potential house charging possibilities

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#1
Looking at buying a house, and trying to have an electrician come out and inspect how much would need to be done to install charging before we close contingencies.

Anyone here have insight into the current state of electrical?

100amp service, and subpanel in the garage

I've attached photos of the main panel and subpanel, and just don't have any experience with what's going on haha

any thoughts are appreciated, and I realize that I need to have it looked at in person by a professional

screen-shot-2018-03-14-at-8-45-59-am-png.6317
screen-shot-2018-03-14-at-8-45-42-am-png.6318
 

ng0

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#2
I'm not electrician (far from it) but judging by your pictures, it seems like that whole thing needs to be replaced. I have an old 1950s house and the first thing I did was have an electrician replace the panel and rewire the house. It wasn't cheap, but well worth it.
 

garsh

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#3
I'm not electrician (far from it) but judging by your pictures, it seems like that whole thing needs to be replaced.
Agree. A Tesla Wall Connector can be connected up to a 100 amp circuit of its own. A 240v outlet appropriate for a mobile connector will usually be connected to a 50 amp circuit. Modern houses have at least a 200 amp service. Given that electric cars are going to take over in the next 10-20 years, I would recommend 250-300 amp service nowadays, if possible.
 

Jan King

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#4
Looking at buying a house, and trying to have an electrician come out and inspect how much would need to be done to install charging before we close contingencies.

Anyone here have insight into the current state of electrical?

100amp service, and subpanel in the garage

I've attached photos of the main panel and subpanel, and just don't have any experience with what's going on haha

any thoughts are appreciated, and I realize that I need to have it looked at in person by a professional

View attachment 6317 View attachment 6318
The model 3 long range can charge with 48 Amps. This requires a 60 Amp breaker (in our area). You do not need to charge with the full 48 Amps, you can use whatever amps are available to you buy buying either the HPWC gen 2 where you can dial down the amps to what you have or use the 14-50 outlet and tell the car to take less amps.
 

eprosenx

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#5
Looking at buying a house, and trying to have an electrician come out and inspect how much would need to be done to install charging before we close contingencies.

Anyone here have insight into the current state of electrical?

100amp service, and subpanel in the garage

I've attached photos of the main panel and subpanel, and just don't have any experience with what's going on haha

any thoughts are appreciated, and I realize that I need to have it looked at in person by a professional

View attachment 6317 View attachment 6318
So actually, I don't see anything too horrible or scary here. While this looks messy, I don't see any obvious code violations or safety hazards. Depending on the situation you might be able to add a charging circuit that would be sufficient for your needs (though probably not a full 50a circuit).

First off: Can you post higher resolution pictures so we can see the amperage of all the breakers and read the writing on them as much as possible? I don't recognize that model of panel so I want to research it. Please also take a picture of the "panel schedule" with all the breaker labels. Additionally, there is usually a sticker on the door or something with all the gory details of instructions of how to wire the panel, what model of breakers are acceptable, etc...

Some notes from what I see:
  • I can't tell if that subpanel in the garage is a single phase (or phase leg as it were) or a dual phase panel. More pictures would be useful (specifically of the two main lugs, the instruction sticker, etc...). Regardless, I suspect that subpanel is tapped out and so you will have to run a new wire from the main panel for pretty much anything you do. Though actually, what does the subpanel feed btw? Looks like three circuits.
  • You have four 20a single phase breakers I think that might be candidates to be "doubled up" onto the higher density breakers, which would give you space to install a dual pole 240v breaker for an EV charger.
  • What is the 40a circuit for? Since this appears to be your only 240v load, you might be able to get away with adding an EV charger load calculation wise. You will need to run a load calculation on the house (there is a formula) to see where you are load wise according to the NEC.
  • If you do put in double density breakers, do be careful to make sure any multi-wire branch circuits (shared neutral) are on opposite phase legs so that they don't overload the neutral. (I see lots of red wires in addition to the black ones which typically is one indication of this). They are totally safe as long as you follow this precaution.
How many miles do you typically drive in a day? Many people can get away with less than 48 amps charging capacity if their driving demands don't require it, but YMMV (literally). I personally would never want a house with less than a 200a service (my new one will be 320/400 amps), but that is just me!
 
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#6
thanks for the info

well I ended up getting service upgraded to 200A while having solar installed, which is working out well so far

the garage subpanel is now 115A panel on a 100A breaker, and got the HPWC on a 100A breaker in that panel. I just wanted a 60A breaker to max out model3, but the charger is right next to the garage subpanel and he had leftover wire from new conduit from main panel to garage subpanel, so, ready for a Model S or X I suppose :p
 

eprosenx

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#7
thanks for the info

well I ended up getting service upgraded to 200A while having solar installed, which is working out well so far

the garage subpanel is now 115A panel on a 100A breaker, and got the HPWC on a 100A breaker in that panel. I just wanted a 60A breaker to max out model3, but the charger is right next to the garage subpanel and he had leftover wire from new conduit from main panel to garage subpanel, so, ready for a Model S or X I suppose :p
Nice! Though I am not sure about doing a 100a service to the Wall Connector off a 100a fed subpanel that also has other circuits on it. Load calcs wise, if the Wall Connector were to be used to the max of 80 amps continuous (which requires reserving another 25% capacity), that would leave no overhead on the feeder for other loads.

So I think the 100a breaker and feed wire to the HPWC is cool and a good idea, but you may need to think about setting the HPWC down a little max current wise (rotary dial inside cover) in order to not create an issue in the future when perhaps someone might buy a Tesla that could draw the full 80 amps and then that in combination with your other garage loads could create an issue.
 

PNWmisty

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#8
thanks for the info

well I ended up getting service upgraded to 200A while having solar installed, which is working out well so far

the garage subpanel is now 115A panel on a 100A breaker, and got the HPWC on a 100A breaker in that panel. I just wanted a 60A breaker to max out model3, but the charger is right next to the garage subpanel and he had leftover wire from new conduit from main panel to garage subpanel, so, ready for a Model S or X I suppose :p
If it's on a 100 amp breaker, the sub-panel is a 100 amp sub-panel.
 
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#9
If it's on a 100 amp breaker, the sub-panel is a 100 amp sub-panel.
I believe installer said it's 125A (not sure why I had 115 in my head) rated subpanel, not completely sure though.

It's backfed with solar panels on garage in addition to fed from main panel on house
 

eprosenx

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#10
I believe installer said it's 125A (not sure why I had 115 in my head) rated subpanel, not completely sure though.

It's backfed with solar panels on garage in addition to fed from main panel on house
Yeah, 125a is a common rating for some panel boards. But if it is fed from a 100a breaker (and appropriate ampacity wire) then it is only a 100a panel even though the bus can handle more.

I question whether it is allowed to backfeed from a subpanel? This seems questionable to me (though I don't know where in the NEC to point you to say it is not allowed).

I also don't think the load calcs work out to have a 100a Tesla charger plus three other circuits on that subpanel that is only fed from 100a. Setting the Tesla charger down to a lower max amperage will solve the issue though.
 

Professor

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#11
Hey there,

I have a 220 volt electric dryer receptacle about 12" from my garage firewall, inside the laundry room.

Should I have an electrician extend the receptacle, in a conduit, through the firewall and about 15' into the garage for an optimal location to plug in my Tesla3, or is there a way to plug in the Tesla charger in the laundry room and extend it into the garage, through a UL listed firestop sleeve and then 15' into the garage. Any ideas?
 

iChris93

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#12
  • If you do put in double density breakers, do be careful to make sure any multi-wire branch circuits (shared neutral) are on opposite phase legs so that they don't overload the neutral. (I see lots of red wires in addition to the black ones which typically is one indication of this). They are totally safe as long as you follow this precaution.
I don’t want to hijack this thread, but could you please explain this more? It is not clear to me.
 

slacker775

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#13
Hey there,

I have a 220 volt electric dryer receptacle about 12" from my garage firewall, inside the laundry room.

Should I have an electrician extend the receptacle, in a conduit, through the firewall and about 15' into the garage for an optimal location to plug in my Tesla3, or is there a way to plug in the Tesla charger in the laundry room and extend it into the garage, through a UL listed firestop sleeve and then 15' into the garage. Any ideas?
I take it you still need to use that outlet for the dryer as well? If so, check out Dryer Buddy which lets you ‘share’ the outlet. If the dryer isn’t running, your EV can charge. If the dryer gets used, it stops ‘disables’ the EV outlet so it stops charging. No thrown breakers, no need for a dedicated circuit. Of course, if you are drying clothes 24x7, maybe not a good option but certainly cheaper than running a new outlet.
 

Professor

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#14
Hey there,

I have a 220 volt electric dryer receptacle about 12" from my garage firewall, inside the laundry room.

Should I have an electrician extend the receptacle, in a conduit, through the firewall and about 15' into the garage for an optimal location to plug in my Tesla3, or is there a way to plug in the Tesla charger in the laundry room and extend it into the garage, through a UL listed firestop sleeve and then 15' into the garage. Any ideas?

In a nutshell, can I plug a Tesla charger into the 220 volt electric clothes dryer outlet, or should I have an electrician extend the existing outlet into the garage? I have a gas clothes dryer.
 

slacker775

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In a nutshell, can I plug a Tesla charger into the 220 volt electric clothes dryer outlet, or should I have an electrician extend the existing outlet into the garage? I have a gas clothes dryer.
The Tesla MWC chafer that comes with the car can be plugged into the dryer outlet, though you will probably need to get an outlet adapter for $35. You’ll most likely be at 30A which gets you about 22mph charging. Definitely cheaper than getting an electrician out and a perfectly legit charging scenario.
 

slacker775

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#16
Ahh, I’m seeing that the dryer outlet is close, but not in the garage. The best bet is probably to have an electrician (re)route it into the garage to an outlet in a convenient location within the garage.
 

Professor

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#17
Ahh, I’m seeing that the dryer outlet is close, but not in the garage. The best bet is probably to have an electrician (re)route it into the garage to an outlet in a convenient location within the garage.
Sounds good to me. I hate to have the garage door ajar for the power cord when charging, especially at night.

Thank-you for your good advice!
 

eprosenx

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#18
Sounds good to me. I hate to have the garage door ajar for the power cord when charging, especially at night.

Thank-you for your good advice!
From what you have described here:

1. I would not route it through the door and leave the door open. Lots of reasons not to do this (heating/cooling, fire danger, rodents, etc...)
2. An electrician may be able to move this outlet for you since you have a gas dryer and don't need it, but I would just more look into running a new dedicated circuit. Depending on where your electrical box is this may be cheaper and easier and just better all around. You may also get faster charging this way (all depending on what available capacity remains with your electrical service).

Depending on your plans / setup I would consider installing a wall connector over just using the UMC. I personally always want my UMC in the car "just in case" and I don't want to have to plug it in every day (so that means I needed a second UMC or instead I just bought a wall charger).
 

eprosenx

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#19
I don’t want to hijack this thread, but could you please explain this more? It is not clear to me.
Great question!

So in the US residences generally have "single phase power". Though it is delivered as "split phase" which means that you get basically three wires from the utility. One which is connected to one end of the secondary winding of the transformer and another that is connected to the other end of the secondary winding on the transformer. These are both referred to as "hots". Voltage from hot to hot is 240v nominally. Then the third one (neutral) is "center tapped" on that same transformer winding. This one is also bonded to ground for safety reasons. Voltage from either hot to neutral is 120v nominally.

Basically with this setup the two "hot's" are 180 degrees out of phase from each other. So you can hook up two say 20a circuits, one hooked to hot "A" and one hooked to hot "B" and with a shared neutral wire. Because of the fact that the two hots are 180 degrees out of phase from each other, if you load both circuits to five amps then the net loading on the neutral is zero. If you load one circuit five amps and the other to ten amps the net loading is five amps on the neutral.

So it allows an optimization on wire costs for the neutral. (three phase commercial systems allow three circuits to share one neutral in a similar way)

The important bit that I described is that you need to make sure that if you are moving around circuits in your breaker panel (such as when doubling up circuits onto breakers) you need to ensure that any two circuits sharing a neutral are on opposite phases, otherwise you could overload the neutral (i.e. if both circuits are on the same phase then in the case where both circuits are drawing five amps then the load on the neutral is ten, not zero).

Does that make sense?
 

iChris93

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#20
Great question!

So in the US residences generally have "single phase power". Though it is delivered as "split phase" which means that you get basically three wires from the utility. One which is connected to one end of the secondary winding of the transformer and another that is connected to the other end of the secondary winding on the transformer. These are both referred to as "hots". Voltage from hot to hot is 240v nominally. Then the third one (neutral) is "center tapped" on that same transformer winding. This one is also bonded to ground for safety reasons. Voltage from either hot to neutral is 120v nominally.

Basically with this setup the two "hot's" are 180 degrees out of phase from each other. So you can hook up two say 20a circuits, one hooked to hot "A" and one hooked to hot "B" and with a shared neutral wire. Because of the fact that the two hots are 180 degrees out of phase from each other, if you load both circuits to five amps then the net loading on the neutral is zero. If you load one circuit five amps and the other to ten amps the net loading is five amps on the neutral.

So it allows an optimization on wire costs for the neutral. (three phase commercial systems allow three circuits to share one neutral in a similar way)

The important bit that I described is that you need to make sure that if you are moving around circuits in your breaker panel (such as when doubling up circuits onto breakers) you need to ensure that any two circuits sharing a neutral are on opposite phases, otherwise you could overload the neutral (i.e. if both circuits are on the same phase then in the case where both circuits are drawing five amps then the load on the neutral is ten, not zero).

Does that make sense?
Ah, yes! I’m an electrical engineer so I’ve learned and knew about center tapped transformers but it didn’t click about current cancellation from the two different live wires. Thanks!