Recent content by wwhitney

No idea on that question. I just knew that there is a system for naming refrigerants and related fluorochlorohydrocarbons, but I had to look up the details. Cheers, Wayne

Both R-134 / HFC-134 and R-134a / HFC-134a are C2H2F4, but they are different isomers. R-134 / HFC-134 is CHF2 - CHF2 (two fluorine atoms bonded to each carbon). While R-134a / HFC-134a is CH2F - CF3 (one carbon has 3 fluorine bonds, one carbon has just one fluorine bond). Cheers, Wayne

No. R134a and HFC134a are the same things. The entry you have above labeled R134a gives the molecular formula of R134 / HFC134 (no a after it). No idea if the rest of the data you quoted is correct or not. Cheers, Wayne

For a dwelling unit, where there's only one voltage system present, there's no need to use any particular colors (edit: for the hots). Each ungrounded (hot) can be any color except green, white, or "natural grey". But conventionally you'd distinguish one of the ungrounded conductors from the...

Yes, sorry, I misspoke, the 16.5A MCA is used. Although with an inverter driven compressor, I expected it would be reasonable to use the 13.4A figure, since there should be no startup surge like with a motor started "across the line" (full AC voltage switched on immediately). But there's no...

That's mostly true. But nuisance tripping becomes a safety issue when users ignore it and repeatedly reset the breaker rather than downsizing some of the equipment or changing their operating behavior. Or when they upsize the breaker to keep it from tripping. Since you mentioned this is a...

The receptacle in the OP is almost certainly the service receptacle required to be installed within 50 ft (?) of the HVAC equipment. So it would not be likely to see a large load while the HVAC equipment is also running at full load. I don't see any NEC problem with installing a 20A circuit...

Right, there's at least 2 obstacles to being able to actually use that for #12 Cu. First 240.4(D) has limits on OCPD size for #14, #12, and #10 AWG Cu that do not apply for larger sizes. Second equipment terminations are limited to 75C at most, so any conductor segment terminating at a breaker...

No, #12 AWG Cu is limited to a maximum 20A OCPD, with only a few exceptions. HVAC equipment and motors are the most common exceptions, and EVSEs are not an exception. So that means that you have 40A - 16.5A = 23.5A of remaining capacity, and so the maximum EVSE size is 0.8 * 23.5A = 18.8A. In...

New circuits would require an EGC, but if you have an existing EGC-less circuit with a 10-30 receptacle, and the receptacle fails, you are allowed to replace it with a 10-30. I think you mean 6-XX is 2 hots and a ground; 14-XX is 2 hots, a neutral, and a ground. No code problems with a 30A...

Comments on above: - L1 and L2 are 120VAC from ground or neutral but opposite polarity, so they is 240VAC between them. - For whatever reason, the nomenclature standard for cords (on equipment) is to count the EGC (grounding wire), but for building wire (inside the walls), it is not to count...

Not super familiar with NEC Table 400.5(A)(1) on the ampacity of cords, but it distinguishes between the case of 2 current carrying conductors and 3 current carrying conductors. If you were using your 10/4 (which counts the EGC) for 3 phase power, then that would definitely be 3 current...

Grid tied PV means the grid provides the voltage waveform, the grid-tied PV inverter just has to match the grid and has no control over any parameters. Off grid PV means the PV and/or battery inverter provides the voltage waveform, and various parameters may differ from a grid source. So the...

There are just 2 power pins. And 2 points define only a single voltage--for L2 charging, 240V (or 208V if supplied by a three phase 208Y/120V system). So no 120V source required. [Does anyone happen to know, if you plug the stock L1 EVSE into a receptacle with Hot/Neutral reverse, does it...

The following is true in theory, but I don't know enough of the specifics of the Leaf's charger to be sure it's true in practice: If it's really just for charging the Leaf, you don't need split phase (if it makes a price difference). You could use a 240V 2 -wire inverter. You'd probably need...