Wall charger installation at home - suggestions and recommendations? ⚡️⚡️

[Tommy]

So, a couple of things here, not to argue but just trying to understand and clarify.

The article referenced addresses amperage drop over a long run. Nicely explained, however the example given is "to deliver 60 amps to a service panel ". We are not trying to *deliver* 60 amps.

In my situation, and perhaps your's, I am attempting to deliver 48 amps to an EVSE on a 100 ft or less branch circuit. No more, no less, notwithstanding future proofing.

Using the 80% rule, (if I understand it correctly) I need to size my conductor at 57.6 amps for a 100 foot run , and/or 62.4 for a 150 ft run.

I would think a 60 amp breaker with a 6 AWG THHN in a conduit or 6 AWG MC would be sufficient to supply an EVSE at 100 feet safely.

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[timesinks]

Hmm, yes I see 6 AWG max on the Rivian EVSE hardwire. This is an issue as code (and common sense) requires the jump from 6AWG to 4AWG and even 3AWG for longer 60A runs (see https://learnmetrics.com/60-amp-wire-size/). I’m going to see if I can expand the wire holes in the EVSE, or worst case just trim some strands).

Don't trust everything you read on the internet. That article is objectively trash.

 

[ajdelange]

The article referenced addresses amperage drop over a long run. Nicely explained, however the example given is "to deliver 60 amps to a service panel ". We are not trying to *deliver* 60 amps.

You don't actually reference an article but none the less current does not drop over a long run. Voltage does and if the voltage drop is more than a couple of percent (as suggested in the code) you should probably go to a larger wire size which has lower resistance per foot resulting in less voltage drop. For example, the impedance of No. 6 copper(in PVC conduit) is .00044Ω/ft while that for No. 4 is .00021 Ω/ft. Forty eight amp EVSE must be on a 60 A circuit i.e. one that can deliver 60 A. For a 100' run there is a wire going to (black) and a wire coming back (red) from the panel. Each of those wires, if No. 6, will have a drop of 60*100*0.00044 = 2.64 V along its length so that if the panel voltage is 240V the voltage at the EVSE is 240 - 2.64 - 2.64 = 234.7 V. That represents a loss of 5.28/240 = 2.2%. As this is under 3% No. 6 is adequate. If you switch to No. 4 the drop will be 60*100*0.00021 = 1.26 V for a loss of 2.52/240 = 1.05%

In my situation, and perhaps your's, I am attempting to deliver 48 amps to an EVSE on a 100 ft or less branch circuit. No more, no less, notwithstanding future proofing.

Yes, we will, in fact, be delivering at most 48A but we are required to provide a 60A circuit to do that. The calculations are, thus, based on a 60A circuit.

Using the 80% rule, (if I understand it correctly) I need to size my conductor at 57.6 amps for a 100 foot run , and/or 62.4 for a 150 ft run.

You must size your conductor for a current rating of 60A in either case unless the voltage drop is greater than 3% in which case you would need to go to the next larger size. For a 150' run the voltage drop would be (150/100)*2.2 = 3.3% which is over 3% so you might want to go to No. 4. Note that there is no requirement in the NEC but there is an informational note before 210.19(A) that says that total loss in a branch circuit of 3% or less and total loss from service entrance to load of 5% or less generally leads to "reasonable efficiency of operation".

I would think a 60 amp breaker with a 6 AWG THHN in a conduit or 6 AWG MC would be sufficient to supply an EVSE at 100 feet safely.

Yes, it would but for 150 you might want to think about No. 4. Since, in fact, the current will actually be no more than 48A the actual drop seen in real use will be (48/60)*3.3 = 2.6% which is under 3%.

Some may be concerned about power loss. Assuming most of the impedance of the wire to be resistive the power lost in 150' of No. 6 at 48A is 150*2*0.00044*48*48 = 304.1 W. This makes the efficiency of the WIRE 97.4%. With 150' of No. 4 loss is 150*2*0.00021*48*48 = 145.1 W (98.7% efficient). For 100' the losses are, respectively, 202.7W (No. 6) and 96.7W (No. 4). For those of you who are watt hour pinchers loss in the wiring may be a consideration.

 

[Voronbrg]

I installed mine outside the home, I would say diy it if it's a short run.

 

[Acoustic71]

You don't actually reference an article but none the less current does not drop over a long run. Voltage does and if the voltage drop is more than a couple of percent (as suggested in the code) you should probably go to a larger wire size which has lower resistance per foot resulting in less voltage drop. For example, the impedance of No. 6 copper(in PVC conduit) is .00044Ω/ft while that for No. 4 is .00021 Ω/ft. Forty eight amp EVSE must be on a 60 A circuit i.e. one that can deliver 60 A. For a 100' run there is a wire going to (black) and a wire coming back (red) from the panel. Each of those wires, if No. 6, will have a drop of 60*100*0.00044 = 2.64 V along its length so that if the panel voltage is 240V the voltage at the EVSE is 240 - 2.64 - 2.64 = 234.7 V. That represents a loss of 5.28/240 = 2.2%. As this is under 3% No. 6 is adequate. If you switch to No. 4 the drop will be 60*100*0.00021 = 1.26 V for a loss of 2.52/240 = 1.05%



Yes, we will, in fact, be delivering at most 48A but we are required to provide a 60A circuit to do that. The calculations are, thus, based on a 60A circuit.


You must size your conductor for a current rating of 60A in either case unless the voltage drop is greater than 3% in which case you would need to go to the next larger size. For a 150' run the voltage drop would be (150/100)*2.2 = 3.3% which is over 3% so you might want to go to No. 4. Note that there is no requirement in the NEC but there is an informational note before 210.19(A) that says that total loss in a branch circuit of 3% or less and total loss from service entrance to load of 5% or less generally leads to "reasonable efficiency of operation".


Yes, it would but for 150 you might want to think about No. 4. Since, in fact, the current will actually be no more than 48A the actual drop seen in real use will be (48/60)*3.3 = 2.6% which is under 3%.

Some may be concerned about power loss. Assuming most of the impedance of the wire to be resistive the power lost in 150' of No. 6 at 48A is 150*2*0.00044*48*48 = 304.1 W. This makes the efficiency of the WIRE 97.4%. With 150' of No. 4 loss is 150*2*0.00021*48*48 = 145.1 W (98.7% efficient). For 100' the losses are, respectively, 202.7W (No. 6) and 96.7W (No. 4). For those of you who are watt hour pinchers loss in the wiring may be a consideration.

Geez Louise, I finally get it. Thanks so much for the continuing education.

 

[nc10]

'm having solar installed and the company just quoted me $3500 to wire the ev charger.

Not including the charger? I'd suggest getting a 2nd quote..... Seems high relative to my installation ($1500 plus the charger, but < 10 ft), and others I've seen here.

 

[M00v0vr]

Wiring /code gurus. What are the code/real life concerns and limitations for the number of wires through a conduit? I seem to remember somewhere, that also plays a role in this equation.

I ask because I have a main panel with a backup generator panel next to each other with an 1.5 conduit between them. It is stuffed with existing wires however it has room for my 6/2 THHN pulls. This would just be a pass thorough because my EVSE is one stud bay over.
My gut is telling me it would be better to run a new separate conduit, however that would be a PITA to do.

 

[NY_Rob]

^ IDK the volume formula, but if your gut is telling you "run another conduit" ... probably best off listening to it. Overheated wires can't be seen, running the EVSE wires in it's own conduit will at least give you peace of mind.

 

[ajdelange]

Wiring /code gurus. What are the code/real life concerns and limitations for the number of wires through a conduit? I seem to remember somewhere, that also plays a role in this equation.

The concern is that conduit traps heat. The requirements are found in tables in Annex C of the code (or get a copy of Ugly's at the big box store). For Schedule 40 PVC conduit you can have a maximum of 17 THHN wires.

This would just be a pass thorough because my EVSE is one stud bay over.
My gut is telling me it would be better to run a new separate conduit, however that would be a PITA to do.

Why not just run a piece of MC?

 

[M00v0vr]

The concern is that conduit traps heat. The requirements are found in tables in Annex C of the code (or get a copy of Ugly's at the big box store). For Schedule 40 PVC conduit you can have a maximum of 17 THHN wires.


Why not just run a piece of MC?

The panels are recessed and just above a bench, running MC would require taking that out. btw, the conduit is 2 inches total, I'll count wires when I get back up there tomorrow.

 

[ajdelange]

the conduit is 2 inches total, I'll count wires when I get back up there tomorrow.

What I don't know is what the rules are if you have different types of wire of different sizes.

 

[SACDFJC]

Rivian charger arrived and I picked up my wire, emt, breaker, couplers and lube from the local supply house. I'm looking forward to spending a few hours Saturday installing the charger. Now I just need my R1T.

 

[GEON]

just wrap red tape around that white conductor!

 

[Tommy]

PSA......For those of you with the Rivian Wall Charger who are wondering if you can access the internet via the ethernet connector located inside the charger cover, the answer is no. According to my guide, the ethernet connection is currently dormant as the software does not support it. It is intended for "future use". Currently the only option is via WiFi.

 

[Eeyore]

That's actually a code violation. Code requires that when a wire is visible and the conductor is being used for other than the purpose the wire's insulation color indicates the visible length of the wire must be wrapped in tape of the appropriate color. In this case the white (indicates neutral) wire is visible inside the EVSE enclosure. It is fine to use it for hot but it must be wrapped in red tape. The same must be done at the panel end.

The inspectors around here like to see just a little of the insulation when you re-identify the wire.

Perhaps but conduit just looks so much neater.

When installed by someone who knows how to bend it, I totally agree.

Meh. code is optional with DIY btw if we want to be code sticklers then that whip isn’t secured to code either.

You're right about the flex not being secured properly. You're totally wrong about code being optional. I've torn out so much home owner "code optional" wiring you'd think they just trying to burn down their house.

I don’t know what you’re talking about, MC is beautiful

MC is ugly AF. I wouldn't work on another job that was using MC, let alone install it where it can be seen.

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