Char(g)ing loads are potentially far more dangerous than startup surges.
Yes, that's my point. Plugging in an EVSE because a breaker doesn't trip immediately with an overload is dangerous, to say the least.
Char(g)ing loads are potentially far more dangerous than startup surges.
Oilpan4 said:A good test would be if you can draw more than 150% amps over a breaker for more than 3 minutes it's probably bad, unless it's some old obsolete style of breaker, that may be normal for them and likely the reason they're obsolete.
Quothmar said: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?
When you say it's 'dangerous', it makes me wonder how that should be defined. There is, obviously, the danger that gas fumes have on pedestrians and on the ozone layer, and then as you mention there's the danger of a fire if circuits are overloaded. What if the danger of a fire occurs with something like 0.001% probability? I don't know enough about electricity to calculate the figures, but I think some kind of cost-benefit analysis would weigh in.
LeftieBiker said:Indeed. The likelihood of a fire in an overloaded circuit goes up over time, but can be high in Minute One if the wiring is old and/or in poor condition. This is NOT something you want to ignore or shrug off. Just running a circuit at 100% of capacity for many hours is risky. Running it over that is like smoking with a gas leak in the house and one window cracked open.
Quothmar said:LeftieBiker said:Indeed. The likelihood of a fire in an overloaded circuit goes up over time, but can be high in Minute One if the wiring is old and/or in poor condition. This is NOT something you want to ignore or shrug off. Just running a circuit at 100% of capacity for many hours is risky. Running it over that is like smoking with a gas leak in the house and one window cracked open.
Are you suggesting it's a bad idea for an apartment-dweller with 14 gauge wire to trickle-charge even one car from a room circuit?
Oilpan4 said: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.
WetEV said:Quothmar said: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%.
Quothmar said:Oilpan4 said: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/insulation-temperatures-d_922.html
https://en.wikipedia.org/wiki/Insulation_system#cite_note-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 said:Quothmar said: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 said: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...
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.
LeftieBiker said: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.
Oilpan4 said: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?
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