Bonded versus Floating Generators

[oldjohnt]

Ive observed soooooooo much confusion all over the net (some of which is a lay persons opinion NOT any professional) as well as some here regarding the use of Generators for RV power and if they should be Bonded or Floating so I will try to shed some light on the subject.

1) Some smaller portable gensets are factory wired with a Floating others a Bonded Neutral FOR GOOD REASON !!!!!!!!!!!!!

2) A typical EMS type of device will throw a fault code if the RV is connected to a Floating genset so many Bond themselves (bonding jumper etc) so the EMS works.

3) A manufacturer may ??? advise against bonding based in part on advice from legal counsel  to avoid liability since in certain situations bonding would be in violation of the NEC (Im also an attorney so believe this)

4) In a typical application where the homeowner uses a plug and cord to backfeed his home panel upon a power outage he (after main breaker is off) plugs in a cord from the genset which effectively connects the gensets Neutral to the homes Neutral  (there can be ONLY ONE NG BOND) while the homes panel (unlike RV panel) already has a Neutral Ground Bond

 THATS A SITUATION WHERE A FLOATING GENSET (NOTTTTTTTTTT A BONDED)  SHOULD BE USED !

5) Now for RV use which has a panel WITHOUT A NG BOND iffffffff a portable genset is used it should have a Bonded Neutral. The NEC calls for (portable set out gensets) bonding to a Grounding Electrode such as a driven rod SUBJECT to exceptions if portable pug n cord power tools are fed from onboard genny receptacles. To make it further complicated some OSHA regulations for construction gensets advise Bonding NG but NOTTTTTTTTTT connecting to a ground rod also for sound reasons.    

6) In 50 years of RV use every RV onboard genset Ive seen uses a Bonded Neutral and also bonding to the RV frame which suffices as the Grounding Electrode (You DO NOT need a ground rod attached to RV !!!!!!!!) but I haven't seen them all lol, there may be floaters out there NO WARRANTY..  

7) If a floating system is used and there's a short of a hot to a conductive frame or case or enclosure there's no fault current return path and the circuit breaker will NOT trip. If a Bonded system is used and the case/frame/enclosure comes in contact with a shorted hot case/frame/enclosure the breaker will trip and turn off the power 

NOTE connecting an RV to a ground rod wont help a whole lot in case of a lightning strike and rubber tires aren't a stop to a gazillion volts !!!!!!!!! Subject to the earth and resistances and connections etc etc  a ground rod will not necessarily prevent shock if you touch a hot RV skin BUT HEY IT WONT HURT AND THEY COULD HELP. The earths resistance is too high to allow enough current flow to trip a 20 to 50 amp breaker while connection to a low resistance Equipment Grounding Conductor (the bare or green) allows adequate fault current to trip the breaker and hopefully save a life........GROUND THE RV CASE/FRAME  TO THE EQUIPMENT GROUNDING CONDUCTOR can save a life in case of a hot short to frame !!!!!!!!!!!     

DISCLAIMER this is short brief NOT exact or perfect explanation it would take books and study to cover this complex subject in detail SO NO WARRANTY also Im long retired n rusty on the latest codes so again NO WARRANTY. Floating systems have a place and use as Bonded but I cant cover all that here. I prefer Bonded systems and regardless a GFCI will still work in EITHER or off utility or genset power.............. 

PS do NOT take ONLY my word for this, consult Mike Holt   Electrical Training Solutions |Mike Holt Enterprises or No Shock Zone  see what they have to say !!!!!

 Hey I try my best, yall be safe and have a great day

 

John T in RV at an antique tractor show yayyyyyyyyyyyyy

Edited August 27, 2021 by oldjohnt