Upgrade garage panel to 100amp for EV charger

Reply

  #1  
Old 07-17-19, 02:44 PM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
Upgrade garage panel to 100amp for EV charger

Main Panel 125amp Upgrade to 200amp in the future

30ft run from main panel to the garage panel

Two 1.25 (OD?) PVC conduits trough garage floor but only one currently continues underground to the main panel.
A conduit fill table I found says you can do 5 #2 wires in a 1.25 PVC SCH 40.
Will 2-2-2-4 copper be enough for 100amp?

If I need a 125-150amp panel will thicker #1 or #1/0 wire fit?
Can I run two of the wires in one 1.25 conduit and two in another?

Garage Panel Square D QO2-4L70F 70amp Max
Fed from double-pole 20 amp breaker in Main panel.
Replace with suitable 100amp+ panel. Would I need a 150amp panel if the EV charger can use up to 100amp with two cars and then two 20amp wall and light circuits?

Main Panel Siemens MC1224MB1100S Series B Type 3R 125amp Max

Replace double-pole 20 amp breaker with double-pole 100amp+ breaker.

 
Attached Images     
Sponsored Links
  #2  
Old 07-17-19, 03:36 PM
Member
Join Date: Feb 2016
Location: United States, Virginia
Posts: 1,132
Upvotes: 0
Received 19 Votes on 16 Posts
For 100A you can use #3Cu, so the feeder can be four conductors in the sizes of 3-3-3-6. 1.25" conduit is the inside diameter. You are not to split the circuit between two conduits.
 
  #3  
Old 07-17-19, 04:53 PM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
Sure wish I’d know I would have an electric car when I built the garage.

So I have two 1” ID PVC conduits and the max I can do is 100amp on a 3-3-3-6 cable in one conduit. Even if I could cram 2-2-2-4 in there that just gets me from 100 to 115amps?

“You are not to split the circuit between two conduits.”

But they are right next to each other. The conduits would be touching side by side for 90% of the run.


Just had an electrician come out and he said that he could get 100amp wire (don’t know what size) through but that he would use single wires and not a cable.

He also said that splitting the circuit run is not to code but not likely to hurt anything. Also thought that running ground through the second conduit would be ok but it would not give you enough space to make a difference.

If both panels are grounded why ground the panels together?
 
  #4  
Old 07-17-19, 06:17 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,812
Received 33 Votes on 29 Posts
What is the circuit required for the charger? I would be willing to bet you do not need 100 amps to the garage just because of the charger, especially since the charger will likely be run at night.

All circuit conductors are required to be run together in the same pipe, except the ground can be separate. It doesn't matter if they are next to each other or not, running them separately will cause inductance issues.

If both panels are grounded why ground the panels together?
A ground path must be installed in every circuit and anything that might become energized is required to be bonded together to the ground wire.
 
  #5  
Old 07-17-19, 10:12 PM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
Yeah it's highly unlikely that I'd be running the charger along with anything else but I guess it's possible during the middle of the day on the weekend to want to charge. I thought you just needed to make the circuit breaker be able to cover the possible max. A single car charging only requires around 60 amps but you can add a second one and together they max out at 100 amps plus there are lights and outlets that I again would be unlikely to be using at the same time but still. If everything was somehow on at the same time I'd need 140 amps or so and then are you not required to have a little more than your theoretical Max use?

So would you have 100 amp breaker at the main and then the sub would also have 100 amp breaker for the charger and two 20 amp breakers for the lights and outlets and then the hundred amp breaker at the main wood trip if somehow they were all on at the same time? Or would code require that the breaker at the main panel be able support the maximum at the subpanel?
 
  #6  
Old 07-18-19, 05:26 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,922
Upvotes: 0
Received 37 Votes on 35 Posts
The feeder breaker in the main panel has to be sized for the smallest of: the incoming service, the outgoing feeder wire gauge, the subpanel max ampacity. The limiting factor is usually the outgoing feeder wire gauge. Your subpanel does not need to be sized for the theoretical max, but for actual expected load. Add 20% on top of that if the expected load is "continuous", which means runs for more than 3 hours non-stop per the code definition. You may also want to dig into the electrical specs on the car charger, because the manufacturer may have already baked in the 20%.
 
  #7  
Old 07-20-19, 05:05 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,812
Received 33 Votes on 29 Posts
I would recommend installing whatever wires you can legally install in the conduits you have available. According to my calculations, you can get 3 #3 THHN/THWN and one #8 in a 1" PVC conduit. This will get you the full 100 amps to the garage.

If you want to skinny up a little you can install 3 #4 and one #8. That will get you 90 amps.
 
  #8  
Old 07-20-19, 06:06 AM
Member
Join Date: Feb 2016
Location: United States, Virginia
Posts: 1,132
Upvotes: 0
Received 19 Votes on 16 Posts
I agree with Tolyn. When I said down in post #2 the ground being #6, I should have said #8 for 100A.
 
  #9  
Old 07-30-19, 09:20 AM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
I got a quote for $2880! and they say the conduit would be 80amps max.

"Existing Romex is not protected under 8'. This quote assumes owner will protect existing and new Romex."
 
  #10  
Old 07-30-19, 04:24 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,911
Received 17 Votes on 12 Posts
Get another quote. ..............
 
  #11  
Old 07-31-19, 01:48 PM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
Working on it but that seemed really high and I don't know what the protect Romex is about.
 
  #12  
Old 07-31-19, 01:59 PM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,922
Upvotes: 0
Received 37 Votes on 35 Posts
Yes it does seem high, but prices vary a lot by area for a variety of reasons.

Modern code requires romex to be protected from damage in garages, whereas it used to be left exposed like yours is. Providing protection would mean adding some protective covering over areas where there is exposed cable (boards, paneling, sheetrock, etc). Moving some runs to conduit might be required. This contractor may be anticipating a requirement from the local inspector.
 
  #13  
Old 08-07-19, 12:35 PM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
Will this panel work? Anything to look out for?

https://www.schneider-electric.us/en...0a-1ph-6sp-n1/
 
  #14  
Old 08-07-19, 02:03 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,812
Received 33 Votes on 29 Posts
Yes, that will work. However, I like to use the same brand panels that the main service is. That way if I ever need to replace a breaker I know what kind I need. ( It looks like your main panel is a Siemens/ITE.
 
  #15  
Old 08-07-19, 07:04 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,911
Received 17 Votes on 12 Posts
It also looks like the Siemens/ITE panel has a few 2-pole breakers in it that should be in it. It looks to me like some Bryant and maybe a Cutler-Hammer BR breaker has been used. Those should be replaced with Siemens breakers.
 
  #16  
Old 08-09-19, 01:58 PM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
I was mostly looking for something that can fit in that odd wall space. It’s less than 10” across I think.

The plan is to replace the main panel soon as well. I normally like to make stuff match but the odds of ever touching the stuff again are so slim. I did not install any of them, the house came that way and it's been 30 years.

See lots of back and forth about mixing brands but some say they are standard for a reason and just because they are not UL-ed in that panel it’s silly to think that they will not function. If they fit and you did not use a hammer and they don’t push against the other breakers and look exactly the same, have the same specs and everything in the panel is nice and cool under load and some are not bolted vs. clamped and so on, why not? It’s possible there could be an unseen issue but not one above normal failure rates? If it is so dangerous why not key them by size or shape? I’m sure manufactures would love to give away panels if you could only physically fit their breakers in them. Unfortunately these days you are in much more danger from recalled or poorly designed breaks or panels.

Could not find anything about breakers or panels let alone mixing brands, just recalled makes and models.

Top 10 house fire causes :
1. Cooking equipment
2. Heating
3. Smoking in bedrooms
4. Electrical equipment
5. Candles
6. Curious children
7. Faulty wiring
8. Barbeques
9. Flammable liquids
10. Lighting
 
  #17  
Old 08-09-19, 06:30 PM
Member
Thread Starter
Join Date: Jul 2019
Location: United States
Posts: 16
Received 0 Votes on 0 Posts
From the panel to the other side of the garage I was just planning on running a cable capable of 100 amps should that be in conduit as well if I go up and over and then down to the charger on the other side? The garage has no sheetrock or ceiling so it would be exposed to open air.
 
  #18  
Old 08-10-19, 05:45 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,812
Received 33 Votes on 29 Posts
#7 would cover using incorrect breakers in a panel. The breakers are not listed for use in your panel.

A cable installed inside a building will need to be protected. This is normally done by running the cable inside the framing wall cavities or in attic spaces. If this can't be done then it should be run in conduit for protection. This also falls under the note "Existing Romex is not protected under 8'. This quote assumes owner will protect existing and new Romex." that was on the quote you received. Cable (Romex) needs to be protected.

If you are running outside/underground you will need to use a cable rated for a wet location, like UF. Standard NM-b is not allowed in a wet location and conduit outside is a wet location.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes