Wiring gauge for 30A L2 EVSE? Electrician used #10?

Hi all,

I bought a Gen 2 Schneider EVLink charger (Gen 2.5 here, for reference: http://www.homedepot.com/p/Schneider-Electric-EVlink-30-Amp-Generation-2-5-Enhanced-Model-Indoor-Electric-Vehicle-Charging-Station-EV230WS/203670265 ) a few years ago and had our electrician install it for our 2012.

After he installed it, I was cleaning up some debris left over and noticed some scraps form his install were #10 copper wire. I asked him about that (because as I recall the instructions said #8 copper or aluminum) and he said that #10 copper is fine to carry 30A (this is what dryers use too, apparently).

Fast forward to a couple of months ago and during our PV install I was talking to their electrician and he said that loads that run for >2 hours are considered "continuous" loads and thus you need to derate their conductor carrying capacity by some factor (I think 20%)?

In any case, now that we are looking to trade in our 2012 with a 3.6 kW charger and buy a 2015 with the 6.6kW charger (and probably in the next day or so), I'm a bit worried that the #10 copper isn't sufficient/safe for the EVSE installation. Especially with temperatures still in the 90's...

So, does anyone know if #10 copper is safe/up to code for a "continuous" load in this case? Or, should I ask him to come back out and re-install using #8 copper? I think the actual current requirement would be a bit less at 28A, but I want to be safe here and not risk a fire or anything.

Thanks!

It needs to be #8 for 30 amps with a 40 amp breaker.

#8 at least.
+1

The specs according to the link say's "average amps 30" no idea what that means, however being a master electrician I can tell you this: The 13 Leaf charger is 6600 watts /240 volts = 27.5 amps, on a 2012 it may be 3300 watts/240volts =13.75 amps. #10 awg wire will happily conduct 30 amps all day, however the 30 amp breaker protecting that wire will not like life if the draw is more than 80% of 30 amps= 24 amps on a continuous basis ( more than 1 hour in a 2 hour period) . therefore in situation 1 (13 Leaf) you would run a #8 awg conductor protected by a 2P 40a breaker (max 32 amp cont. load), and in situation #2 (12 Leaf) a #10 awg conductor protected by a 2P 30 amp breaker ( max 24 amp cont. load) WOULD SUFFICE with this note: How did this "electrician" know that your 2012 had only a 3300 watt charger? The proper method is to use the maximum rating of the equipment (30 amp) and feed it with #8's on a 2P 40A breaker. You are temporarily safe , but the equipment has been wired in a way which limits it below its maximum rating . And yes the Leaf should charge for more than 2 hours continuously (assuming a healthy battery).

Thanks everyone for the replies.

Yeah, #8 for 30A continuous draw with a 40A breaker makes sense. I wish I would have pressed him on it when he was here originally. Shouldn't have taken his word that #10 would suffice.

And to answer other questions, he didn't base the gauge of wire based on charger capacity (2012 vs 2013+), but rather on the output of the device (30A). I guess he didn't derate for continuous use.

So, what are the continuous (and non-continuous) current carrying capacities (under "normal" household conditions) of #8 and #10 copper wiring? Our wire runs from the charger in the garage, up the wall, through to attic, and then outside and down to the panel, so it gets hot up there but nothing extreme.

Also, the conduit that the EVSE wire runs in now also has another run; much smaller capacity that just feeds a single 120V outlet in the garage for our deep freezer. I'm not sure of the conduit size, but with this other run, do we need to derate further to account for more crowding in the conduit? Forgive me, but I'm starting to second guess the electrician and again, want to make sure this is safe.

Thanks a lot!

BoulderLeaf said:

So, what are the continuous (and non-continuous) current carrying capacities (under "normal" household conditions) of #8 and #10 copper wiring?

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For continuous loads, just multiply the load by 125% and then size the wires normally.

#10 copper must be protected at 30 amps or less, but the base ampacity for temperature and conduit fill derating may be higher depending on the wiring method (30, 35, or 40 amps).

#8 copper has an ampacity of 40, 50 or 55 amps, depending on the wiring method.

BoulderLeaf said:

Also, the conduit that the EVSE wire runs in now also has another run; much smaller capacity that just feeds a single 120V outlet in the garage for our deep freezer. I'm not sure of the conduit size, but with this other run, do we need to derate further to account for more crowding in the conduit?

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Yes, you need to derate to 80% for 4-6 current carrying conductors in the same conduit or cable. However, depending on the wiring method (the insulation temperature rating), you can use those higher ampacities above as the base before multiplying by 80%. So likely it is OK.

For a more complete answer, you need to provide the sizes of the loads, the breakers, and the wires as well as the wire type (THWN?) Also, please estimate the maximum temperature in the attic where the wire is run, for temperature derating.

Cheers, Wayne

I don't see any install instructions online for that unit, but I would think there should be a way to set it to allow 24a Max. Maybe a dip switch or jumper. You won't really miss those extra three amps anyway, especially after being used to a MY '12. I also ran #10 so I just have my EVSE set to 24a.

I don't know about the theory, but our electrician used 8G wire and 40amp breaker for our Aerovironment EVSE "charge station." I live in Palo Alto, and the city is VERY particular about codes, permits, and inspections.

BoulderLeaf said:

... Yeah, #8 for 30A continuous draw with a 40A breaker makes sense. I wish I would have pressed him on it when he was here originally. Shouldn't have taken his word that #10 would suffice.

And to answer other questions, he didn't base the gauge of wire based on charger capacity (2012 vs 2013+), but rather on the output of the device (30A). I guess he didn't derate for continuous use. ...

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How did it pass inspection? The inspector should have caught a mistake like this. You need to have it redone, or dial your EVSE down to 24a.


Please don't tell us you let the guy skip the permit process. It's there to protect you and your house.

#8!!! that's why i went with this unit

http://www.clippercreek.com/store/product/hcs-30-24-amp-ev-charging-station-25-ft-cable/

I have a detached garage with a #10 50 Ft. run already and would have had to rewire the feed with an #8 or #6 with that unit or equal. The additional charge time a non issue for me charging overnight.

It all so depends on the circuite length for voltage loss

10 guage is fine for a short run as you won't get apreciable drop (Or heat)

I used 10awg on my work rig due to short run in open air, and at home same thing it is a 25 foot run open air.

8awg is a CMA (Cover my ass) rating to ensure under the most incompitent conditions there is assured head room that nothing will happen. Good policy and no reason not to use 8awg other then to be cheap (Which in my case was the main reason I chose to do it, but I have the knowledge base to do it in a way there was no risk)

So long as it is complient with the local code and it works good with less then 5% voltage drop (3% ideal) your golden.

Every one ells covered the finer details lovely.

Thanks for the great feedback everyone.

I'm having the electrician come back out to fix as a "warranty" issue, and will verify that all is OK.

When I spoke with him on the phone, he sounded like he had wired for expected usage of the 3.6kWh charger (which is clearly wrong - always wire for max power rating of fixture).

BoulderLeaf said:

... When I spoke with him on the phone, he sounded like he had wired for expected usage of the 3.6kWh charger (which is clearly wrong - always wire for max power rating of fixture).

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Get a permit and have the job inspected. It's the law pretty much everywhere. That would have prevented this.

If the device was set by the electrician to 24a, this setup was perfectly fine and would have passed inspection just fine.

BoulderLeaf said:

Thanks for the great feedback everyone.

I'm having the electrician come back out to fix as a "warranty" issue, and will verify that all is OK.

When I spoke with him on the phone, he sounded like he had wired for expected usage of the 3.6kWh charger (which is clearly wrong - always wire for max power rating of fixture).

Click to expand...

That's good. If the electrician had read the installation instructions (found online, but surely included with the unit, also) , he would have seen:

Power Requirements
— Input Voltage: 208–240 Vac (See Figure 4 on page 4.)
— Input Current: 30 A
— Frequency: 60 Hz
— Feeder Circuit Breaker: two-pole, 40 A

NOTE: A ground fault circuit interruptor
(GFCI) circuit breaker will override the
automatic reset function built into the
charging station.

NOTE: Use AWG 8 copper or aluminum
wire rated 90 degrees C or higher.

I've had issues with less-than-competent electricians as well. I think, if you call up a big company to do a simple wire run, they'll just send over their most junior guy while everyone else is off doing multi-day commercial stuff. The guy that just installed a plug for my EVSE was going to put a 30-amp breaker on it until I asked him about it. He said is was a 30-amp device, so he's wiring it to 30 amps. I told him that's a continuous load, so you have to have 20% headroom and he looked at me like I was an idiot, saying that it would violate the UL listing if he used a 40-amp breaker, etc. I finally had to go to the damn product page for the EVSE and print it out for him. Luckily it had the recommended circuit amperage listed right there or I'd be replacing the damn breaker myself today (and possibly re-running wire!).

Next time I'm doing it all myself. This **** is not that complicated, and if you can only get someone with 6 months experience anyway, what's the point? It should be free labor if I'm training an apprentice. Plus, it gets inspected regardless, so you'll have someone who really knows what's up making sure it's safe.

Bill, I searched and couldn't find the install instructions for that unit on their webpage. Does that unit have any pilot level settings (I.e. Can it be set to advertise different charging levels? I looked at that unit at Home Depot years ago and I can't remember if it did.

Thanks
Alan

Alu wire is garbage! 6 awg alu is equivelent to 8 copper, then you have cold flow and oxi issues to deal with, just do not do it! friends don't let friends do Alu wiring!

Copper only!, clean and torque to specs!!!!

pkulak said:

I've had issues with less-than-competent electricians as well. I think, if you call up a big company to do a simple wire run, they'll just send over their most junior guy while everyone else is off doing multi-day commercial stuff. The guy that just installed a plug for my EVSE was going to put a 30-amp breaker on it until I asked him about it. He said is was a 30-amp device, so he's wiring it to 30 amps. I told him that's a continuous load, so you have to have 20% headroom and he looked at me like I was an idiot, saying that it would violate the UL listing if he used a 40-amp breaker, etc. I finally had to go to the damn product page for the EVSE and print it out for him. Luckily it had the recommended circuit amperage listed right there or I'd be replacing the damn breaker myself today (and possibly re-running wire!).

Next time I'm doing it all myself. This **** is not that complicated, and if you can only get someone with 6 months experience anyway, what's the point? It should be free labor if I'm training an apprentice. Plus, it gets inspected regardless, so you'll have someone who really knows what's up making sure it's safe.

Click to expand...

Never underestimate human incompetence. During my early homeowner days when I was naive and trusted people I needed to add an outlet in the garage and also wire an indoor whirlpool tub that had an in-line water heater. So I hire a guy someone recommended for the job which he completed and I never had any thoughts about it afterwards. I didn't pull a permit out of my own ignorance so no city inspection was done, my fault. 15 years went by, I found one of the GFCIs for the whirlpool tub needed to be replaced, and I'm also adding GFCIs in the kitchen and the garage. The outlet in the garage he added was wired with #14 onto a 20A circuit, even if not immediate fire danger as I never ran any high loads on that outlet definitely a red flag. So I go and check the panel how he wired the tub, and this idiot ran 2 20A #12 circuits with a shared neutral from the same leg! It is fortunate that the whirlpool tub has seen very little use over these years as the equipment was using about 25A total and bad things could definitely happen.

XeonPony said:

Alu wire is garbage! 6 awg alu is equivelent to 8 copper, then you have cold flow and oxi issues to deal with, just do not do it! friends don't let friends do Alu wiring!

Copper only!, clean and torque to specs!!!!

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Yes, but newer AL alloys are better than what they used in the 60s, and when used with AL rated terminals and anti-oxi paste are probably as safe as copper if electric code allows. Still, for an EVSE install there is no point as savings are just not there and if hard-wired the terminal block inside the EVSE is likely not rated for AL, so copper it is.