Tesla charging station

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Fred B

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
sunbear said:
Thanks for everyone's helpful advice so far.

Does anyone know any electricians in the Essex County, New Jersey area who would be willing and capable of running conduit through studs? If so, please can you send a direct message to me with the contact details?

The electricians I've spoken to so far don't seem willing and confident about being able to do this. One electrician told me that if he were to use 90 degree conduit couplings (to make the turns required to follow the path from the electrical panel around the top of the side door and then down) then every 90 degree coupling would need to remain accessible through the sheetrock. He say that code requires this. Is this correct?

He said that the code requirement for accessibility doesn't apply if the pipe is bent using a pipe bending tool, but he doesn't think that there is enough space to be able to make the bends and avoid 90 degree elbow couplings (the studs are spaced 16" on center).

If couplings are necessary and need to remain accessible, how is this requirement typically achieved? Is an electrical box installed at each 90 degree turn and is a hole left in the sheet rock for each box?
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As said the 90o bend does not need accessibility but an LB would. The big consideration beyond this is the total number of degrees of turn the Elbows make between either boxes or conduit bodies. 358.26 indicate not more than a total of 360o of bends between pull points for EMT. If you can get between point A and point B and not exceed those limitations no pulling boxes needed.
 
Jon456

Jon456

Senior Member
Location
Colorado
sunbear said:
The electricians I've spoken to so far don't seem willing and confident about being able to do this. One electrician told me that if he were to use 90 degree conduit couplings (to make the turns required to follow the path from the electrical panel around the top of the side door and then down) then every 90 degree coupling would need to remain accessible through the sheetrock. He say that code requires this. Is this correct?

He said that the code requirement for accessibility doesn't apply if the pipe is bent using a pipe bending tool, but he doesn't think that there is enough space to be able to make the bends and avoid 90 degree elbow couplings (the studs are spaced 16" on center).
Click to expand...
You really need to find better electricians. Many residential electricians work almost exclusively with NM and have little to no experience bending conduit. Assuming two #6 hots and no neutral, you will need 3/4" EMT. (This size conduit will even give you room to upgrade to two #4 conductors if you ever need/want to upgrade your charger in the future.) A 3/4" EMT bender typically has a bending radius of around 5" and can produce a stub-up as short as ~7". No problem fitting that between studs with no need for condulets or pull elbows.

Here is a CAD drawing showing 3/4" EMT conduit with a 90° bend passing through a 1-1/8" hole in the center of a 2x4 stud. I've shown the conduit between two studs on 16" centers to illustrate how much installation room you have to work with. The straight connector is placed on the conduit stub after it's passed through the stud. Then continue with additional sections of straight conduit until you're past the side door in the garage wall and then stub down to the charger.

Conduit.png
 
S

sunbear

Member
Location
New Jersey
Occupation
Engineer
Thanks very much for the CAD drawing. A related question though is, how would you get the wire from the conduit into the Tesla Charger Wirebox.

The Tesla installation manual shows that the wires can enter from top, bottom or rear. How would one connect from the rear when the wires are coming from inside conduit? Would you connect the conduit to an electrical box with a mud ring and then sheet rock around the electrical box, pull the wires through and then mount the Tesla Charger Wirebox on top of the hole containing the wires in the electrical box?

Or would I be forced to connect from the Top Entry hole, in which case the EMT would need to run outside the wall instead of inside the wall...?



1636497286392.png
 
Jon456

Jon456

Senior Member
Location
Colorado
Or, run EMT inside the wall then put a kick in it just above the charger to bring the EMT above the surface of the sheetrock and enter the charger through the top KO.
 
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sunbear

Member
Location
New Jersey
Occupation
Engineer
Thanks for all the advice. I finally found an electrician that was proficient at pipe bending. Lesson learned: Don't limit yourself to the Tesla recommended electrician list.

The conduit and wire (#4 THWN-2) have been run. I just wanted to share a couple of photos to see what you all think
ConduitRun.jpg

Here's a close up of the electrical box. The wires to the Tesla charger are routed though a nipple on the electrical box
ChargerBoxCloseUp .jpg
 
acrwc10

acrwc10

Master Code Professional
Location
CA
Occupation
Building inspector
convert from emt to flex or sealtight in the wall and right in the back of the charger.
 

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sunbear

Member
Location
New Jersey
Occupation
Engineer
At the moment the wires come out of a nipple through the box into the back of the charger. Does this meet code?

Also the electrician has replaced a romex cable that I had for my other Tesla charger in the opposite corner of the garage with 4/3 MC cable + ground (neutral won't be connected). He intends to connect directly into the rear of this charger with a 90 connector. Does this meet code?

The reason I ask is that a different electrician told me that code does not allow going directly from MC to a plastic box like we have with a Tesla Charger and that one must first go via a box. Is that true? Thanks
 
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falconewk

Member
Location
Pasco, WA, USA
Occupation
Owner, Residential Journeyman
sunbear said:
At the moment the wires come out of a nipple through the box into the back of the charger. Does this meet code?

Also the electrician has replaced a romex cable that I had for my other Tesla charger in the opposite corner of the garage with 4/3 MC cable + ground (neutral won't be connected). He intends to connect directly into the rear of this charger with a 90 connector. Does this meet code?

The reason I ask is that a different electrician told me that code does not allow going directly from MC to a plastic box like we have with a Tesla Charger and that one must first go via a box. Is that true? Thanks
Click to expand...

I don't think this would work in your case because this fitting is only good up to 10/3 MC, but it allows for installation of MC into a plastic box. http://www.aifittings.com/catalog/f...lt-in-ground-for-retrofit-or-new-work/40RASTG

ETA: I would imagine you could maybe use a grounding bushing with a larger MC connector to make a MC to plastic box connection?
 
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steven765

Member
Location
NY/NH
Occupation
engineer
Still confused as too the logic behind #4 in conduit? Was this to go larger in the future and i missed that comment?

- 48A continuous load * 1.25 = 60A.
- 75deg terminals at panel, conduit, and box.
THHN 310.16 #6 at 75deg/C is good for 65A
OR
NM-B 55A for #6, since there's no 55A breaker 240.6(A), The next size up (60A) should be okay per 240.4 (B) as there's no violation of the exempted reasons.
#6 should have been sufficient?
 
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sunbear

Member
Location
New Jersey
Occupation
Engineer
steven765 said:
Still confused as too the logic behind #4 in conduit? Was this to go larger in the future and i missed that comment?

- 48A continuous load * 1.25 = 60A.
- 75deg terminals at panel, conduit, and box.
THHN 310.16 #6 at 75deg/C is good for 65A
OR
NM-B 55A for #6, since there's no 55A breaker 240.6(A), The next size up (60A) should be okay per 240.4 (B) as there's no violation of the exempted reasons.
#6 should have been sufficient?
Click to expand...
I wasn't aiming for the minimum and the cost difference for #4 was only about $40 more.
 
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steven765

Member
Location
NY/NH
Occupation
engineer
wwhitney said:
Sadly, it would be a violation of 215.2(A)(1)(a). I think the NEC is excessively conservative in this regard.

Cheers, Wayne
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How so? 215 is for feeders. I don't see the tesla charger as a SDS it's a listed appliance so that should fall under branch circuits. Same as a computer power supply.
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
steven765 said:
How so? 215 is for feeders. I don't see the tesla charger as a SDS it's a listed appliance so that should fall under branch circuits. Same as a computer power supply.
Click to expand...
Yes, and the OP was discussing a feeder to a panel.

For a branch circuit the same requirements are in 210.19(A)(1)(a), so my comments still apply.

Cheers, Wayne
 
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