50 Amp Line to use supplied 240 cord on 2018?

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Newporttom

Well-known member
Joined
Jan 4, 2011
Messages
115
Location
Saint Johns, FL
Just traded in 2012 for 2018. I have an existing 240 volt line that I used with my 2012 with a modified EVSE. It's either a 20 amp or 30 amp line. Can I use that line (once an electrician modifies the plug), or do I need a 50 amp line?
 
Newporttom said:
Just traded in 2012 for 2018. I have an existing 240 volt line that I used with my 2012 with a modified EVSE. It's either a 20 amp or 30 amp line. Can I use that line (once an electrician modifies the plug), or do I need a 50 amp line?


50A circuit for a 50A outlet . Thee is no way you can use your existing circuit if it is 30A. Ask a qualified and licensed electrician in your area for your answer and be sure they will certify it will pass inspection. You will get many creative answers here however you should follow your local code not what others may say. You can also email your building department for an answer likely.
 
The circuit is dictated by the plug on the device. It does not matter if the EVSE is 5A, if it has a 50A plug it needs a 50A circuit. The reason is that someone could come along and plug a device in that outlet that would draw 40A. You may also have additional requirements based on local codes.
 
EVDRIVER said:
if it has a 50A plug it needs a 50A circuit. The reason is that someone could come along and plug a device in that outlet that would draw 40A.
That may be your reason, but the NEC doesn't require it. As the EVSE included with the Nissan Leaf requires only a 40A circuit, it is acceptable to install a 40A circuit with a 14-50 receptacle.

Cheers, wayne
 
wwhitney said:
EVDRIVER said:
if it has a 50A plug it needs a 50A circuit. The reason is that someone could come along and plug a device in that outlet that would draw 40A.
That may be your reason, but the NEC doesn't require it. As the EVSE included with the Nissan Leaf requires only a 40A circuit, it is acceptable to install a 40A circuit with a 14-50 receptacle.

Cheers, wayne


The NEC does not conduct inspections or set local codes that's why the "N" means National not local. There are plenty of people that have failed inspections for this very reason, not my reason. Please show me where the NEC says you will pass a local inspection with that configuration. There are many Tesla and other EV owners that can attest to their electricians rewiring their outlets because of this misconception. Some cities also have very specific (and ridiculous) additional requirements for EV outlets which also include such things like a cut off switch within a certain distance which is also NOT required in the NEC. Confirming this with the local building department makes more sense than saying the "NEC says its ok". To be clear, there are inspectors that require 50A circuits on 14-50 outlets for reasons from "that's how we do it" to "the city requires this on all EVs" or "we no longer make this exception anymore". I have heard all of these reasons personally and there is no point arguing the NEC. This is why I always tell people to check the local code or make the electrician responsible for the permit passing at their cost. FYI- Berkeley is pretty lax on this but they are terrible on other commercial electrical matters because of recent events.
 
That's all fine, but a few points:

1) Our experience in California isn't very useful to the OP in Florida. Many jurisdictions adopt the National Electrical Code as is, but of course it is important to check for local amendments.

2) In California, jurisdictions can only amend the California building codes for "local climatic, geological, or topographical conditions," and those amendments have to be filed with the state. A list of jurisdictions that have done this is available here as a PDF: http://www.bsc.ca.gov/Rulemaking/LocalCodeOrdinances.aspx Are you aware of any jurisdiction that has amended the California Electrical Code to prohibit a 14-50 receptacle on a 40 amp circuit?

3) Misinformed inspectors making up requirements is always a problem.

Cheers, Wayne
 
The important thing the OP needs to tell their electrician is the max sustained load is 7.2KW & the electrician can ensure the correct wire size/gauge & breaker is utilized.

Don't forget that for an extended wire run an upsized wire will be required.

Also the OP or anyone having electrical work done may want to consider having 60 amps or even 80 amps worth of service if paying for a wiring job for future use because the cost of the larger wire & sub-panel is comparatively small when factored into the entire job & would allow for other circuits to be added or a future EV with a potential 10-20KW charge rate as battery tech improves over the next 10-20 years.
 
All I know about electricity is not to lick my fingers and stick them in a socket.... But I think I figured out from reading the thread, that the second number on the plug means the amps. So a 14-50 means a 50 amp line.
 
wwhitney said:
That's all fine, but a few points:

1) Our experience in California isn't very useful to the OP in Florida. Many jurisdictions adopt the National Electrical Code as is, but of course it is important to check for local amendments.

2) In California, jurisdictions can only amend the California building codes for "local climatic, geological, or topographical conditions," and those amendments have to be filed with the state. A list of jurisdictions that have done this is available here as a PDF: http://www.bsc.ca.gov/Rulemaking/LocalCodeOrdinances.aspx Are you aware of any jurisdiction that has amended the California Electrical Code to prohibit a 14-50 receptacle on a 40 amp circuit?

3) Misinformed inspectors making up requirements is always a problem.

Cheers, Wayne

My point is not if they care changing the code but enforcing a higher requirement. I'm not sure they need to change the code to require a 50A breaker or disconnect. Even if they do many inspectors make the call and you can debate it all you want but that's batter better fought on bigger issues. Why argue an create other issues when changing wire or adding something is usually easy. Most electricians in the SF proper area will only put in 50A circuits regardless, I asked two the other day and both said they will not install a 40A breaker even a the customers request. If the panel supports it and there are not other ramifications it is really foolish not to have the headroom regardless. As an odd example I think there is one city that will not allow any Romex anywhere only flex, talk about old politics. I tired to get a second meter and SF declined me because they were banning them for single family homes thinking it would be used for in in-law unit. Stupid rules all over.

Some cities it's as easy as an outlet permit where some require plans, new smoke and CO detectors, etc. Some cities charge huge permit fees for an EV outlet but if it is a dryer it is completely different, go figure. Municipalities should make it more affordable for a permit to prevent carless DIY jobs not pad permits because the work EV is used. On the flip side many electricians are gouging for this or charging more because of more complicated requirements or site visits. Since CA was an early adopter site I would expect tighter requirements to expand out to other states with EV demand increasing.

Glad I don't live in Fremont:

https://fremont.gov/DocumentCenter/View/25378/Electric-Vehicle-Charging-Stations?bidId=
 
Newporttom said:
All I know about electricity is not to lick my fingers and stick them in a socket.... But I think I figured out from reading the thread, that the second number on the plug means the amps. So a 14-50 means a 50 amp line.


That's a common post installation technique for testing the outlet. (that's a joke)
 
The 2018 is a Leaf like any other... You don't need to change the setup you had for you old one>>>>>..... Unless you were using a slower EVSE (like a 16-20 amp charger).

For home use, the fastest charger is the 30 amp EVSE which charges at 6.6 kwh.... Since that one uses 30 amps, you may want to install a 40 amp breaker to protect the wiring ... At this point in technology, no one needs a 50 amp breaker because there is no 40 amp evse or car that can handle more than the 6.6 kwh charge...
 
powersurge said:
WetEV said:
powersurge said:
car that can handle more than the 6.6 kwh charge...

Lots of cars can handle more that 6.6kW charging rate. Perhaps you mean no LEAFs can...

What car? Forget about Tesla...
Off the top of my head, besides Tesla-powered vehicles like gen 2 Rav4 EV and Mercedes B-Class ED, these US-market non-Tesla-powered vehicles have OBCs above 6.6 kW: BMW i3, Chevy Bolt and '19 Chevy Bolt (optional) and I think VW e-Golf. This is probably not a complete list.
 
powersurge said:
The 2018 is a Leaf like any other... You don't need to change the setup you had for you old one>>>>>..... Unless you were using a slower EVSE (like a 16-20 amp charger).

For home use, the fastest charger is the 30 amp EVSE which charges at 6.6 kwh.... Since that one uses 30 amps, you may want to install a 40 amp breaker to protect the wiring ... At this point in technology, no one needs a 50 amp breaker because there is no 40 amp evse or car that can handle more than the 6.6 kwh charge...


You mean no Nissan. It is very common for people to move and have a Tesla plugged into a 14-50. That means you are drawing 40A on a 40A breaker which is more than the 80% rule. Since most 40A breakers are not rated for continuous use as the connectors on that type of breaker are designed so they do not come loose. Ones that do then create high resistance and then potential big issues. I have seen this heat related failure on more than one overloaded breaker.
 
EVDRIVER said:
It is very common for people to move and have a Tesla plugged into a 14-50. That means you are drawing 40A on a 40A breaker which is more than the 80% rule. Since most 40A breakers are not rated for continuous use as the connectors on that type of breaker are designed so they do not come loose. Ones that do then create high resistance and then potential big issues. I have seen this heat related failure on more than one overloaded breaker.
To clarify this, there are two separate issues with using a 40A breaker at 40A continuously:

1) With a 40A continuous load, all the connections in the circuit are going to be put to the test. Any poor connections are going to quickly develop hot spots, and if not caught could start a fire. The same is true of a 32A continuous load on the circuit, but only 64% as much power would be dissipated at the poor connections. That would still be enough to cause most poor connections to show up, but obviously there could be a marginal connection that survives 32A but not 40A.

2) For a 40A breaker in the worst case environment (40C ambient temperature, in a panel full of other breakers), the thermal trip is only designed to hold at 32A continuously (80%). If the continuous current exceeds 32A, the thermal trip mechanism may trip. That thermal trip mechanism is the only part of the circuit that is not rated for 40A continuous.

Because of (2), when installing a 40A continuous load, it is necessary to specify a 50A breaker. And because the wiring needs to be adequately protected by the breaker, the wiring needs to be rated at 50A. The result will be a circuit in which everything is rated for 50A continuously, except the thermal trip rating of the breaker, which will be rated to hold at 40A continuous.

It is a poor product design choice that the Tesla Mobile Connector doesn't offer an option to plug into a 14-50 receptacle while restricting the EVSE current to the 32A maximum suitable for a 40A circuit.

Cheers, Wayne
 
wwhitney said:
EVDRIVER said:
It is very common for people to move and have a Tesla plugged into a 14-50. That means you are drawing 40A on a 40A breaker which is more than the 80% rule. Since most 40A breakers are not rated for continuous use as the connectors on that type of breaker are designed so they do not come loose. Ones that do then create high resistance and then potential big issues. I have seen this heat related failure on more than one overloaded breaker.
To clarify this, there are two separate issues with using a 40A breaker at 40A continuously:

1) With a 40A continuous load, all the connections in the circuit are going to be put to the test. Any poor connections are going to quickly develop hot spots, and if not caught could start a fire. The same is true of a 32A continuous load on the circuit, but only 64% as much power would be dissipated at the poor connections. That would still be enough to cause most poor connections to show up, but obviously there could be a marginal connection that survives 32A but not 40A.

2) For a 40A breaker in the worst case environment (40C ambient temperature, in a panel full of other breakers), the thermal trip is only designed to hold at 32A continuously (80%). If the continuous current exceeds 32A, the thermal trip mechanism may trip. That thermal trip mechanism is the only part of the circuit that is not rated for 40A continuous.

Because of (2), when installing a 40A continuous load, it is necessary to specify a 50A breaker. And because the wiring needs to be adequately protected by the breaker, the wiring needs to be rated at 50A. The result will be a circuit in which everything is rated for 50A continuously, except the thermal trip rating of the breaker, which will be rated to hold at 40A continuous.

It is a poor product design choice that the Tesla Mobile Connector doesn't offer an option to plug into a 14-50 receptacle while restricting the EVSE current to the 32A maximum suitable for a 40A circuit.

Cheers, Wayne


The hard wired units do but not the mobile connector. You also make a point that some here can't seem to embrace. Often people install a 40A circuit on a 14-50 because they may have a load at 32A. However they may sell the house or get a Tesla and plug in a 40A unit because the "outlet works". This is the exact reason all outlets really should have the circuit to match not to mention the added safety factor for a 32A device. Heating and cooling on breakers with high loads can lead to big issues. I'm not clear on why people recommend the lowest requirement solution when it comes to safety. This is exactly the reason some cities are enforcing stricter requirements on EVSE outlets.
 
EVDRIVER said:
It is very common for people to move and have a Tesla plugged into a 14-50.

My Tesla Model 3 LR mobile EVSE has a 14-50 plug but cannot pull more than 32 Amps. The car OBC is rated for up to 48 Amps.
Tesla sells plug adapters for its EVSE to use a variety of outlets. The adapter must be setting the EVSE to a lower Amp draw. I don't know if Nissan has something similar for lower amperage L2 (240v) outlets.
Alternatively, can either the Nissan LEAF or the mobile EVSE be configured to draw a lower amperage ? If so and OP is happy with that charging rate, he could consider buying a generic adapter to e.g. a 6-30 plug and perhaps not incur the cost to upgrade the outlet.

----
This thread has become a religious fight, so I'll throw in my oar and say that the safest approach is to have a 50 Amp circuit and breaker behind a 14-50 outlet.

I am not an electrician.
 
Just to add some more details, the Tesla Mobile charger supplied with S/X/3 is a Gen 2 charger that limits the charge rate to 240v/32 amps, but the older Gen 1 chargers were able to supply 240v/40 amps.

Phil
 
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