[BennyP]

I recently moved into a new house and I am trying to figure out an inexpensive DIY charger solution. I am pretty handy but have very little electrical knowledge, i.e., I can change light switches, outlets, etc, but never done any major work. The new house is old but had a lot of upgrades done. The main panel (brand new) has a 2 pole, 20amp 240v breaker dedicated to the garage and the line runs to this old subpanel (photo attached). The line comes into the bottom of the subpanel and then out the top where it is distributed to various outlets in the garage, with the door opener plugged into one of them. It seems that they didn't run the ground from the main service, but this subpanel has a grounding rod running down beneath the floor of the garage (can see part of it in the photo, but none of the outlets in the garage are grounded (all 2 prong).

The subpanel is exactly where I want my charger to be. Can I use something like a 10 gauge power whip assembly to a 10-30 outlet? Can I trust the ground and set up a 14-50? (without running a ground from the main service). Would I run the wiring from "in front" of the subpanel? or take it after it goes through those old fuses?

I understand 240v 20amp wont charge that fast, but its better than a standard 120v outlet and my usual commute is very short and the car will charge overnight.

I know a lot of people will suggest I use an electrician but I just like doing things myself, and with COVID-19, I would prefer not to have anyone come to my house unnecessarily.

Thank you all in advance!

 

[joed]

You can not install a 30 amp receptacle on a 20 amp circuit.

 

[BennyP]

You can not install a 30 amp receptacle on a 20 amp circuit.

Thanks Joed. I understand this but the car allows me to adjust the current draw to whatever I want it to take, and at 80%, I can have it take only 16amps. Also, if it is possible to install what I am thinking, there is enough spare power at the main service to upgrade the breaker to 30amps. The wire run to the garage is 10 gauge as well.

 

[joed]

Then install a 20 amp receptacle.
You can't install a30 amp breaker unless the cables are 10 gauge.

Also that is not really a sub panel. It is fused disconnect.

 

[seharper]

I see a conduit pipe coming into that box, presumably from the service panel. That conduit pipe could have other wires also put in it. Since ground seems to be taken care of, you only need 2 wires. The question is what is that pipe? And will the extra wires legally fit inside it?

You cannot tack the EV onto this existing "whatever-it-is", because an EVSE requires a dedicated circuit. This stuff is already in-use powering your garage.

This is a MWBC; you might be able to move what's on both legs of the MWBC to only one leg, and use the other leg for a dedicated 20A/120V circuit. However that would only charge at 2KW. That probably won't cut it.

All in all this sounds like you need to skill up (don't try google learning, Google only answers questions and you don't know which questions to ask). Get a book, let it lay down the basics... then use Google/here/StackExchange to fill in the gaps/explore subjects deeper.

Fair chance you can get 30A/240V (6kw) out here without too much trouble. You may also be able to get 50A/230V (9.5kw).

I recently moved into a new house and I am trying to figure out an inexpensive DIY charger solution. I am pretty handy but have very little electrical knowledge

And then, you bought an EV

The new house is old but had a lot of upgrades done. The main panel (brand new) has a 2 pole, 20amp 240v breaker dedicated to the garage and the line runs to this old subpanel (photo attached).

Yeah, the trouble with buying a house and finding a brand new panel is the seller put that in to sell the house. And that usually means the cheapest tenant-grade junker possible. All the major makes (Eaton, Square D, Siemens and GE) are perfectly safe; the issue would be size: it's likely way too small, and completely full, possibly using "double-stuff" (duplex/quad) breakers. This may be a serious impediment.

That thing is a disconnect switch, which is disconnecting neutral, and is supplying a multi-wire branch circuit (MWBC) which is supplying the receptacles. Wire appears to be 12 AWG, which is 20A.

The line comes into the bottom of the subpanel and then out the top where it is distributed to various outlets in the garage, with the door opener plugged into one of them. It seems that they didn't run the ground from the main service, but this subpanel has a grounding rod running down beneath the floor of the garage (can see part of it in the photo, but none of the outlets in the garage are grounded (all 2 prong).

Retrofitting ground is perfectly legit. Further, any non-flexible metal conduit pipe (and some flexible) is allowed to carry ground. The top pipe is the good stuff, Rigid conduit. If this box is properly grounded, the Rigid will carry the ground downline as far as it goes. The bottom is one breed or another of flexible metal conduit. It's definitely not armored cable because arbitrary wires were put in it (no cable on earth has 2 black wires).

But that's good news; it means *you too* can put wires in it.

The subpanel is exactly where I want my charger to be. Can I use something like a 10 gauge power whip assembly to a 10-30 outlet? Can I trust the ground and set up a 14-50? (without running a ground from the main service). Would I run the wiring from "in front" of the subpanel? or take it after it goes through those old fuses?

Here's a table you have to keep in mind.

Breaker  -- Minimum wire size   -- Socket sizes allowed
15A      -- 14 AWG              --   15A  only
20A      -- 12 AWG              --   20A only for EVSE
30A      -- 10 AWG              --   30A  only
40A      -- 8 AWG               --   50A (40A sockets are not made)
50A      -- 6 AWG *             --   50A only
60A      -- 6 AWG               --   Hardwire only

* 8 AWG allowed if THHN in conduit AND both ends are on 75C terminations

Note how the socket sizes must always match the breaker size, which in turn calls out a specific size of wire. You can always use larger wire.

As to the retrofit ground, you're going to have to "walk the plant" and physically examine whether it really ties back to your service panel's main ground. Nonflex metal conduit is a valid path; water pipe is not.

I know a lot of people will suggest I use an electrician but I just like doing things myself, and with COVID-19, I would prefer not to have anyone come to my house unnecessarily.

Keep in mind everything you buy mail order also needs to be wiped down because it was handled by humans who generally can't afford to be sick, so they come to work anyway.

My advice generally is to skill up and get good at electrical; moreso now.

 

[BennyP]

Retrofitting ground is perfectly legit. Further, any non-flexible metal conduit pipe (and some flexible) is allowed to carry ground. The top pipe is the good stuff, Rigid conduit. If this box is properly grounded, the Rigid will carry the ground downline as far as it goes. The bottom is one breed or another of flexible metal conduit. It's definitely not armored cable because arbitrary wires were put in it (no cable on earth has 2 black wires).

Thanks @seharper for this! One question though, the box itself has a grounding rod going all the way into the earth. Do I need to run a ground all the way back to the main panel? Or can I ground the receptacle I am installing to this box which has it's own grounding rod? Thanks again.

 

[Jim Port]

A ground rod has nothing to do with the ground prong on a receptacle or grounding a box. It is not an effective ground fault path. The ground needs to be run with the circuit conductors.

 

[seharper]

Thanks @seharper for this! One question though, the box itself has a grounding rod going all the way into the earth. Do I need to run a ground all the way back to the main panel? Or can I ground the receptacle I am installing to this box which has it's own grounding rod? Thanks again.

No, you can't use dirt in place of a wire. I know it sounds super obvious when I say it like that, but the ground rods are actually not for returning *human* current; they're for returning *natural* current like ESD or lightning. There's no substitute for a ground *wire*. Though yes, you can ground the receptacle to the Grounding Electrode - that wire that runs from the panel to the ground rod.

Human current is very low voltage and high current (by God's standards), and the dirt can't deliver that much current. As a result a ground fault trying to return through *dirt* won't be able to trip the breaker for instance. Instead it will energize the dirt!