National Electrical Code --- Electricians are Special People

[SwampNut]

EVSEs will not work without a ground, they test it before startup.  Nearly all generators have floating grounds for safety.  I have a shitty EMS in there and a nicer one to go in soon.  But that isn't related to this.

 

Also to charge the EVs from the TT-30 plug I need an adapter that takes one of the hots from the 14-50 to the neutral on the TT-30.  Otherwise the 5-20R can only charge at 12 amps (80% constant load of 5-15 because the male plug on the EVSE is a 15 not 20).

 

To add to all the fun, it's potentially (heh) dangerous to run the bonding plug and plug in the trailer, because now you've violated the "only one bonding location" rule.  But there really is nowhere in the trailer to kill yourself on a broken neutral.

 

So yeah...this is all very "special."

 

[xrated]

8 hours ago, SwampNut said:

EVSEs will not work without a ground, they test it before startup.  Nearly all generators have floating grounds for safety.  I have a shitty EMS in there and a nicer one to go in soon.  But that isn't related to this.

 

Also to charge the EVs from the TT-30 plug I need an adapter that takes one of the hots from the 14-50 to the neutral on the TT-30.  Otherwise the 5-20R can only charge at 12 amps (80% constant load of 5-15 because the male plug on the EVSE is a 15 not 20).

 

To add to all the fun, it's potentially (heh) dangerous to run the bonding plug and plug in the trailer, because now you've violated the "only one bonding location" rule.  But there really is nowhere in the trailer to kill yourself on a broken neutral.

 

So yeah...this is all very "special."

 

You lost me on that one......the "plug in the trailer" part of it.  Can you explain in more detail please.

[SwampNut]

So as you know, ground and neutral should be bonded in only one place.  I believe (have been told) that the trailer has a bonded neutral-ground in its panel (not 100% sure).  If I have my little bonding plug, that's two of them, and that should never be done.  I guess I need to test it.  And if it's not bonded, then I probably should put a real bond on the generator (more than that #22 jumper)?  Wouldn't the trailer floating be a danger itself?

 

 

 

 

[xrated]

On 7/9/2024 at 8:59 AM, SwampNut said:

So as you know, ground and neutral should be bonded in only one place.  I believe (have been told) that the trailer has a bonded neutral-ground in its panel (not 100% sure).  If I have my little bonding plug, that's two of them, and that should never be done.  I guess I need to test it.  And if it's not bonded, then I probably should put a real bond on the generator (more than that #22 jumper)?  Wouldn't the trailer floating be a danger itself?

 

 

 

 

I'm not going to go out on a limb here, but I know for a fact that my trailer (50A service using the NEMA 14-50 plug and recept), at the breaker panel in the trailer, there is NOT a bonded neutral ground connection.  I believe almost, maybe all trailers are the same way, and that makes sense because under normal circumstances, the trailer receives it's power from a cord via "shore power".  That power source, the shore power, is fed by a neutral/ground bonded supply.  So if the trailer also was neutral/ground bonded that would violate the NEC rule about only ONE neutral/ground bond.  So if you power the trailer from a generator that is neutral/ground bonded inside the generator, life is good.  If you power it from a floating neutral type generator, you will need to provide that neutral/ground bond and many folks do that with the 120VAC plug like you pictured earlier with a wire placed between the neutral and the ground connection inside the plug.

 

Edited to add answer to the last part of your above question..... "Wouldn't the trailer floating be a danger itself?"  Absolutely yes.  If there is not a path back to ground, and there is an issue with a device or even the wiring itself whereby the hot wire came in contact with some metal part of the trailer, that would cause the trailer to have, what is commonly called "hot skin".  It was probably named that because in a situation like that, you brush up against the side of a trailer and some of it is metal or some part is metal, you get shocked if you become the path to ground.  Depending of course on how well you are "grounded", the shock could be kind of just a tingle, all the way to full blown 120VAC travelling through your body.  In those two examples, think of touching a hot skin trailer and you are wearing rubber boots and the ground is dry.....maybe nothing at all or just a slight tingle.  Then on the opposite end of the scenario, you are barefoot, stand in a puddle or morning dew on the grass or whatever and you touch that same thing......possibly the full 120VAC from the hot skin, through you, and to ground.

Edited August 2 by xrated

[SwampNut]

This makes it sound like floating ground on generators is the wrong thing for most use cases.

[xrated]

1 hour ago, SwampNut said:

This makes it sound like floating ground on generators is the wrong thing for most use cases.

It just depends on what you are going to use them for.  In my case, I HAD to have it for my application.  I bought a 15Kw peak (12Kw running) "portable" Westinghouse generator that is dual fuel and uses the NEMA 14-50 setup.  I am using it for backup power at the house in the event of a power outage.  I went the "cheap" route and instead of buying a large manual or automatic transfer switch system, I am using the main breaker lockout method and bringing the generator power into that house breaker panel via a double pole 50A breaker.  With that type of setup, you have to turn the house main breaker to the off position and then slide a moveable "lockout" up into position to prevent the main from being turned back on.  When you do that, it then allows you to turn on the 50A double pole breaker that is the generator input for the house panel.  So when that happens, you are using the existing neutral/ground bonding inside the house breaker panel instead of having a neutral/ground bond in the generator itself.  It is completely up to code from NEC doing it this way, and of course is a lot less expensive that doing the manual or automatic transfer switch method.  The drawback is obviously, if we aren't at home, nothing happens when the power goes out......because the generator does not start by itself and none of the switch is done automatically.  For the few times that we lose power here, I decided to go that route.......plus I'm retired so I'm home a lot more than most folks that are working.  The generator that I bought came with a generator neutral/grounding bond inside the generator, but the manual gives you directions on how to remove it if you need a floating neutral/ground bond......which I did.  I of course saved the bonding jumper and clearly marked the generator as "Neutral/grounding BOND REMOVED....

 

It's a hoss.......close to 600 lbs when fully fueled with 17 gallons of gasoline, but a good set of solid wheels on it and handles for moving it outside my garage if/when needed.