A properly wired 4 wire 50 amp RV receptacle actually delivers up to 100 amps, 50 amps on each leg, with the neutral wire only carrying the difference between the two legs. How is the typical EV charger wired?


On Aug 10, 2008, at 7:35 PM, Andrew wrote:


This is all a bit irritating to me and to some of the people I have talked to at RV parks that have had to deal with inadequate power supplies.

When I plug into a 50 amp circuit, I think it is reasonable to expect 50 amps and not 40 amps.

It seems to me it is poor planning on the part of the manufacturers and/or the engineers who came up with the specs for the circuit breakers and related components.

Under the circumstances maybe a 65 or 70 amp circuit should be substituted for the 50 amp circuit so the expected 50 amps could be used.

What do you think?


From: [EMAIL PROTECTED] [mailto:listserv- [EMAIL PROTECTED] On Behalf Of Shawn Waggoner (FLEAA)
Sent: Sunday, August 10, 2008 7:11 PM
To: 'FLEAA Mailing List'
Subject: Re: [FLEAA] EV charging

Thanks for bringing this up David! This is a very important topic that I hope everyone pays attention too. If people are charging their EV’s at a higher rate than they should be, it could create a problem with breakers getting tripped. While this is not damaging, it may become bothersome to the provider of the circuit and get them to start questioning the charging of EV’s at their location. It could also be a problem if someone trips a breaker that they can’t get access to so it can be reset – then that circuit would not be available for the next person to use.

In more extreme cases, but highly likely, someone drawing more amps than they should can create a more serious safety issue. Drawing more amps than the 80% that David points out could result in melted wiring, or worse a fire. The last thing any of us, the club or EV’s in general need is a news story on how a charging EV caused a fire and property damage. Many of these circuits and wires are old, with potentially weaker connections and higher resistance.

Please heed David’s warning. Always check to see what type of power is available on the circuit, not just by looking at the outlet type but asking what type of breaker it is and if anything else is sharing the connection, and set your charger to use NO MORE than 80% of that circuit. It is tempting to want to charge at a higher rate to be done sooner, but please, take the few extra moments and keep everyone safe and EV’s out the news (at least for bad news!).


Shawn Waggoner

Florida EAA

From: [EMAIL PROTECTED] [mailto:listserv- [EMAIL PROTECTED] On Behalf Of David, FloridaAME
Sent: Sunday, August 10, 2008 5:55 PM
To: 'FLEAA Mailing List'
Subject: [FLEAA] August Meeting and charging

While the meeting yesterday had no real topic I learned a lot about public charging in a discussion with Charles. I think others learned a little about the implications of the National Electric Code Article 625 which is about charging EV’s and conduction charging sites.

After the meeting I was thinking about something Andrew said about charging his EV at various sites and having to change the vehicles charge rate. Back to the National Electric Code, if you have a 50 Amp circuit breaker and 50 amp wiring, a 50 amp receptacle, you can only use 80% of it or 40 Amps. The missing 20% allows for variations in the circuit breaker manufacturing, things heating up, and a safety factor so the breaker does not trip.

The other thing is when a 50 amp receptacle is used, many people expect a 50 amp breaker. But the 50 amp 14-50P receptacle has become the standard or the RV industry but actually supplies vary 30, 40 and 50 Amps.

For no problems ask what amperage is available and use 80% of that.

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