ajdelange
Well-Known Member
- First Name
- A. J.
- Joined
- Aug 1, 2019
- Threads
- 9
- Messages
- 2,883
- Reaction score
- 2,317
- Location
- Virginia/Quebec
- Vehicles
- Tesla XLR+2019, Lexus, Landcruiser, R1T
- Occupation
- EE Retired
Number 6 is number 6. It has a fixed impedance per unit length and will dissipate the same amount of power per unit length. It's a question of where that power goes or, more particularly, of how much temperature rise that dissipation leads to and what temperatures can be tolerated by insulation, enclosure etc. Thus the current rating of a conductor depends on how many wires are bundled, how many of them are carrying full current, whether they are in a cable or a conduit and the ambient temperature. NN-B is intended to be used enclosed in a wall and does not have particularly temperature resistant insulation. Therefore, it is permitted to carry limited amounts of current and if it is hotter than normal even less.I did not use NM-B, and probably should have specified. Indeed although NM-B conductors are rated at 90, the cable itself must be sized using the 60 degree rating.
Sure it can if it is provisioned to less than or equal 40A. But I guess the nature of the provisioning is what's in question. What I thought was interesting is that it can only be plugged into a NEMA 14-50 in Canada.This unit cannot be plugged in and meet NEC 625.44.
I thought it might be something like that. But then the user can set the current in a Tesla Gen 2 or Gen 3 HVSE too, in the latter case using the WiFi interface.The two areas where it would fail are:
User selectable amperages. In fact, the electrician is instructed to have the homeowner complete the installation using the app to set the amperage.
Umm. The circuit breaker in the panel provides protection (belt). If the driver asks for 48 A on EVSE connected to a 30A circuit the breaker will trip pretty fast. Furthermore, if the car detects high impedance (a smaller circuit will have this because of smaller wire size) it will shut down. But in a proper installation his EVSE would have been provisioned to refuse to charge if he asks for more than 24A. That's the suspenders. If anyone can willy-nilly change the maximum available current we lose belt and suspenders protection. Belt only is doubtless sufficient protection most of the time but the codes wouldn't require the suspenders too if they hadn't saved people from some nasty situations. But what to do? One answer is to allow only the electrician to set the max level. A typical way to do this is to have an "installer's app" and a "users app" with only the first allowing change of the amount of current. Another way would be to restrict current control to the manufacturer. Your electrician would have to call the factory and request that the factory set the device. Another solution would be to only manufacture units of fixed capacity which would really be the variable capacity unit provisioned before delivery by burning fusible links.I consider the ease in which an owner can set, either accidentally or intentionally, the EVSE to draw over the capacity of the circuit it is installed on to be a fairly major issue.
Everything coming on the market these days can charge from a J1772. So ???. Clearly though few new vehicles are going to be asserting the "requires ventillation" signal.Since virtually nothing on the market in recent history uses a J1772 plug and lead acid batteries, the ventilation requirement does not really pose a safety hazard.
If the receptacle is no bigger than 50A and the unit is provisioned for no more than 40 A what's the problem? There better not be one as untold numbers of these are sold on Amazon etc. every day.This unit cannot be installed using a plug and meet the NEC and therefor most (all?) electrical codes. Hardwired installations are better, but still have issues meeting code.
I do agree that Art. 625 could use some cleaning up.
Anyway, thanks for responding to my question.
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