Run a 60 amp circuit or 90 amp subpanel

[pr3dict]

Getting my first EV and need to install a 50 amp charger in the (attached) garage. I currently have a 200 amp 42 space main panel and a 6 space subpanel in my basement that are full.

To add a 2 space 60 amp circuit I'd have to replace the existing subpanel in the basement for a larger one. And then run a 6ga romex to the garage @ a little over $3/foot.

The other option is after substituting the 6 space sub panel for a larger one, I then take that 6 space and install it in the garage w/ 2AL SER cable.

The 2AL SER cable is like $2/foot.

Im not sure which would be easier to pull/bend 2AL or 6ga copper. Any thoughts? Also adding a 90 amp sub panel isnt really going to get me much. I was just thinking about it because I'll have the extra panel at that point but considering the EV charger is a 60amp breaker not much I'm going to be able to add in the future to a 90 amp sub panel.

Also I have a detached garage with 100amp service for my workshop etc.

Thoughts?

 

[u3b3rg33k]

if you have to pull big wire, I'll always vote for the subpanel. QO goes up to 125A breakers, and for the 15/20A breakers, you may land 2 wires per breaker FYI.

 

[alfredeneuman]

If you ran the circuit (or possibly subpanel) directly from the main panel it would eliminate all the hassle in the basement.

 

[pr3dict]

If you ran the circuit (or possibly subpanel) directly from the main panel it would eliminate all the hassle in the basement.

I worded that weirdly. The 200amp main and 100amp sub are right next to each other in my basement. Both are full.

 

[sparky 1971]

#2 SER cable isn't bad at all. It's obviously larger than 6/3 but it's lighter and bends easier. Since it costs less and you already are planning on swapping out the existing subpanel, go that route. You can put the EV charger right under the sub, then go to Home Depot and have them cut #8 THHN/THWN to the length you need for that receptacle.

 

[alfredeneuman]

Both are full

Do you know if the main panel will accept tandem breakers?

 

[pr3dict]

Do you know if the main panel will accept tandem breakers?

It will accept them physically but its a QO breaker panel - The 42 space+ units do not allow double circuits aka tandem breakers. I thought about that though...

 

[AZ Garage]

You need to do a whole house load calculation before you do anything.

 

[pr3dict]

You need to do a whole house load calculation before you do anything.

Lol what's that going to help with? The highest I can go is the 200 amp service I have

 

[Innovate1]

I say put a bigger subpanel in the basement and move the existing to the garage. It gives you a few empty spaces each place for future stuff. I would run the garage subpanel directly from the main panel.

 

[Noltz]

Have you considered using Tandem breakers to free up 2 spots in your main panel? I did this and installed 4 tandems to free up 4 spots (in my case it was two 240v breakers - EV and Generator Interlock). Then just run 6ga Romex out to the EV port.

 

[pr3dict]

Have you considered using Tandem breakers to free up 2 spots in your main panel? I did this and installed 4 tandems to free up 4 spots (in my case it was two 240v breakers - EV and Generator Interlock). Then just run 6ga Romex out to the EV port.

I physically can do that but code wise this panel does not allow tandem breakers.

 

[woodscaper]

Where are you getting 6-3 with ground for 3 bucks a foot? Around here it's almost 7 bucks a foot!

 

[pr3dict]

Where are you getting 6-3 with ground for 3 bucks a foot? Around here it's almost 7 bucks a foot!

6/2 not 6/3. It's 240 with no neutral

 

[sparky 1971]

I physically can do that but code wise this panel does not allow tandem breakers.

What about the sub? If the sub is 100 amp, I wouldn't have a problem running the charger off of it. You could also move two circuits from the main to the sub by using twins. I also wouldn't have a problem using twins on my own house panel even if it isn't listed for them. At one time I had 42 circuits in my 30 space 100 amp panel. After many years, I put in a 200 amp service and finally took care of it. It's now a 100 amp sub fed from a 100 amp breaker using #2 SER, but it only has 29 circuits in it.

 

[nadogail]

I say put a bigger subpanel in the basement and move the existing to the garage. It gives you a few empty spaces each place for future stuff. I would run the garage subpanel directly from the main panel.

Room for future expansion is always a plus.

 

[pr3dict]

What about the sub? If the sub is 100 amp, I wouldn't have a problem running the charger off of it. You could also move two circuits from the main to the sub by using twins. I also wouldn't have a problem using twins on my own house panel even if it isn't listed for them. At one time I had 42 circuits in my 30 space 100 amp panel. After many years, I put in a 200 amp service and finally took care of it. It's now a 100 amp sub fed from a 100 amp breaker using #2 SER, but it only has 29 circuits in it.

Currently the 100amp has a 50 amp for the hot tub, 40amp for the hot water heater, 20 for microwave and 20 for something else...

So I definitely can't put the charger also because there is a good chance the charger and one of those other big load devices will be on at the same time.

Probably going to end up running another sub.

 

[woodscaper]

6/2 not 6/3. It's 240 with no neutral

If you put a sub in you need a neutral

 

[pr3dict]

If you put a sub in you need a neutral

I get that... The question is the difference between 6/2Cu @ $3/sqft for a 60 amp circuit vs 2AL SER (4 wire) @ $2/sqft for a 90 amp sub panel.

It would be roughly the same amount of money becuase I'd need to buy a 90 amp breaker, a 60 amp breaker, and the wire would be a wash... Some people say 2AL even 4 wire is easier to pull then 6/2Cu. Would also give me future expansion.

The sub panel I have doesnt have a cover over the breakers though... Hmmm I wonder if that'll be an issue.

 

[sparky 1971]

Currently the 100amp has a 50 amp for the hot tub, 40amp for the hot water heater, 20 for microwave and 20 for something else...

So I definitely can't put the charger also because there is a good chance the charger and one of those other big load devices will be on at the same time.

Probably going to end up running another sub.

You can do it however you want, and I think that adding a sub in the garage is going to be the best route. But, don't get too hung up on the amperage of the breakers in your existing sub panel. 100 amps is a lot of power. In my above scenario of my own house 42 circuits in a 30 space panel there was an electric range, electric dryer. electric water heater, AC and (38) 120 volt circuits, but a lot of those 120 circuits were one receptacle circuits I added here and there over the years just because it was easier to go back to the panel rather than pick it up off of something elsle That 100 amp service was on a rural pole and not only took care of the house, but there was another overhead line that went to my shop. In the summertime, on the weekends, it was entirely possible for all the 240 appliances in the house to be running at the same time if the wife was baking while I could be out tinkering in the shop and have the air compressor or welder going along with whatever else I had going on at the same time. Table saw, miter saw, etc.

As far as the coverless panel, just buy another panel. They are cheap enough. You might be able to buy a cover, but it will probably cost as much or more than the whole thing.

 

[pr3dict]

An update to this. I added a 90A sub off the main w/ the SER cable then hardwired the 60A EV charger to the sub in the garage... That way if I ever add a second EV I can run a 2nd charger off it and just lower the amperage of each to ~40A or so.

 

[wyliesdiesels]

If you put a sub in you need a neutral

based on what code? if he only runs 240v equipment off of it, no neutral is needed or required