NEMA L14-20 Outlet Wiring Question

Reply

  #1  
Old 01-24-16, 12:25 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
NEMA L14-20 Outlet Wiring Question

I have a 30A circuit powering a wall heater in my garage. I never use the wall heater, so I wanted to convert it into a 240V outlet to charge my Chevy Volt. The problem is it's only 3 wire, not 4, so I'm curious how to properly wire the NEMA L14-20 outlet (which is 4 wire compatible, 2 hots, ground and neutral) without having to run 4 wire all the way back to my breaker box.

This is the outlet I have: Robot Check

The next question I have is can I plug a normal NEMA L14-20 plug into that outlet if it only has the 3 wires I mentioned? Like this http://www.amazon.com/gp/product/B00002NAT4
 
Sponsored Links
  #2  
Old 01-24-16, 12:28 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,150
Received 1,113 Votes on 1,033 Posts
You can't wire a four prong receptacle to a two wire circuit with ground properly.

With a four wire receptacle the neutral and the ground must be kept separated. That means you need a three wire cable w.ground.

The plug you linked to will fit the receptacle you linked to but the four wires are still needed.
Your charger requires neutral and you need the ground for protection.
 
  #3  
Old 01-24-16, 12:40 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
So essentially I cannot use the 2 wire line I have already run from the breaker box to the location in the garage? I have to run a new 3 wire line from the breaker box?

There's no getting around that and making a 2 wire line work? Are there any 240V outlets and plugs that I could use to charge my car through my EVSE?
 
  #4  
Old 01-24-16, 12:42 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,150
Received 1,113 Votes on 1,033 Posts
If your charger specifies that type of connector and also requires 120/240v then you must run four wires.
 
  #5  
Old 01-24-16, 01:26 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
Can you help me understand why? If it's just a neutral wire, what happens if you run something off of the plug without it?

Is there a 240 outlet out there that would be compatible with the 2 wire circuit I have already run? I really want to avoid having to cut open the drywall next to the breaker box and then run 3 wire all the way out to my garage.
 
  #6  
Old 01-24-16, 01:42 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,150
Received 1,113 Votes on 1,033 Posts
Technically the ground wire and the neutral wire connect in the same place at the panel.
The neutral is used as a current carrying wire and the ground is not. The ground is only there as a safety.

If you use the ground wire you currently have as a combination neutral and ground wire AND it opens...... you will have 120v on your charger case and most likely on the car too.

This two wire with ground system has been used for years on appliances but now appliances are requiring a neutral. I've seen many people shocked and not understanding why when they lose the one wire that doubles as a ground and neutral.
 
  #7  
Old 01-24-16, 01:48 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,583
Received 13 Votes on 11 Posts
If it is 120/240 the device requires both 120 volts and 240 volts to work. Best example is most electric dryers. The heat on them is 240 volts but the motor and controls are 120 volts so you need a neutral.

Your house is supplied with 240 volts. The 120 you use is derived from one leg (either leg) of the 240 and the neutral which is a center tap on the secondary of transformer that supplies your house.

Name:  TransformerB-withground.png
Views: 2894
Size:  19.7 KB
 

Last edited by ray2047; 01-24-16 at 04:19 PM.
  #8  
Old 01-24-16, 04:07 PM
Handyone's Avatar
Member
Join Date: Aug 2000
Location: U.S.
Posts: 5,450
Received 0 Votes on 0 Posts
The manufacturers make it pretty clear on requirements for home charging.
4-wire 240v is the fastest charge, (4-wire required for safety and proper operation).

Have you contacted the utility company to see if they offer any incentives or rebates?
 
  #9  
Old 01-24-16, 04:38 PM
L
Member
Join Date: Nov 2015
Posts: 1,469
Received 70 Votes on 64 Posts
FYI. You wall heater probably did not even use Neutral as most don't.
Neutral is only needed if your appliance or equipment uses 120V. Most heaters only use 240V, thus no need for neutral.
White wire from existing cable probably is used as hot not neutral. It is supposed to be marked, but many don't.

If your charger only requires 240V, you can use existing 3 wires (including ground). But if NEMA L14-20 is required, it probably requires 120V as well.
 
  #10  
Old 01-24-16, 10:01 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
The NEMA L14-20 is not required, it was just what was suggested by a fellow Volt owner who has this charger setup. The charger will only be used at 240V on this plug.

Long story short, I modified the factory charger which originally was a 120V plug/charger. After the modifications to the charger it is now a 240V charger with 4 wires (2 hot, neutral, ground). I made an adapter with a NEMA 14-20 recepticle to the original 120V plug, so I can just plug the charger into a normal 120V outlet if I need to.

It sounds like I definitely need the neutral from the circuit breaker since the plug into the charger has one. No way around it given the above described facts?
 
  #11  
Old 01-24-16, 10:33 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,583
Received 13 Votes on 11 Posts
After the modifications to the charger it is now a 240V charger with 4 wires (2 hot, neutral, ground).
No it is not 240. Two hots, neutral, ground is 120/240.
I modified the factory charger which originally was a 120V
You probably modified the charger output but the controls are still 120 volts.
No way around it given the above described facts?
Yes, no alternative. You must have a neutral to provide 120 volts for those components that are 120 volt.

Side note: Remember my example with the dryer above? Both gas and electric dryer are the same. They are 120 volt except for the heat source. In one they put in a gas burner. In the other they put a 240 volt heat source but you still need 120 volts to run the dryer. Your charger is probably the same situation.
 
  #12  
Old 01-25-16, 09:08 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
What if I'm only running 240 off the outlet?
 
  #13  
Old 01-25-16, 09:54 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 35 Votes on 27 Posts
Rather than argue why don't you just do as you propose, test it out, and then tell us it works just fine...or destroyed the charger.

Technically it would be a code violation since an L14-20 is a 250/125 volt receptacle. Someone could easily think that they could get a multi-wire branch circuit (two separate 120 volt circuits) from that using a four-conductor cord. That would be a significant hazard.
 
  #14  
Old 01-26-16, 07:08 AM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,943
Received 43 Votes on 41 Posts
How was the charger modified from the factory? Without knowing exactly how that mod was done, including the internal components, we can't say what the correct connection is. Connection at 240V instead of 120V could potentially run 4 times as much power through the charger than it was designed for -- that might be a significant fire hazard.
 
  #15  
Old 01-26-16, 07:32 AM
Handyone's Avatar
Member
Join Date: Aug 2000
Location: U.S.
Posts: 5,450
Received 0 Votes on 0 Posts
Just friendly advice. You should make up your mind whether you want a 120v charge or a 240v charge, not try to use the same charger for both. Why would you need both when there could be a 240 charger available in the garage at all times?

Assuming the charger requires 30amps, it's not that difficult to run a 10-3 w/ ground cable.
The drywall can be fixed.
 
  #16  
Old 01-26-16, 03:50 PM
L
Member
Join Date: Nov 2015
Posts: 1,469
Received 70 Votes on 64 Posts
Depending on how modification was done and how circuit is wired, it may be possible to add a small 240V to 120V transformer to power both control and charger circuit from 240V.
But, as others said, without knowing the circuit of your charger cannot advise further other than running new line.
 
  #17  
Old 01-26-16, 10:18 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
Thanks to all who chimed in. I ran into my neighbor who is a commercial/industrial electrician and he took a look at the circuit board and thinks it would be best to just run a 10/3 from the box to the outlet. He said he would hook all the wires up if I did the wire run, so I am going to go that route.

Just out of curiosity, if I bonded the neutral and ground at the outlet, it technically should work with the 240 NEMA plug. This was according to the guy (different one than my neighbor) who provided the step by step on this modification. Does that sound right to you?
 
  #18  
Old 01-26-16, 10:37 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 35 Votes on 27 Posts
Does that sound right to you?
Absolutely NOT!

Further, anyone who advises connection the neutral and equipment grounding conductor ANYWHERE but at the SERVICE panel is someone that you should NEVER take advice from concerning electrical matters. :NO NO NO:

The reason why it is wrong is that it provides a parallel path for the returning (neutral) current on what is supposed to be a path for fault currents only. Doing so can under certain circumstances impose LETHAL voltage/current on any grounded/bonded metallic surface.
 
  #19  
Old 01-26-16, 10:42 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,150
Received 1,113 Votes on 1,033 Posts
Gootz..... we're going around in circles here. It's been well explained the risk of what you want to do.
 
  #20  
Old 01-26-16, 10:48 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
Let's just say that I like to weigh all of my options. Thank you to those who chimed in and explained the intricacies to my electro-lame brain. Like I said, I am going to be running 10/3 from the box to the outlet, so I'm doing it the proper way everyone is suggesting.

One thing I just remembered my neighbor said was that I should either upgrade my plugs to 30A versions or replace the 30A fuse with a 20A, so the circuit is all the same amperage. Not just from a safety standpoint, but from a code standpoint too. How necessary is this step? If I do end up doing this, would 12 gauge wire be sufficient for 20A?
 
  #21  
Old 01-26-16, 10:56 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,150
Received 1,113 Votes on 1,033 Posts
I don't know about upgrading your plugs but if you run #12 wire then it needs to be on a 20A breaker.

If you want a recommendation..... run 10/3 with ground. Use the same plugs and a 20A breaker. The larger wire will reduce voltage drop and allow you to increase charger size in the future. The charger should specify what size breaker should be used with it.
 
  #22  
Old 01-26-16, 11:01 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 35 Votes on 27 Posts
20 ampere and 30 ampere plugs or receptacles are not interchangeable. You have to have the corresponding plug/receptacle. #12 copper wire is proper for a 20 ampere circuit. If you have a 20 ampere circuit it is a code violation to have a 30 ampere plug or receptacle. If you have #12 wiring then it is a code violation to install 30 ampere fuses or circuit breakers or plugs receptacles EXCEPT for some special installations, primarily motor circuits and electric welder circuits. You r electric car charger does NOT fall into a special circuit that allows for higher rated fuses or circuit breakers than is normally allowed for a specific wire size.

In other words, if you have #12 wiring you may only use 20 ampere fuses or circuit breakers and 20 ampere plugs and receptacles. #10 wiring will require the 30 ampere fuses or circuit breakers and 30 ampere plugs and receptacles. You CAN always protect to a lower amperage with the #10 wiring. The fuses (or circuit breakers) will determine the proper rating for the plugs and receptacles.
 
  #23  
Old 01-26-16, 11:10 PM
T
Member
Thread Starter
Join Date: Jan 2010
Location: US
Posts: 78
Received 0 Votes on 0 Posts
Glad I asked. i will pick up the 20A breaker when I pick up the 10/3 wire, so if I ever want to upgrade the outlet to 30A it's an easy swap.

Thanks again!
 
  #24  
Old 01-27-16, 12:15 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,150
Received 1,113 Votes on 1,033 Posts
#10 wiring will require the 30 ampere fuses or circuit breakers and 30 ampere plugs and receptacles. You CAN always protect to a lower amperage with the #10 wiring. The fuses (or circuit breakers) will determine the proper rating for the plugs and receptacles.
The #10 wiring doesn't require the use of a 30A breaker or devices. That is optional.
 
  #25  
Old 01-27-16, 01:46 PM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,943
Received 43 Votes on 41 Posts
Just out of curiosity, if I bonded the neutral and ground at the outlet, it technically should work with the 240 NEMA plug. This was according to the guy (different one than my neighbor) who provided the step by step on this modification. Does that sound right to you
Technically speaking it would work, but it does not meet modern safety standards. A circuit with a bonded ground and neutral has the potential to put hazardous voltage levels on any exposed metal surfaces connected to that circuit. Historically you would see this with cloths dryers and cooking ranges that used to be connected with a shared ground/neutral wire. It would be relatively easy to get a shock by touching the metal appliance and a grounded cold water pipe -- in some cases the severity of that shock could be lethal. Code has prohibited this type of connection for 20 years on those appliances and much longer for other types of circuits. Given that the charger attaches to an even larger metal surface (Chevy) which gets wet and you put your whole body inside, I would guess that an even larger potential for shock would exist than would with a dryer or range.
 
  #26  
Old 11-02-17, 10:09 AM
C
Member
Join Date: Nov 2017
Location: USA
Posts: 1
Received 0 Votes on 0 Posts
Most 240v EVSE do not use neutral.
Mine is a dual voltage unit. It has a 240v L6-30 plug, and comes with an adapter to a 5-15 120v plug.
The adapter to a NEMA 14-x plug doesn't have a neutral pin, so it can be used on different amperage 14-x receptacles.
The 2018 Nissan LEAF comes with a similar 120v/240v unit. A 240v plug, and 120v adapter.
The internal circuitry runs in a range of 100-250v, World Compatible.
The output is whatever the input is. The charger in the car accepts two wire 100-250v.
 
Reply
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


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: