Questions for electricians

[Ultradog MN]

Going to install an outlet for a friend's new electric car this weekend.
Electrical questions here are a little like questions about best oil to use so I would appreciate the facts ie, code and not a lot of extraneous opinions.
The job:
240v
50 amp
3 conductors.
90 ft of thin wall conduit.
The cord for the car uses a typical 4 prong outlet like is used for an electric stove.
Simple.
My questions:
6 gage wire okay?
Some websites say 4 ga.

How bout a ground?
Recommended? probably.
But REQUIRED - as in NECA code?
I don't think it is.
If it is required can I use 10 gage?
I have enough green 10 ga THHN to do the job I could trade him.
Do you you think I can stuff that many wires in 3/4 conduit or would you go to 1 in?
I have the tools.
How would you pros wire this job?
Thanks

 

[old]

4 prong means 4 wires. If run 90 foot I'd say nothing less then 6 gauge wire 4 would be even better. Always better to do it over kill and be good then to do it under and be sorry

 

[Tony in SD]

Four #6 wires requires a 3/4 EMT. Four #4 wires requires a 1 EMT.

 

[MarkB_MI]

Ninety feet is a long run for AWG 6 wire at 50 amps. And unlike, say, a welder, your friend will be using his charger a LOT. Any voltage drop will translate to wasted energy that will show up on his electric bill. I'd go up to AWG 4; the power savings will eventually pay for the extra cost.

Conduit will provide the ground, but I like running a green ground wire inside conduit, just to be sure. I'm not aware that there's a minimum gauge specified by the NEC for ground wires inside conduit. The thing to remember is the ground conductor must be able to sink enough current to fault the circuit breaker in the case of a short. In other words, the conduit and ground conductor combined must be able to handle 50 amps long enough to trip the breaker.

 

[Geo-TH,In]

I'm not an electrician.

Metal conduit is usually something used in commercial wiring in my hood.

I think I've seen where metal conduit was uses as ground in the old days.

What do the commercial electricians say about that?

 

[RM-MN]

If you or your friend are not licensed electricians, hire one. You cannot legally do it for your friend and if any fault is found, you will be held liable. Your friend can do it for himself but if you are involved it sets you up for a lawsuit in the future.

 

[Ultradog MN]

I need to learn to write more clearly.
This is what I want to know:
If my friend called a big electric company and they did the job, how would they wire it?
What size conductors would they use?
What size conduit would they use?
Would they run a ground through the conduit and if so, what size wire would they use for that.
No speculation. No'overkill'. No homeowner looking stuff that works and could? pass inspection but...
Everything just right. So when/if the inspector came to look he would see what is actually a very simple job and know it was professionally done. The reason I don't use #4 or #6 NM wire is my friend doesn't want it stapled and drooping across his basement. Thinwall is easy to use and makes a nice, tidy job of it.

 

[DoubleO7]

Use #4 for every conductor including ground.
Put it in 1" pvc conduit.
using the emt for ground is not allowed in many local codes due to so many joints needed.

 

[Steve@Advance]

Legally, range cord could be used in residential, but it looks awful.

If I were doing it, I would run 3/4 EMT with RT connectors. RT(rain tight) just look better, run straighter.

Number 6 wire will be plenty, 2 #6 lines, a #6 neutral, and a #10 ground.

If the charger is outdoors, it will need to be on a ground fault breaker, weather proof boxes will need to be used. If any underground, use PVC conduit.

 

[knightstead]

The national electric code allows for EMT to be installed without a ground wire. I can pull up and post code number later if somebody would like me to. That said, it depends what a local building inspector wants. They are the AHJ ( authority having jurisdiction) and are allowed to go above and beyond code. I dont think its a good practice myself, youre relying on set screws at connectors and couplings to help continue your ground. All union electricians Ive worked around in St. Louis would pull a ground wire in the conduit.

 

[miangus]

It seems like they could build a charger so it was a 240 volt design, like a welder. That would allow for lower cost installations using three wires. If it has a four prong plug I would assume it had some 120 volt internals requiring a neutral return path. All the chargers I have seen (which is very few) where wired direct.

 

[John T]

Wow lots of good questions, I will offer my best recollection from my days as a Power Distribution Engineer but Im long retired and rusty on the latest NEC so NO WARRANTY, hold on here goes:

1) For 50 amps at 90 feet even if 6 Gauge would suffice I RECOMMEND 4 GAUGE COPPER to reduce Line Voltage Drop. Line Voltage Drop is a function of Current,,,,,,,Distance,,,,,,,,Wire size. I dont like it to be over 3 to 5%. NOTE You have to run the calculations to get the correct answer guesses here DO NOT COUNT

2) You say 3 Conductors HOWEVER you state 4 prong outlet ???????????????????? Here's the deal:

a) Straight 240 (no 120) requires two Ungrounded (Hot) Conductors PLUS a safety third wire Equipment Grounding Conductor

b) If the load requires BOTH 120 as well as 240 using what you say a 4 prong outlet, FOUR wires are necessary.

Two Ungrounded (Hot) Conductors
One Grounded (Neutral) Conductor
One Safety Equipment GroundING Conductor
NOTE a what you call a 4 prong outlet is known in the trade as a 3 Pole 4 Wire Grounding

SOOOOOOOOO IS IT STRAIGHT 240 0NLY (3 wires) ORRRRRRRRRRRRR 120 & 240 (4 wires) If it requires a 4 prong outlet then I recommend using ALL FOUR WIRES so you have BOTH 120 and 240 plus a required Neutral and required Equipment Ground

CAUTION NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

While in certain limited circumstances its possible if the correct terminations and bonds and splices and fittings are used and wired correct to use metallic conduit for the Equipment GroundING Conductor HOWEVER that's NOT for rookies only professionals and maybe in lighting circuits etc WITH PROPER TERMINALS AND CONNECTIONS which lay persons may not understand

THERES NO WAY (in my day at least) I WOULD SPECIFY OR DESIGN OR RECOMMEND using EMT conduit as a substitute Equipment GroundiNG Conductor for the installation you speak of However do as you please

THERES NO WAY I would run such service and NOT use a safety Equipment GroundING Conductor but do as you please

I dont have the conduit specs handy but 3 or 4, 6 or 4 Gauge Conductors in 3/4 conduit NOT BIG ENOUGH

SOOOOOOOOO figure if its 240 only (2 Hots + Ground) orrrrrrrrrrr 120/240 (2 Hots + Ground + Neutral) ???????????
I DO NOT recommend using conduit as Equipment Ground in this situation
NOTE its possible the Ground can be sized some smaller then the Hots, consult the NEC...
I WOULD NOT run this circuit without a proper Equipment Ground NO WAY !!!!!!!!!!!!!
IF the load requires a 4 prong outlet (3 pole 4 wire Grounding) I would run 120/240 2 Hots, Neutral, Ground
If the load is ONLY 240, you could get by with 3 wires, Hot Hot Ground

DISCLAIMER where fire and life safety are concerned you may want to consult professional NEC trained Electricians and Engineers and dont risk a life or fire on anything posted here me included as Im long retired.

Best wishes be safe and do whatever you please but this is my best professional advice

John T Longggggggggg retired Power Distribution Design Engineer so consult the NEC dont take my word for it

 

[dr sportster]

Is it allowed to use conduit as ground -- yes Does anyone actually do that NO A ground is run in almost every pipe run . You need 4 awg .in my opinion {electrician 30 years or more

 

[John T]

Good Questions:

If my friend called a big electric company and they did the job, how would they wire it?

If the load requires 120 as well as 240, of if they wired a 4 prong outlet, they would run FOUR Wires.....Two Hots, Neutral, Ground. If the load were 240 ONLY 3 wires may get you by

What size conductors would they use?

DEPENDS on the current as well as distance.....For 50 Amps likely 6 Gauge Copper MINIMUM but larger iffffffffff line voltage drop were excessive. They would compute the current and knowing it the wire size and distance they could compute line voltage drop to determine if 6 or 4 gauge or larger were required HAVE TO COMPUTE CANT GUESS...

What size conduit would they use?

DEPENDS on conductors used and how many conductors. The NEC explains this well. If 4 Gauge it needs to be bigger then if 6

Would they run a ground through the conduit and if so, what size wire would they use for that.

YES DEFINITELY they would run an Equipment Grounding Conductor per the NEC sized the same as Hots or can be downsized per the NEC

DISCLAIMER Im longgggggggg retired as a Power Distribution Engineer and rusty so no warranty but I tried my best to answer your question. Where fire and life safety are concerned consult trained professional electricians and engineers and dont risk life or fire on whats posted here me included

Best wishes, do it right be safe

John T

 

[M-MAN]

I would rethink the conduit. You have to consider air space when using it. There's a chart for conduit and you should reference it. Otherwise you will overheat the wire. Not safe or legal to just stuff it in. I used 1&1/4 pvc for my 50 amp welder line.

 

[Ultradog MN]

This job is for the guy I hunt with so I need to leave him with enough $ to buy beer and steaks at hunting camp in 2 weeks.
I ran this by a guy I went to HS with. He is a licensed master electrician with a dozen guys working for him. Shoulda called him first.
He said no ground wire legally required but they always pull one. He also said 10 ga in emt is suitable for a ground up to 60 amp.

So here's what I will do,

50 amp
90 foot run.
3/4 emt.
Three 6 ga conductors.
One 10 ga ground.
RT connectors (nod to Steve@)
Four prong range plug.
Safe, code, easy.
Now what oil is best for use in my Ford 4000?

 

[buickanddeere]

New EV's are going to 11Kw L2 home chargers, up from the 7Kw L2 home chargers.
Most L2 home charger cord kits use the 14-50R as that is the only heavy receptacle and circuit in the typical house.
Nobody worries about the charger not using the neutral. The four slot receptacle however must have the neutral ran to it along with the ground and two live lines. There always is some cheapskate however that wants to omit the neutral and/or the ground.
The 50 amp receptacle is good for up to 9.5Kw or charge rate.
The 11Kw charger draws 46 amps and should be on a 60 amp receptacle, wiring and breaker.
When installing the 14-50R receptacle . May as well install a 6-50R beside it if somebody ever wanted to plug in a welder etc.
If using T90 insulated wire . 3/4' conduit can be used for both four conductors of #8 or four conductors of #6.
I would go with the #6 incase a 11Kw charger is wanted someday.
Anyone who trusts the set screws on EMT to ensure a reliable ground . They are either very cheap, very naive or both. always Pull a ground wire.

This post was edited by buickanddeere on 10/21/2021 at 12:44 pm.

 

[John T]

CONGRATULATIONS like you said should of called him first lol

There ya go: Three 6 Gauge (suffices subject to current, distance, wire size, and allowable line Voltage Drop) if current
is too great causing excess line voltage drop you would have to upgrade to 4 Gauge Conductors

That satisfies 120/240 Volts running Two Hots, Neutral, 4 prong (3 Pole 4 Wire Grounding Receptacle)

The derated Equipment Grounding Conductor SURE BEATS USING THE CONDUIT FOR GROUND !!!!!!!!!!

HOWEVER I would specify larger conduit to make pulling wire much easier even if NEC says 3/4 suffices but
thats just me and how I was trained and practiced

What you call a 4 prong range plug your electrician calls a 3 Pole 4 Wire Grounding which is suitable for
120 & 240 having two Hots, Neutral, Ground

YOU DID GOOD GLAD YOU TALKED TO AN ELECTRICIAN

John T

 

[Ultradog MN]

B&D,

Good idea on an outlet for a welder...
But not for this guy.
My friend is a crack shot with a rifle.
But if he ever tried to weld something it
would be cracked and shot worse than
before. So we will skip that part.

Thanks to all who replied - even those who
provided worthless information.