GerryAZ
Gold Member
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Joined: Mon Nov 22, 2010 6:47 pm
Delivery Date: 12 Jun 2011
Location: Phoenix, AZ

Re: EVSE upgrade unit for 2016 and 2017 Leafs. (Hi power? Huh)

Sun Apr 02, 2017 7:17 pm

LeftieBiker wrote:
OP: the circuit has to be rated 25% higher than the continuous power draw. At 16A, that works out to 16*1.25 = 20A, and a power draw of 20A requires at least 20*1.25 = 25A. Outlets and breakers come in 20A and 30A varieties in that range.


The duty cycle is actually 80%, not 75%, so the circuit must be rated 20% higher than the device draw. I think it tends to get rounded up. And you can find 25 amp breakers, it's just harder.


Continuous load on a circuit is limited to 80% of the breaker and wire rating. This means that a circuit must be sized for 125% of the actual continuous load. Example: 24 ampere actual load X 125% = 30 amperes for circuit rating. 30 amperes X 80% = 24 amperes maximum allowable continuous load. Duty cycle is a different issue.
Gerry
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015

LeftieBiker
Posts: 6557
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: EVSE upgrade unit for 2016 and 2017 Leafs. (Hi power? Huh)

Sun Apr 02, 2017 8:21 pm

Yes, that's right. 'Duty cycle' is considered 100% for an EVSE. I used the wrong term.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

SageBrush
Posts: 852
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: EVSE upgrade unit for 2016 and 2017 Leafs. (Hi power? Huh)

Sun Apr 02, 2017 9:17 pm

LeftieBiker wrote:Yes, that's right. 'Duty cycle' is considered 100% for an EVSE. I used the wrong term.
You also missed the point:

Since code requires that continuous load be no more than 80% of circuit, if follows that circuit must be at least 1.25x continuous load. Check out the algebra:

If A = 0.8 B,
then B = A/0.8 = 1.25A
Last edited by SageBrush on Sun Apr 02, 2017 9:33 pm, edited 2 times in total.
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

LeftieBiker
Posts: 6557
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: EVSE upgrade unit for 2016 and 2017 Leafs. (Hi power? Huh)

Sun Apr 02, 2017 9:27 pm

We're talking past each other. Yes, 80% of the maximum load allowed for continuous use is the same as sizing the circuit for 125% of the continuous load. For everyone else confused by this, here is the NEC document:

http://ecmweb.com/basics/sizing-circuit-breaker
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

SageBrush
Posts: 852
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: EVSE upgrade unit for 2016 and 2017 Leafs. (Hi power? Huh)

Sun Apr 02, 2017 9:36 pm

LeftieBiker wrote:We're talking past each other.
We are not. You said
The duty cycle is actually 80%, not 75%, so the circuit must be rated 20% higher than the device draw.

This is incorrect, and I would like to see you correct your earlier post with an addendum.
As I show you above, 1/0.8 != 1.2, it equals 1.25
Or more specific to your error, if A is 80% of B, B IS NOT 120% of A. B is 125% of A

Algebra I, at your service.
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

LeftieBiker
Posts: 6557
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: EVSE upgrade unit for 2016 and 2017 Leafs. (Hi power? Huh)

Sun Apr 02, 2017 9:57 pm

Had you just quoted the line I messed up and noted the error I would have corrected that immediately. I didn't see it when you elaborated instead of just correcting. It's fixed now. When you've done a few hundred of these tedious posts in duplicate topics you'll better appreciate what us older-timers go through.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

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