LeftieBiker
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Re: Idea for apartment dwellers: 'host' charging through window

Wed Feb 06, 2019 2:11 pm

The spring-loaded 'backstab' outlets are the dangerous ones. Leviton, IIRC, makes rear-connect outlets in which the internal clamps are tightened and held by the side screws instead of by a spring. So those are about as safe as the side connect outlets.
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Oilpan4
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Re: Idea for apartment dwellers: 'host' charging through window

Thu Feb 07, 2019 2:36 am

I think we can all agree, don't use the cheapest receptacles you can find for your evse circuit.
2011 white SL leaf with 2014 batt.
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Quothmar
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Re: Idea for apartment dwellers: 'host' charging through window

Fri Feb 08, 2019 5:04 am

Oilpan4 wrote:Virtually no one wires up room outlets for continuous high amp use.
Oh and if some amateur wired the receptacles with the "back stab" method there will be a fire.
I just read about 'backstabbed' outlets, and they sound dangerous. But will there be a fire?

Much of these discussions surround the notion of what makes a wise decision, given that opposing decisions have alternate risks. In an earlier post, you gave some figures involving the risk that blown-in cellulose insulation would create a fire hazard: that 16 amps on 14-gauge wire running continuously could push the cellulose toward its temp rating of 60 degrees Celsius.

How do you arrive at these figures? Have you actually done thermal calculations with the physical properties of cellulose to determine the probability of a fire? I only took a few basic physics courses, but I would be interested to further research your claims.

The only reference I found to the temp ratings of various types of insulation are here:

https://www.engineeringtoolbox.com/insu ... d_922.html
https://en.wikipedia.org/wiki/Insulatio ... IEC60085-3

None of the ratings shown go as low as 60 degrees Celsius. I'm also reading that cellulose is treated with fire-retardant material, making it safer for use around electrical wires.

Somehow, I think you would have to arrive through thermal calculations at the probability of a fire, and incorporate that probability into a further calculation involving the probabilities of other expected outcomes and their relative magnitudes of favorability (air pollution, ozone damage). While favorability isn't as easily measured as the likelihood of a fire or of health hazards due to air pollution, I think some kind of cost-benefit analysis would have to weigh in before we could automatically dismiss home-charging on a room circuit as unwise.

Again, this is for one car. I did some research and found that the upper wattage limit for a 12-volt, 14-gauge wire is 2400 watts, which is well above the 1300 used by my EVSE. Although two cars charging at once would not work (1300 + 1300 = 2600 > 2400), I still like my idea of putting each charge port on a timer (say, 7:00 PM - 11:00 PM, 11:00 PM - 3:00 AM, 3:00 AM - 7:00 AM), to ensure that 1300 watts is never exceeded.

As a competitor to the idea of host charging, however, see below...
WetEV wrote:
Quothmar wrote:If not by host charging, how would you say that we should get apartment complexes to make it practical for residents to own electric vehicles?
Installing EVSEs in the parking areas for residents only. L2 240V/208V, hourly limit, dual cord units would probably be best. One for every N units, with N being perhaps 5, more or less. 4 hour limit during the day, perhaps 8 hours or a bit more overnight.

Or in more expensive apartments, for a unit only, perhaps in a garage, perhaps with a separate rental agreement.

And/or charging at work.

A problem that will need to be solved once the percentage of EVs gets up to near 50%.
At first, I was skeptical that EVs could ever get up to 50% without allowing apartment-dwellers to charge their EVs at home. Oddly enough, I never bothered to do the research to see that roughly 3/4 of the United States population live in houses. I imagined that apartments were more 'compact' and that there would be more people living in them. But if more people live in houses, then putting more responsibility on house-owners to purchase electric vehicles, until EV-driving house-owners reach a certain percentage of the population, and then mandating that charging stations be installed at apartment complexes, could work.

So host charging would not be necessary to get the ball rolling for apartment complexes, though it may nevertheless be a viable supplementary strategy.

LeftieBiker
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Re: Idea for apartment dwellers: 'host' charging through window

Fri Feb 08, 2019 5:57 am

Few household wiring fires start inside the cables themselves. Instead, they usually start at the connections: connections at the outlet and inside the outlet, connections at the main service panel (rare) and connections at junction boxes in between. Junction and outlet and switch boxes were originally fire-suppression devices: by confining a connection fire inside a sealed steel box, the fire was smothered by exhausting the oxygen. Now, with plastic boxes in use, you'd better hope that fire gets smothered VERY quickly...
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

Oilpan4
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Re: Idea for apartment dwellers: 'host' charging through window

Fri Feb 08, 2019 6:21 am

Quothmar wrote:
Oilpan4 wrote:Virtually no one wires up room outlets for continuous high amp use.
Oh and if some amateur wired the receptacles with the "back stab" method there will be a fire.
I just read about 'backstabbed' outlets, and they sound dangerous. But will there be a fire?

Much of these discussions surround the notion of what makes a wise decision, given that opposing decisions have alternate risks. In an earlier post, you gave some figures involving the risk that blown-in cellulose insulation would create a fire hazard: that 16 amps on 14-gauge wire running continuously could push the cellulose toward its temp rating of 60 degrees Celsius.

How do you arrive at these figures? Have you actually done thermal calculations with the physical properties of cellulose to determine the probability of a fire? I only took a few basic physics courses, but I would be interested to further research your claims.

The only reference I found to the temp ratings of various types of insulation are here:

https://www.engineeringtoolbox.com/insu ... d_922.html
https://en.wikipedia.org/wiki/Insulatio ... IEC60085-3

None of the ratings shown go as low as 60 degrees Celsius. I'm also reading that cellulose is treated with fire-retardant material, making it safer for use around electrical wires.

Somehow, I think you would have to arrive through thermal calculations at the probability of a fire, and incorporate that probability into a further calculation involving the probabilities of other expected outcomes and their relative magnitudes of favorability (air pollution, ozone damage). While favorability isn't as easily measured as the likelihood of a fire or of health hazards due to air pollution, I think some kind of cost-benefit analysis would have to weigh in before we could automatically dismiss home-charging on a room circuit as unwise.

Again, this is for one car. I did some research and found that the upper wattage limit for a 12-volt, 14-gauge wire is 2400 watts, which is well above the 1300 used by my EVSE. Although two cars charging at once would not work (1300 + 1300 = 2600 > 2400), I still like my idea of putting each charge port on a timer (say, 7:00 PM - 11:00 PM, 11:00 PM - 3:00 AM, 3:00 AM - 7:00 AM), to ensure that 1300 watts is never exceeded.

As a competitor to the idea of host charging, however, see below...
WetEV wrote:
Quothmar wrote:If not by host charging, how would you say that we should get apartment complexes to make it practical for residents to own electric vehicles?
Installing EVSEs in the parking areas for residents only. L2 240V/208V, hourly limit, dual cord units would probably be best. One for every N units, with N being perhaps 5, more or less. 4 hour limit during the day, perhaps 8 hours or a bit more overnight.

Or in more expensive apartments, for a unit only, perhaps in a garage, perhaps with a separate rental agreement.

And/or charging at work.

A problem that will need to be solved once the percentage of EVs gets up to near 50%.
At first, I was skeptical that EVs could ever get up to 50% without allowing apartment-dwellers to charge their EVs at home. Oddly enough, I never bothered to do the research to see that roughly 3/4 of the United States population live in houses. I imagined that apartments were more 'compact' and that there would be more people living in them. But if more people live in houses, then putting more responsibility on house-owners to purchase electric vehicles, until EV-driving house-owners reach a certain percentage of the population, and then mandating that charging stations be installed at apartment complexes, could work.

So host charging would not be necessary to get the ball rolling for apartment complexes, though it may nevertheless be a viable supplementary strategy.
NEC 625.29 states the evse shall be plugged into the receptacle and not be plugged into an extension cord.

NEC 210.17 states that a receptacle used for charging an electric vehicle shall not contain other receptacles. Each electric vehicle charger is to be on its own dedicated circuit.

NEC 240.4 requires a 15 amp breaker on a 14 gauge circuit.

If you plug a 16 amp load on a 15 amp breaker it may trip after 2 or 3 hours.

So the NEC answer to can I plug an extension cord into some random apartment receptacle that may be on a 15 circuit to charge an EV is no, no and no. Or just no and no.

Ignore NEC, test your smoke detectors for real and meet the fire department.

Any other questions?
Last edited by Oilpan4 on Fri Feb 08, 2019 6:53 am, edited 3 times in total.
2011 white SL leaf with 2014 batt.
Chargers: Panasonic brick moded for 240v, duosida 16a 240v and a 10kw setec portable CHAdeMO
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Oilpan4
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Re: Idea for apartment dwellers: 'host' charging through window

Fri Feb 08, 2019 6:45 am

LeftieBiker wrote:Few household wiring fires start inside the cables themselves. Instead, they usually start at the connections: connections at the outlet and inside the outlet, connections at the main service panel (rare) and connections at junction boxes in between. Junction and outlet and switch boxes were originally fire-suppression devices: by confining a connection fire inside a sealed steel box, the fire was smothered by exhausting the oxygen. Now, with plastic boxes in use, you'd better hope that fire gets smothered VERY quickly...
This is why I like and prefer to use metal boxes. Then I further insulate the out door receptacle boxes with a coating of construction foam over the inside portion, mostly to keep out bugs and dirt out of the walls and to shut down air circulation. But will also help smother and isolate a fire. The aerosol construction foam I use only burns if I hold a propane torch to it.
2011 white SL leaf with 2014 batt.
Chargers: Panasonic brick moded for 240v, duosida 16a 240v and a 10kw setec portable CHAdeMO
Location: 88103

LeftieBiker
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Re: Idea for apartment dwellers: 'host' charging through window

Fri Feb 08, 2019 2:20 pm

NEC 210.17 states that a receptacle used for charging an electric vehicle shall not contain other receptacles. Each electric vehicle charger is to be on its own dedicated circuit.
This isn't practical for 120 volt charging, and is generally ignored (except for not using more than one EVSE). Extension cord use is a grey area: I definitely see why it's prohibited, but a best-case setup, with high quality, heavy cord, good outlet, and no foot traffic over the cord, isn't very unsafe.
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2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
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PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

Oilpan4
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Re: Idea for apartment dwellers: 'host' charging through window

Fri Feb 08, 2019 6:34 pm

LeftieBiker wrote:
NEC 210.17 states that a receptacle used for charging an electric vehicle shall not contain other receptacles. Each electric vehicle charger is to be on its own dedicated circuit.
This isn't practical for 120 volt charging, and is generally ignored (except for not using more than one EVSE). Extension cord use is a grey area: I definitely see why it's prohibited, but a best-case setup, with high quality, heavy cord, good outlet, and no foot traffic over the cord, isn't very unsafe.
I use an extension cord too sometimes.
Problem with most cords is even if they have heavy 12 gauge conductors the cheap thermoplastic moulded ends can burn up. I have smoked them just using them on a little 1.5hp air compressor.
My evse extension cords are all 240v 6-20 plugs and receptacles on each end. Since I can not go to the hard ware store and buy a 6-20 ended cord I made my own by putting commercial grade replacement ends on a 12 gauge STW cord. I would prefer sjoow cord but the STW was pretty much free.
If you live up north trust me, pay extra, you want the sjow or sjoow cord in the winter.

If your house is wired to code and you use an outside 120v receptacle, these individual outside receptacles should be in their own dedicated circuit, or at the very least all the outside ones should be on their own circuit (old code).
Last edited by Oilpan4 on Fri Feb 08, 2019 8:02 pm, edited 1 time in total.
2011 white SL leaf with 2014 batt.
Chargers: Panasonic brick moded for 240v, duosida 16a 240v and a 10kw setec portable CHAdeMO
Location: 88103

LeftieBiker
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Re: Idea for apartment dwellers: 'host' charging through window

Fri Feb 08, 2019 7:01 pm

The EVSE we have outside the garage is a Toyota PIP unit, with the cord run through the wall and plugged in inside (and a plastic garment bag over the unit). The Nissan dual voltage cable is plugged into a short appliance extension cord, and then into an outlet, all inside the garage, so I can charge while the Leaf is inside. I've been wanting either a 240 volt circuit or at least a 20 amp dedicated 120 volt circuit for years, but it hasn't happened yet.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
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PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

Quothmar
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Re: Idea for apartment dwellers: 'host' charging through window

Sat Feb 09, 2019 8:31 am

Oilpan4 wrote:NEC 625.29 states the evse shall be plugged into the receptacle and not be plugged into an extension cord.

NEC 210.17 states that a receptacle used for charging an electric vehicle shall not contain other receptacles. Each electric vehicle charger is to be on its own dedicated circuit.

NEC 240.4 requires a 15 amp breaker on a 14 gauge circuit.

If you plug a 16 amp load on a 15 amp breaker it may trip after 2 or 3 hours.

So the NEC answer to can I plug an extension cord into some random apartment receptacle that may be on a 15 circuit to charge an EV is no, no and no. Or just no and no.

Ignore NEC, test your smoke detectors for real and meet the fire department.

Any other questions?
So you're quoting the NEC now. That's fine, but now we're discussing American law and not physics. In your previous post, you had put forth an argument about the constitution of wall insulation materials, suggesting that if the wiring approached 60 degrees Celsius, it could start a fire. My question was whether you could supply a physical justification for this claim, deriving the probability of a fire from the known properties of cellulose insulation and from the laws of thermal physics.

If you're not into complex mathematical derivations, that's fine. I understand that this forum is not a physics course. But that is what you would need to justify any claim about the probability of a fire.

Although I use a JLong extension cord, the fact that it pulls only 1300 watts on a 120-volt outlet means that it only draws 1300 / 120 =~ 11 amperes, well below your example of a 16-amp load. And I did previously say that we were stipulating trickle-charging, and that we were putting the EVSEs on timers so that only one would be charging at a time.

Now obviously, we couldn't do this with 'some random receptacle' if we had reason to believe it was defective. But if you're going to argue that it's simply a bad idea, you would need to supply the physical derivations to obtain the probability of a fire, and use that probability in a weighted calculation of the favorability of alternative actions in respect of their possible outcomes. These outcomes include, on the one hand, smoggy streets and parking lots in urban cities (very annoying, and also high probability), and on the other, a fire (devastating, but possibly also very low probability).

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