go through the load center panel at all.  The breaker labeled "General Purpose Receptacles" feeds any outlets not on the inverter.  These are probably the water heater, engine block heater, refrigerator, and perhaps one or two other outlets inside.
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skyking4ar2

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Re: Electrical 101 - How do you run a new circuit?
« Reply #20 on: June 10, 2011, 07:04:29 PM »
Ned,

The more information I get, the more this is becoming clear to me. My wiring diagram PDF won't fit on the attachments, but I can now see that not all my power comes through the load center. I never could understand why the breakers were tripping on the inverter, and now I think I do...that's where this particular circuit is powered.

I think now I just need to chase the General Purpose circuit and see if it has a receptacle somewhere that I can utilize. If so, that solves the problem.
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Water Dog

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Re: Electrical 101 - How do you run a new circuit?
« Reply #21 on: June 10, 2011, 07:13:43 PM »
A three way switch controls a load from two different locations. I don't know why it is called a three way, there are two switches and four different positions. This page has a schematic diagram:

A three way switch has that name because of the three conductors, common, and two travelers; likewise a four way switch.
Dennis

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Re: Electrical 101 - How do you run a new circuit?
« Reply #22 on: June 10, 2011, 07:28:25 PM »
A three way switch has that name because of the three conductors, common, and two travelers; likewise a four way switch.

By that logic then a four way switch should be called a five way switch. Four travelers and a common. But then again you are forgetting the ground wire.

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Re: Electrical 101 - How do you run a new circuit?
« Reply #23 on: June 10, 2011, 07:36:35 PM »
Wow a lot of bandwidth in a short time.

To my point of view, it was far far easier, FOR ME, given the layout of my motor home, to simply run an additional circuit.   Though now that I think of it I likley could have done one of them off the A/C line, but I had the breaker already, so I just ran a new circuit.

Oh, the breakers are standard ones you can get at most places like Lowes, Home Depot, Joe's hardware, Sam'e electrical supply,,, Nothing exotic about them at all.                 
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Re: Electrical 101 - How do you run a new circuit?
« Reply #24 on: June 10, 2011, 07:40:04 PM »
By that logic then a four way switch should be called a five way switch. Four travelers and a common. But then again you are forgetting the ground wire.

No, the travelers sit in the passenger and dinette seats, and the common is in the drivers seat. The ground is the part you're driving on.  This is getting waaay too deep....! :D :D
Dennis

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Re: Electrical 101 - How do you run a new circuit?
« Reply #25 on: June 10, 2011, 08:14:44 PM »
As Ned describes, the power for the inverter comes through the 30A inverter feed breaker but never returns to the breaker panel. The breakers in the inverter handle the circuits powered that way. If you get the right loads on the AC1 Out and AC2 OUT circuits, you can trip the 30A breaker that feeds the inverter, but more often one of the branch breakers trips first.

I see there are no open slots on your breaker panel, so the best solution is the SPDT switch we discussed earlier, spliced to one of the a/c circuits. The output of the a/c breaker goes to the center (line) pole on the SPDT switch and the a/c wire to one of the two load terminals. The second load terminal would supply a new outlet to be used only for an electric heater. The neutral for the heater goes direct to the neutral bus in the breaker box. Likewise the outlet ground goes direct to the ground bus. Only the hot wire runs thru the SPDT switch.
Gary
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Re: Electrical 101 - How do you run a new circuit?
« Reply #26 on: June 10, 2011, 09:10:44 PM »
Kim,
If you can chase another 12ga romex cable from a location for the outlet (for your heater) to the breaker box then I would pull out the 20amp breaker on the side labeled "Line 1" and replace it with a double 20amp (available at Home Depot, just be sure its the same type). This exactly what I did to have a circuit for a space heater that wasn't on the inverter.

Ken

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skyking4ar2

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Re: Electrical 101 - How do you run a new circuit?
« Reply #27 on: June 11, 2011, 12:57:39 AM »
This exactly what I did to have a circuit for a space heater that wasn't on the inverter.

Ken,

That makes some sense; I really would not want a big amperage draw like the heater on the inverter anyway would I? Until this post, I never clearly realized where it was drawing the power from.

Kim
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Re: Electrical 101 - How do you run a new circuit?
« Reply #28 on: June 11, 2011, 09:04:22 AM »
You would want the heater on the inverter if you are going to use it without the generator running or being on shore power. The inverter gives you 110 volts from your battery (it inverts 12 volts to 110 volts). So if you are going to run it when you are on battery power only it will need to be on the inverter.

Gary RV Roamer

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Re: Electrical 101 - How do you run a new circuit?
« Reply #29 on: June 11, 2011, 09:42:38 AM »
If he tries to run an electric heater on the inverter, that 1500 watt power draw is going to eat his two house batteries in under a minute. But if its tv or a toaster, maybe the inverter circuit is a wise choice. However, the tv shouldn't be popping a breaker - we are talking maybe 100 watts.

The OP needs to think about what he wishes to power and under what circumstances. Adding circuit to the inverter doesn't achieve a lot, since it has a 30A max combined throughput anyway.
Gary
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