Wiring assistance requested

I have two 110 volt circuits in my garage that are fed by a 10/3 buried wire.

As it comes into the garage, it goes into a 4" junction box where from one side circuit A leaves and from the other side circuit B leaves. Each circuit feeds separate things. On A are florescent lights, garage door opener, outside security light and two motion detector lights. Circuit B is for the charger that came with the Leaf. Both circuits share the common ground.

In the 200 amp circuit breaker panel in the basement there are two separate breakers, each 15 amps and labeled as Circuit A and the other one as Circuit B. They could be pulling from the same side of the incoming 220. I'd have to change them anyway if I were to install an 220 volt EVSE in the garage by putting in a double breaker.

I realize a 30 amp ESEV would be pushing things, even if there were to be no additional draw coming from the 110 circuit A and circuit B, as the 30 amp EVSE will draw about 27 amps, so I think I had better stay with a 20 amp EVSE, like the Clipper Creek.

If I do this, I plan on running 10/2 from the junction box, taking one lead from the hot red wire and the other from the hot black wire, (about a 30 foot run, ) to the other side of the garage where I would run it into a 20 amp breakered disconnect switch. From this disconnect switch I would wire the Clipper Creek or install a dryer female outlet for the male plug on the Clipper Creek. (I am thinking about making it portable so I could take it to my sons where he would install a similar outlet off his air conditioner. (Wouldn't run them both at the same time.)

Is it necessary to have a ground on the Clipper Creek? If so I could make the 30 foot run with 10/3, rather than 10/2 and pick up the ground from the neutral on the incoming 10/3.

Your thoughts?

Thanks.

greengate said:

I realize a 30 amp ESEV would be pushing things, even if there were to be no additional draw coming from the 110 circuit A and circuit B, as the 30 amp EVSE will draw about 27 amps, so I think I had better stay with a 20 amp EVSE, like the Clipper Creek.

Click to expand...

Good idea, unless you want to risk nuisance circuit breaker trips or worse, fire.

greengate said:

If I do this, I plan on running 10/2 from the junction box, taking one lead from the hot red wire and the other from the hot black wire, (about a 30 foot run, ) to the other side of the garage where I would run it into a 20 amp breakered disconnect switch. From this disconnect switch I would wire the Clipper Creek or install a dryer female outlet for the male plug on the Clipper Creek. (I am thinking about making it portable so I could take it to my sons where he would install a similar outlet off his air conditioner. (Wouldn't run them both at the same time.)

Click to expand...

That sounds like a hot mess.

greengate said:

Is it necessary to have a ground on the Clipper Creek? If so I could make the 30 foot run with 10/3, rather than 10/2 and pick up the ground from the neutral on the incoming 10/3.

Click to expand...

OMG, WTF? Are you trying to electrocute yourself or burn your garage down?

greengate said:

Your thoughts?

Click to expand...

Hire an electrician to install a proper sub-panel in your garage before you burn it down or electrocute someone.

If you insist on doing it yourself, give up on trying to hack it together.

Assuming that you actually have 10-3 running from your main panel to your garage and really want to avoid pulling a beefier run to the garage, I would do this:
1. Replace 2 15A single pole breakers with 30A dual pole breaker.
2. Install small sub panel in garage in place of junction box.
3. Feed your existing garage circuits with two new 15A single pole breakers.
4. Install new 20A circuit for EVSE (16A max to car) fed by dual-pole breaker in new sub-panel.

There will still be some risk of nuisance tripping with that setup. To be really safe you would have to limit your EVSE circuit to 15A (12A max to car).

drees said:

greengate said:

I realize a 30 amp ESEV would be pushing things, even if there were to be no additional draw coming from the 110 circuit A and circuit B, as the 30 amp EVSE will draw about 27 amps, so I think I had better stay with a 20 amp EVSE, like the Clipper Creek.

Click to expand...

Good idea, unless you want to risk nuisance circuit breaker trips or worse, fire.

greengate said:

If I do this, I plan on running 10/2 from the junction box, taking one lead from the hot red wire and the other from the hot black wire, (about a 30 foot run, ) to the other side of the garage where I would run it into a 20 amp breakered disconnect switch. From this disconnect switch I would wire the Clipper Creek or install a dryer female outlet for the male plug on the Clipper Creek. (I am thinking about making it portable so I could take it to my sons where he would install a similar outlet off his air conditioner. (Wouldn't run them both at the same time.)

Click to expand...

That sounds like a hot mess.

greengate said:

Is it necessary to have a ground on the Clipper Creek? If so I could make the 30 foot run with 10/3, rather than 10/2 and pick up the ground from the neutral on the incoming 10/3.

Click to expand...

OMG, WTF? Are you trying to electrocute yourself or burn your garage down?

greengate said:

Your thoughts?

Click to expand...

Hire an electrician to install a proper sub-panel in your garage before you burn it down or electrocute someone.

If you insist on doing it yourself, give up on trying to hack it together.

Assuming that you actually have 10-3 running from your main panel to your garage, I would do this:
1. Replace 2 15A single pole breakers with 30A dual pole breaker.
2. Install small sub panel in garage in place of junction box.
3. Feed your existing garage circuits with two new 15A single pole breakers.
4. Install new 20A circuit for EVSE (16A max to car) fed by dual-pole breaker in new sub-panel.

There will still be some risk of nuisance tripping with that setup. To be really safe you would have to limit your EVSE circuit to 15A (12A max to car).

Click to expand...

Great advice. Thanks. I will do that.

greengate said:

I have two 110 volt circuits in my garage that are fed by a 10/3 buried wire.

As it comes into the garage, it goes into a 4" junction box where from one side circuit A leaves and from the other side circuit B leaves.

Click to expand...

Since you mention buried wire, I am going to assume your garage is detached. If it is not, some of what follows does not apply.

For a detached garage, you need a disconnect nearest the point of entry of the conductors. For the case of a single multi-wire branch circuit as you have, that can be as simple as a double pole snap switch. So this 4" junction box should have a double pole snap switch in it.

greengate said:

Each circuit feeds separate things. On A are florescent lights, garage door opener, outside security light and two motion detector lights. Circuit B is for the charger that came with the Leaf. Both circuits share the common ground.

Click to expand...

All circuits share a common ground, I think what you mean to say is that the circuits share a common neutral, which is what makes it a multi-wire branch circuit.

greengate said:

In the 200 amp circuit breaker panel in the basement there are two separate breakers, each 15 amps and labeled as Circuit A and the other one as Circuit B. They could be pulling from the same side of the incoming 220. I'd have to change them anyway if I were to install an 220 volt EVSE in the garage by putting in a double breaker.

Click to expand...

Since you have a multi-wire branch circuit, the two breakers need to be on opposite legs of the panel. Otherwise, you could overload your neutral conductor. The two breakers should have a handle tie, so they need to be next to each other, which in most panels will arrange for them to be on opposite legs.

greengate said:

I realize a 30 amp ESEV would be pushing things, even if there were to be no additional draw coming from the 110 circuit A and circuit B, as the 30 amp EVSE will draw about 27 amps, so I think I had better stay with a 20 amp EVSE, like the Clipper Creek.

If I do this, I plan on running 10/2 from the junction box, taking one lead from the hot red wire and the other from the hot black wire, (about a 30 foot run, ) to the other side of the garage where I would run it into a 20 amp breakered disconnect switch.

Click to expand...

As soon as you add an EVSE to the picture you need to change the wire running to the garage from a branch circuit to a feeder, as you will need to use the full 30 amp capacity of the 10/3 buried wire and have additional circuit breakers in the garage, e.g. 20 amp breakers for the receptacles. So will you need to install a panel in the garage, and you will need to establish a grounding electrode system at the garage. The grounding electrode system could be as simple as two ground rods.

greengate said:

Is it necessary to have a ground on the Clipper Creek?

Click to expand...

Yes, in new work everything needs a ground. The EVSE, however, does not require a neutral.

Hiring an electrician to add a subpanel and a grounding electrode system is the way to go.

Cheers, Wayne

wwhitney said:

greengate said:

In the 200 amp circuit breaker panel in the basement there are two separate breakers, each 15 amps and labeled as Circuit A and the other one as Circuit B. They could be pulling from the same side of the incoming 220. I'd have to change them anyway if I were to install an 220 volt EVSE in the garage by putting in a double breaker.

Click to expand...

Since you have a multi-wire branch circuit, the two breakers need to be on opposite legs of the panel. Otherwise, you could overload your neutral conductor. The two breakers should have a handle tie, so they need to be next to each other, which in most panels will arrange for them to be on opposite legs.

Click to expand...

I love learning new stuff - Wayne, where does the requirement for a multi-wire branch circuit (shared neutral) to be protected by breakers with a handle tie come from? (and isn't that basically the same as a 2-pole breaker?)

drees said:

I love learning new stuff - Wayne, where does the requirement for a multi-wire branch circuit (shared neutral) to be protected by breakers with a handle tie come from? (and isn't that basically the same as a 2-pole breaker?)

Click to expand...

A double pole breaker has common trip and common disconnect. Two single pole breakers with a handle tie have common disconnect, but they may not have common trip. When one of the single pole breakers trips, the other may or may not be turned off by the handle tie.

For the NEC requirements, see 210.4 "Multiwire Branch Circuits".

Cheers, Wayne

wwhitney said:

drees said:

I love learning new stuff - Wayne, where does the requirement for a multi-wire branch circuit (shared neutral) to be protected by breakers with a handle tie come from? (and isn't that basically the same as a 2-pole breaker?)

Click to expand...

A double pole breaker has common trip and common disconnect. Two single pole breakers with a handle tie have common disconnect, but they may not have common trip. When one of the single pole breakers trips, the other may or may not be turned off by the handle tie.

For the NEC requirements, see 210.4 "Multiwire Branch Circuits".

Click to expand...

Duh, that makes sense. Unless you disconnect both hots, you may still end up with voltage/current on the shared neutral which will surprise you if you're ready for it!

OK, reviving an OLD thread is usually frowned upon, but I don't get to read here as much as I would like to, and I just wanted to say thank you to both drees and wwhitney for their helpful comments here and in a few other discussions too. I'm very interested in the correct wiring and also seeing/learning the technicalities of the NEC. What seems so simple to just run a wire or two is so much more complex, at least if you want to keep things safe.

On a side note, for my daughter's science project, we talked to an inspector here. He told us the story of a guy who replaced his water heater and rewired it incorrectly. It ended up that a vent or something was actually hot, and when a roofer worked on his house he was electrocuted. So it is a powerful reminder that safety is the highest priority.

I realize that the OP is just trying to save money by avoiding using a Licensed Electrician, but IMHO the risk to both your Leaf, People, and your Home far outweigh the cost of Hiring someone to install a proper circuit.

Also, IMHO having a smaller amp circuit installed because you can live with it now is also not a wise decision. Assume your next EV will be a Rav 4 EV or a Tesla and plan for it by having a larger amp circuit installed, up to 50 amps if your main breaker will allow for it. You will pay a little extra now, but will not have to re-do the install later.

Above all, think safety over saving money. Your life and the lives of your family are far more important.

Good luck.