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post #1 of 27 Old 07-13-2020, 10:53 AM Thread Starter
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Electrical questions

So, I really need more outlets instead of running extensions from hell and half of Georgia and back as I really don't want the joint to burn down.
I have a 30 amp circuit that I ran awhile back for an RV we no longer have. In the circuit box it's a twin breaker switch for 30 amps. Can I just replace it with 2 15 amp circuit breakers and rewire accordingly? Or.with beefed up wiring could I go to 20 amp breakers?

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post #2 of 27 Old 07-13-2020, 11:07 AM
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You can replace it with two 20's. The wire should be rated much higher than that. So you're fine.
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post #3 of 27 Old 07-13-2020, 11:13 AM
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When you say it’s a double breaker, it sounds like it’s a 220v circuit.

Two 15a breakers will result in 2 separate 110v circuits. What’s most important is that the breaker be properly sized for the downstream wiring and devices.


What do you want to plug in to the new outlets you plan?
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post #4 of 27 Old 07-13-2020, 11:56 AM Thread Starter
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There's actually 2 30 amp circuit breakers.

The one on top is connected to a no longer functioning lawn watering pump outside by the lake so it's open and the other under it is the same that fired up things for the RV. I'd be ok with making two separate 20 amp breakers or maybe even 4, but that's overkill. It's still good to know i have the option to expand if I ever find the need .
So anyway..I can take 1 of the 30 amp breakers, put in 2 20 amps in its place and run heavier wiring for them? The RV line only runs about 7 feet to the outside of the garage door. I have no use for it anymore.

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post #5 of 27 Old 07-13-2020, 12:31 PM
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You must make sure that you don't have a 240 volt branch circuit there. If the pump was 120 volt and the RV was 120 volt (most 30 amp RV circuits are 120 volt), then you can change the two thirty amp breakers with 20's. Here's the caveat:

If each one of those circuits does not have it's own neutral, you must tie the breakers together, as you will be sharing a neutral between the two legs. This is so if one circuit trips the fault will kill the other circuit on the same neutral.

Easiest is to pull the cover off and identify the presence of none, one, or two neutrals for the two breakers. Two neutrals-two single breakers. One neutral, tied breakers. No neutral, well...
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post #6 of 27 Old 07-13-2020, 12:38 PM
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Yeah, go for it, but a few comments. First, your 30 amp circuits should have 10 gauge conductors, so replacing with 20 amp breakers, you can go with 12 gauge (so lighter, not heavier, wire is okay). That pump breaker with the copper wire gang is worrisome to me. 240 volt circuits are normally ganged together (like your RV breakers) so that both hot wires are shut off together. I'd recommend replacing the pump breakers with your RV ones, or get a handle tie (the clip that connects the two breaker toggles) to replace that iffy copper wire. Good luck- I envy your having so many spare breaker slots. BTW, I'm not an electrician, so my comments are worth what you paid for them!
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post #7 of 27 Old 07-13-2020, 01:37 PM Thread Starter
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I'm definitely not an electrician either, but can't afford to pay one so I have to make sure I'm doing this correctly. It might have to wait a while because right now the garage is ungodly hot right now..or perhaps I just ate lunch and it feels a lot hotter than it was just a half hour ago. Lol
I think that's the ticket. I had a big sandwich and fries and I'm not a big eater. In fact it feels like nap time so I do believe that since I don't have to be anywhere any time soon I'll do just that . But wait! I just got a call from "Publishers Clearing House" informing me I just won 5 MILLION BUCKS! The only problem is I didn't enter anything and don't quite trust whoever it was that called. G'night folks.

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post #8 of 27 Old 07-13-2020, 06:54 PM
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As long as the wiring is properly sized for the breaker, it doesnt matter what voltage you put through it (for residential voltages anyways. Dont put 5kV through 14 gauge romex). That said, make sure you have all the wires youd need to be running 2 120v circuits. Looks like youve got a 220v circuit there now, so 2 hots and a ground. You need a neutral for 120v, so youd be able to get 1 complete circuit with the wires being what i guessed. You could do something incredibly stupid using the ground wire as a neutral and tying the neutrals for both circuits together, but theres a reason i described that as incredibly stupid

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post #9 of 27 Old 07-13-2020, 08:38 PM
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Your gonna have to run a neutral for 120v. For a 20 amp circuit, thats a minimum of 12 gauge, if its more then 100 ft from the breaker, Id go up to 10 gauge. The wire thats there for the 220 circuit can be reused, but you need to run the neutral, and ideally a ground wire if not already present.

Most areas have NM cable (multiple wires that is ganged up in a single sheathing), if thats the case, you will need to run 2 sets of 12 gauge cable (romex, nomex, etc)

If your lucky enough to have conduit, you can just run the one neutral wire that can serve both 20 amp circuits (networked neutral), so long as the breakers are side by side (top to bottom) if they are not, then a dedicated neutral would be required for each breaker

You also need to be certain that ALL switches and outlets are also rated to 20 amps.

When in doubt about what your doing, stop. And seek information, ideally from someone that knows electric that can be on site.

If the breakers dont come out easy, do not pry with a metal screwdriver.

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post #10 of 27 Old 07-14-2020, 01:37 AM
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Let me try to explain 230 volt service.

Think of a flashlight with two batteries. (Don't go LED on me here.)
On each battery there is a flat end and bump end. When the batteries are installed, bump to flat, the voltage measured across the two batteries is 3 volts. If the batteries are installed bump to bump or flat to flat the voltage measured across both is 3 volts.

You're going crazy and don't understand how that is possible. It is simple, voltage is measured in reference to another point. With the batteries installed bump to bump or flat to flat, the measurement is from -1.5 volts to +1.5 volts or 3 volts total between the measuring points. North American domestic AC current is supplied this way. We connect Neutral to the center (bump to bump) and use the Neutral for all of our normal 115 volt appliances. Half of our 115 volt is positive and the other half is negative. For that 230 volt table saw, we connect across the positive and negative parts of the distribution.

The way that our circuit breaker boxes and circuit breakers are designed utilize being able to grab the positive or negative for 115 volts and grab both for 230 volts.

From your picture, my guess is that you have two 115 volt that are ganged together. Regardless of use, it is not a good way to do things. You probably replace both of those circuit breakers and have two 115 volt circuits and a single 230 volt circuit. Just be sure to buy the breakers that are the same brand as those you are replacing.

By the way, Neutral (White wire) is tied to the green wire (Ground) at one place and only one place in the house, inside the main circuit breaker box. Is your cable TV pixelating? You probably have two connections between Neutral and ground. Look in the sub panels and remove the green to white jumper to solve the problem. No, it is not a code violation to do so.

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post #11 of 27 Old 07-14-2020, 02:11 AM
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Quote:
Originally Posted by NoThankyou View Post
If the batteries are installed bump to bump or flat to flat the voltage measured across both is 3 volts.

You're going crazy and don't understand how that is possible. It is simple, voltage is measured in reference to another point. With the batteries installed bump to bump or flat to flat, the measurement is from -1.5 volts to +1.5 volts or 3 volts total between the measuring points.
NO!
That is not how the U.S. system works (nor batteries), and you made an egregious math error with a missing minus sign.

With batteries positive-to-positive or negative-to-negative, your total voltage across the pair is zero volts. Mathematically, this is 1.5 + (-1.5) = 0

I wasn't going to mention it, but the original poster already thinks that there are 15 amps on each wire of a 30 amp circuit. That is the same type of error as your explanation. The same amperage flows through the entire circuit...30 amps.
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post #12 of 27 Old 07-14-2020, 07:07 AM
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assuming you are talking about the two 30a single pole circuit breakers, tied toogether with a piece of copper wire.

you can pull the copper tie bar, and have two independant 30 amp circuits (not used for typical residential receptacles). they should be used for 30 amp loads with the proper sized wire (min 10 ga)

or you can remove one or both 30 cb's and replace it with a 20 amp cb, then use it as a typical 120vac branch circuit (using 12ga wire) - with a neutral and a ground - supplying to lights and or receptacles.

i would recommend that your seek the help of someone knowledgeable about electricity when you do the work. it is fine to ask questions here, but it is much better to have someone there seeing what you see when the work is being done. jmho

Last edited by TimPa; 07-14-2020 at 10:05 AM.
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post #13 of 27 Old 07-14-2020, 09:40 AM Thread Starter
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Yeah..I think I'm going to have to find an electrician to at minimum guide me right so I don't screw this up. I've come close enough to a fire long enough and certainly don't want to add to the risk. It's not that I don't know how to run a simple line, but running from the source and screwing it up can be catastrophic and the last thing I need is a fire and the insurance company to blame the whole thing on me. I do have a friend with some electrical background although his primary skills were that as a jouneyman plumber. I'll have to have a talk with him and see what he knows about the subject. Sometimes we have to kind of "flesh out" whether they know what they say they know and whether they're just blowing smoke, but I do know he's well acquainted with several other older tradesmen in the area.

I figured it's time to change my signature so hold your breath. This is it.
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post #14 of 27 Old 07-14-2020, 10:43 AM
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Quote:
Originally Posted by NoThankyou View Post
Let me try to explain 230 volt service.

Think of a flashlight with two batteries. (Don't go LED on me here.)
On each battery there is a flat end and bump end. When the batteries are installed, bump to flat, the voltage measured across the two batteries is 3 volts. If the batteries are installed bump to bump or flat to flat the voltage measured across both is 3 volts.

You're going crazy and don't understand how that is possible. It is simple, voltage is measured in reference to another point. With the batteries installed bump to bump or flat to flat, the measurement is from -1.5 volts to +1.5 volts or 3 volts total between the measuring points. North American domestic AC current is supplied this way. We connect Neutral to the center (bump to bump) and use the Neutral for all of our normal 115 volt appliances. Half of our 115 volt is positive and the other half is negative. For that 230 volt table saw, we connect across the positive and negative parts of the distribution.

[...]
You're right. I am going crazy. I saw your post and was confused. I got out the following:

Equipment:
* 2 new C batteries
* Fluke model 112 "True RMS Multimeter" set to measure DC volts.

Measurements:
* The batteries each measured 1.6 volts.
* With the probes reversed, each battery measured -1.6 volts.

* The two batteries arranged bump to flat measured 3.2 volts.
* With the probes reversed they measured -3.2 volts.

* The two batteries arranged flat to flat measured 0 volts
* With the probes reversed, they measured -0 volts

* The two batteries arranged bump to bump measured -0 volts
* With the probes reversed, they measured 0 volts

Note: The measurements were rounded to the nearest 0.1 volt.

The measurements match what I was taught in high school physics, as well as what I expected.

This has nothing to do with AC circuits nor how a 230 volt AC circuit can be divided into two 115 volt AC circuits.
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post #15 of 27 Old 07-14-2020, 12:01 PM
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Originally Posted by furnacefighter15 View Post
Your gonna have to run a neutral for 120v. For a 20 amp circuit, thats a minimum of 12 gauge, if its more then 100 ft from the breaker, Id go up to 10 gauge. The wire thats there for the 220 circuit can be reused, but you need to run the neutral, and ideally a ground wire if not already present.

You are going to have to HAVE a neutral for 120 volts. From my reading you aren't sure if you have a single 240 volt circuit or two 120 volt circuits tied together. The only way to know what you really have is to peek behind the panel cover and see how many conductors you have to the two existing breakers and the neutral bar. Seeing as how the handle tie is homemade, you could easily already have two 120 volt circuits that are sharing a neutral but going two different places. Regardless, if you have three insulated current carrying conductors of at least #12 AWG (usually black, red, white) and a separate ground, you can legally split it into two separate circuits. Just change the breakers to 20 amp, which is standard for receptacles, and put the handle tie back in the new breakers

Most areas have NM cable (multiple wires that is ganged up in a single sheathing), if thats the case, you will need to run 2 sets of 12 gauge cable (romex, nomex, etc)

If your lucky enough to have conduit, you can just run the one neutral wire that can serve both 20 amp circuits (networked neutral), so long as the breakers are side by side (top to bottom) if they are not, then a dedicated neutral would be required for each breaker Again, they must have a handle tie if sharing a neutral.

You also need to be certain that ALL switches and outlets are also rated to 20 amps.

Receptacles and switches in the United States are not required to be 20 amp rated on a 20 amp circuit. The NEC allows for 15 amp rated switches and receptacles on 20 amp circuits. If you have equipment that requires over 15 amps, it will have a different type of cord plug, with one blade turned 90 degrees to the other (most folks have never seen one). That is why 20 amp receptacles have a slot on the side of one of the blade slots. Regular 15 amp duplex receptacles are fine, but please stay away from the 99 cent jobs. Even though technically UL listed, they are pretty flimsy.
When in doubt about what your doing, stop. And seek information, ideally from someone that knows electric that can be on site.

If the breakers dont come out easy, do not pry with a metal screwdriver.

Agreed. Your picture is of a Square D HOM panel. HOM uses breakers called "stab in". They snap onto a rail on the outside and then stab onto the busswork in the panel. So, pull out to the left from the center of the body and keep pivoting to the left until it pops off of the rail. Installation is just the opposite. Snap the back to the rail and pivot right until it stabs onto the buss. Should be easily done.

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What you propose to do does not have to be hard, nor does it need to be too confusing. I’ve been making a living doing this for 40+ years. You have a good starting place with at the very least two insulated wires, one on each breaker. That alone would make one complete 120 volt circuit. If it is a black and white (which it probably will be if it is Romex), move the white to the neutral bar, swap the circuit breaker, and install receptacles on the other end.

However, you may have enough conductors to make both circuits (as explained above, you need at least three insulated + ground). Pull the panel cover off and look before you pay someone to look for you. And as several have said, if it becomes confusing, go for the pro.

Another $000,000,000.02 worth of advice,
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post #16 of 27 Old 07-14-2020, 12:28 PM
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you don't say where the breakers are in relation to the new outlets you want or what wire there is. 10-2 or 10-3?

if the panel is in your shop this is real easy to rewire a couple of branch circuits. you could do up to four 20 amp branch circuits off those two 30 amp breakers using double breakers and replace all the #10 wire with #12 wire for each circuit.

if the panel is not in your shop but the rv outlet is, you can still wire in a single branch circuit off the rv plug. now assuming you have 10-2 romex... just replace a single 30 amp breaker with a 20 amp breaker. the other breaker is abandoned in place. hook the black wire to the new 20 amp breaker and the white wire to the neutral buss for a 120 volt branch circuit. replace the outlet with a 20a receptacle. you can also wire a bunch more outlets to this new circuit. the method would depend on what wall type you have, ie: studs, sheetrock or block.

if you have 10-3 romex the whole plan changes.
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post #17 of 27 Old 07-14-2020, 12:36 PM
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prior to the 1996 nec code, you could have put a sub panel on 10-2 wire. my barn panel is this way. i run my whole shop on a 30a, 240v, 2 wire w/ground 10 space sub panel 200 feet away. serious voltage drop if you were to run any 30a, 240v equipment, not so bad with my 20a, 240v compressor
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post #18 of 27 Old 07-14-2020, 12:51 PM
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Originally Posted by _Ogre View Post
prior to the 1996 nec code, you could have put a sub panel on 10-2 wire. my barn panel is this way. i run my whole shop on a 30a, 240v, 2 wire w/ground 10 space sub panel 200 feet away. serious voltage drop if you were to run any 30a, 240v equipment, not so bad with my 20a, 240v compressor
Even though it's not germane to this discussion, what you are describing is not correct. Prior to 1996 (or maybe it was a later code cycle), you were permitted to run feeders without a separate ground to an outbuilding, as long as no other ground path existed. In other words, you were permitted to treat the outbuilding as a separately derived system (i.e. not a subpanel), as long as a few conditions were met.

What you described above was implying that you used the ground wire as a (current carrying) neutral, and this has never been permitted.
.
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post #19 of 27 Old 07-16-2020, 08:11 PM
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never mind. Just realized it's an old post. Comment is mute at this point.

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post #20 of 27 Old 07-17-2020, 06:33 PM
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With batteries positive-to-positive or negative-to-negative, your total voltage across the pair is zero volts. Mathematically, this is 1.5 + (-1.5) = 0
Rick,
In math you are correct, sort of. However with voltage it is just a little bit different. Voltage is measured from a reference point. Normally we consider the reference point as zero or ground. In my example the reference point is 1.5 volts BELOW ground or -1.5 volts. If you measure from -1.5 bolts to +1.5 volts you get three volts.

Just as with common household AC, there is a negative phase and a positive phase. From the positive phase to the negative phase is 230 volts. From either phase to neutral is 115 volts.

It is all in the reference point.

Rich
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