Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
Old 01-09-2020, 08:52 PM   #1
Senior Member
 
Join Date: Aug 2019
Location: Central NJ
Posts: 1,001
Tapping a 120V circuit from a 240V circuit

Hi. I apologize, this is not an RV related question. I know there are some very knowledgeable people here and I've long since forgotten my password(s) to the home improvement sites. I accept that this post may be deleted as being improper. Thanks if it remains.

My neighbor is having a water softener, filter, etc.... installed and ask me to help him get a new outlet installed. His well pump is in a separate little room in his basement and he said there is a switch there for the pump that would be convenient to tap off of since the new equipment would also go in this room. I have not seen his setup yet, but if it is like mine then his well most likely runs off a 240V/20A feed.

Ok, so what I what to know is if its "OK" to tap a 120V circuit off an existing 240V feed? Personally I don't see a safety problem with this. The breaker with protect the line. None of the wires can ever draw more than the 20A of the breaker. There should be no problem with the "unbalanced" load on the neutral. I doubt the well pump actually draws anywhere near the 20A of the circuit. A quick search shows that a 1HP well pump is ~9A or less than 50%.

If its not OK, why and what options are there? Running a new line is unlikely as I believe his panel is full. We could could put a small sub panel in the well room and then run a circuit to the well and the new outlet, but this seems like over kill. We could try to tap some other nearby circuit (basement lights, etc..) but I see the advantage in keeping all the water/well related circuits on one branch.

Thanks again.
Jim M.
__________________
2020 Flagstaff Super Lite 26RBWS
Former: 2017 Rockwood MiniLite 2104S
2015 Silverado 2500HD 6.0L Gas
jimmarako is offline   Reply With Quote
Old 01-09-2020, 09:11 PM   #2
Senior Member
 
Join Date: Apr 2016
Location: Cedar Creek Lake, TX
Posts: 3,477
Do you even have a neutral (white wire) on the pump circuit? It isn't required for 240 volts so it often isn't run with the circuit unless something is 120 volt.
__________________
Cedar Creek Lake, Texas
2019 Keystone Loredo 290SRL
2019 Ram 2500 4x4 Cummins crew cab
Andersen hitch
CedarCreekWoody is offline   Reply With Quote
Old 01-09-2020, 10:01 PM   #3
Senior Member
 
Kirk S's Avatar
 
Join Date: Jan 2017
Location: Savannah
Posts: 791
If I was doing it and had a fourth wire in the existing run I would cut the 240 volt 20 amp feed to the pump and insert a small sub panel, reconnect the pump to a 20 amp breaker in the subpanel and add another breaker for the receptacle.
I'm not sure how you would add a 120 volt circuit without a neutral. You could get 120 volts between a hot leg and ground but that's not safe.
__________________
Kirk
2017 Forester 3051S
Kirk S is offline   Reply With Quote
Old 01-09-2020, 10:05 PM   #4
Senior Member
 
Join Date: Aug 2019
Location: Central NJ
Posts: 1,001
Quote:
Do you even have a neutral (white wire) on the pump circuit? It isn't required for 240 volts so it often isn't run with the circuit unless something is 120 volt.
Good question, I didn't think of that. When I re-wired my house I ran a neutral with all 240V circuits. I figured its already required for dryers and stoves that its only a matter of time before they all require it. Get ahead of the curve.

I asked my neighbor to check. If there is no neutral then Plan A falls apart. I'll expand the question a bit. If the breaker has the proper spaces for two wires could I run a new line from one side of the breaker?

Thanks
Jim M.
__________________
2020 Flagstaff Super Lite 26RBWS
Former: 2017 Rockwood MiniLite 2104S
2015 Silverado 2500HD 6.0L Gas
jimmarako is offline   Reply With Quote
Old 01-09-2020, 10:07 PM   #5
Senior Member
 
Join Date: Aug 2019
Location: Central NJ
Posts: 1,001
Quote:
Originally Posted by Kirk S View Post
If I was doing it I would cut the 240 volt 20 amp feed to the pump and insert a small sub panel, reconnect the pump to a 20 amp breaker in the subpanel and add another breaker for the receptacle.
I thought of this. Thats a lot of work, and cost for a single outlet. If everything else falls apart I'll probably suggest just taping something else.

Jim M.
__________________
2020 Flagstaff Super Lite 26RBWS
Former: 2017 Rockwood MiniLite 2104S
2015 Silverado 2500HD 6.0L Gas
jimmarako is offline   Reply With Quote
Old 01-09-2020, 10:27 PM   #6
Senior Member
 
Kirk S's Avatar
 
Join Date: Jan 2017
Location: Savannah
Posts: 791
When I had to add a 120 volt circuit to a full panel I was able to replace one full size single pole breaker with two half size breakers in the same space. I reconnected the original circuit to one and ran the new circuit from the other.
I was fortunate that the brand panel I was working with supported that type breaker.
I have done it with GE and Cutler-Hammer.
__________________
Kirk
2017 Forester 3051S
Kirk S is offline   Reply With Quote
Old 01-09-2020, 10:37 PM   #7
Member
 
Join Date: Aug 2018
Posts: 56
Depends on the type breaker if it’s a 20 amp breaker per leg and you put an extra wire in one leg going to the plug and have a neutral bus to put your neutral leg to ,it will work as long as you do exceed 20 amps per leg . It’s probably a code violation in most places but it will work and is safe as the breaker will trip with a fault or over load on one leg or both it’s 20 amps per leg it just trips both sides no matter which leg has the fault on it to keep a 240 volt device from only getting 120volts and damaging the device . The only difference in a 240 breaker and 2 , 120 breakers on different busses in the box is a fault on 1 leg will trip both sides of a 240 breaker to protect the device and to prevent someone from coming along to work on it thinking it’s off but really only 1/2 power. I have a plug wired into one side of a 240v 20amp breaker in my power panel on the outside of my house to plug my truck up it the winter. Only difference is the other side is vacant it went to a hot tub we no longer have and I didn’t want to buy a breaker just for one plug that gets used very little.
Sfgoble is offline   Reply With Quote
Old 01-09-2020, 10:41 PM   #8
Senior Member
 
TimVWulp's Avatar
 
Join Date: Jan 2015
Location: West Michigan
Posts: 641
Is the power cable to the well a four wire cable???? if it is it should have a black wire red wire a white wire and a green wire Yes it can be done if all parts are rated for 20 amps.

Black and Red wires are 220 volts 110 volts each to the common wire.
White wire is common or neutral wire for 110 volts back to the neutral bar in the breaker panel.
Bare or Green wire is the ground wire and is to be used as a safety wire back to the ground bar in the breaker panel only!!!!!!!!

If the power cable to the well is only a three wire cable the answer No.

It is very dangerous and illegal to use the ground (bare or green wire) wire in a 3 wire cable as a common or neutral wire. If you do this and some is electrocuted I smell a law suit.

Be very careful with this Tim
TimVWulp is offline   Reply With Quote
Old 01-09-2020, 10:48 PM   #9
Senior Member
 
Join Date: Aug 2019
Location: Central NJ
Posts: 1,001
Quote:
Originally Posted by TimVWulp View Post
If the power cable to the well is only a three wire cable the answer No.

It is very dangerous and illegal to use the ground (bare or green wire) wire in a 3 wire cable as a common or neutral wire. If you do this and some is electrocuted I smell a law suit.

Be very careful with this Tim
Thanks to all for the suggestions so far. Just to clarify, I would never use the ground as a make shift neutral. I realize the danger of such. I'm hoping there is the neutral wire but I'm betting against it.

Jim M.
__________________
2020 Flagstaff Super Lite 26RBWS
Former: 2017 Rockwood MiniLite 2104S
2015 Silverado 2500HD 6.0L Gas
jimmarako is offline   Reply With Quote
Old 01-09-2020, 11:04 PM   #10
2012 Solera
 
Join Date: May 2012
Posts: 1,822
A transformer?
https://www.homedepot.com/p/Power-Br...000W/302542246
__________________
JLeising
2012 Solera "S"
Calif SF Bay Area
JLeising is online now   Reply With Quote
Old 01-09-2020, 11:38 PM   #11
Senior Member
 
Join Date: Sep 2019
Posts: 459
For safety's sake you shouldn't use one leg of a bridged breaker. Install 2 single 20A breakers in it's place, and of course, you'll only use one.

Marking tape is perfectly acceptable as long as local regs allow it.
Just wrap all exposed wire with white marking tape on each end, and connect it to the neutral buss.
https://www.amazon.com/SAISN-Electri...8630952&sr=8-2 I'm assuming the existing run includes a ground wire.
n1acguy is offline   Reply With Quote
Old 01-10-2020, 12:22 AM   #12
Coach
 
Join Date: Dec 2016
Location: Western PA
Posts: 667
I would advise against tapping one leg of the 240v. I also wouldn't recommend the subpanel off pump wiring as you'd likely only be feeding it with #12 wire unless you would make a new run. The duplex breaker in the main box is probably the best idea. If you want to do the subpanel, I would recommend changing the 20a 240 in the main panel for a 50a and install a 50a subpanel with #8 wire providing his electric service can handle that.
__________________
Cut it 3 times and it's still too short...

2017 Sandpiper 381RBOK
2006 Ram 3500 Cummins Dually
valleyduo is offline   Reply With Quote
Old 01-10-2020, 03:00 AM   #13
Senior Member
 
Join Date: Apr 2016
Location: Port Charlotte Fl/Hinsdale Ma
Posts: 4,823
You guys are killing me. You cannot use a 20 amp 3 wire 240 volt circuit to get 120 volts circuit. It is very possible that the existing pump might just be 120. Problem solved. Did anybody think about ordering a 240 volt water softener if need be? Some softener systems don't even use electricity.

What's the odds that this separate little room has a light in it? Softeners draw very little amperage. Mine has a wall wart transformer. Add an outlet to the lighting circuit.
cavie is offline   Reply With Quote
Old 01-10-2020, 02:45 PM   #14
Member
 
Join Date: Apr 2017
Location: Muncy Valley PA
Posts: 96
Don't. First off it is not code. If something would happen and there is a fire the insurance company won't pay. Do not ever count on a breaker tripping to save wires from melting and burning down your home. That's why you have smoke detectors to get you out.
Tom911 is offline   Reply With Quote
Old 01-10-2020, 02:49 PM   #15
Member
 
Join Date: Feb 2017
Posts: 73
Once upon a time, a lot of houses had a wire running from the fused panel to the receptacles and a bare wire running from the recept to earth ground under the house to complete the circuit. Functionally this worked, but, not safely. Then "neutral" (common, white) wires were incorporated with the power wire (romex, etc.), much safer and easier, then 60 odd years later, the ground (grounding, bare wire was added). You sound like a thoughtful guy who covers the angles. I believe you can figure out what will work best for your situation
tonys is offline   Reply With Quote
Old 01-10-2020, 02:52 PM   #16
Senior Member
 
DouglasReid's Avatar
 
Join Date: Jun 2016
Location: Maurice, LA
Posts: 4,095
Quote:
Originally Posted by jimmarako View Post
I thought of this. Thats a lot of work, and cost for a single outlet. If everything else falls apart I'll probably suggest just taping something else.

Jim M.
It is not much and probably the safest way to go, you can cut off whichever whenever you need to.

Electrical services are nothing to cut corners on..........Fires result as do deaths as a result of "Jury Rigging"
__________________
2012 Wildcat Sterling 32RL, Gladiator Qr35 ST235/85R16 Load rating G, TST 507 TPMS w/ Flow-thru Sensors & Repeater, Reese Sidewinder 16K Pin Box, PI EMS HW50C
2009 Chevy Silverado 2500HD CCSB LTZ Diesel, Fumoto Oil Drain Valve, Turbo Brake activated, 39 gal Aux Tank W/ Fuel Pump transfer, Air Lift Loadlifter 5000 air bags.
DouglasReid is offline   Reply With Quote
Old 01-10-2020, 03:35 PM   #17
Senior Member
 
Join Date: Oct 2015
Location: Wisconsin/Florida
Posts: 1,905
I see you have mentioned wiring to a new outlet in the basement. No matter how you get the supply, "basement" and "well room"=wet area and you should be using a GFI outlet.
PenJoe is offline   Reply With Quote
Old 01-11-2020, 08:01 PM   #18
Member
 
Join Date: Jul 2015
Location: Western PA
Posts: 88
Stay away from touching 220 circuits when using the current on a water system. I never trust one breaker to trip a second one. Just not enough internal energy to do the job (FAST). Here are easy, safe and code approved ways. Buy a Mini Breaker set. Two circuits from one panel lug. Square D, GE, and Murry sell them. Number two and the safest method when faced with space issues as you describe is to find a circuit with little load in the house. Many circuits in homes have these installed. Add a GFIC-Arc Fault Receptacle outside the breaker box and send a new wire to the unit you're trying to power along with the original supply line. Anytime water is involved, along with electricity, you NEED protection. It's CODE. Everything down steam of the GFIC will also be protected. I have no problem with a double lug as far as safety is concerned but inspectors cannot approve them if a sale is involved. Good luck but also get proper help with your project.
weatherguru1 is offline   Reply With Quote
Old 01-11-2020, 08:06 PM   #19
Senior Member
 
Join Date: Jan 2015
Location: Englewood FL
Posts: 2,797
Quote:
Originally Posted by weatherguru1 View Post
...I have no problem with a double lug as far as safety is concerned but inspectors cannot approve them if a sale is involved. Good luck but also get proper help with your project.
Are you saying that a double tapped breaker is against code. A number of breakers (like Square D QO) are designed to be double tapped and, unless it is a recent change, why put a feature in a spec sheet that is counter to the NEC.
__________________

2015 335DS
ScottBrownstein is offline   Reply With Quote
Old 01-11-2020, 08:48 PM   #20
Member
 
Join Date: Jul 2015
Location: Western PA
Posts: 88
Scott, In our area, Western PA, inspectors will not allow double lugs. You can use double breakers, I.E.Mini breakers, as I said. My inspector works specifically for Atlantic Inland.

The NEC is there for a reason, Safety. Why it is not he same across the land is anyone's guess. For example, and there are many, NY State allows and demands Breaker Boxes be grounded to Natural Gas Lines. Try that in PA and there goes your License and or credibility. Go Figure.
weatherguru1 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.



All times are GMT -5. The time now is 11:34 PM.