ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3 4   Go Down

Author Topic: Portable Generator Grounding  (Read 1864 times)

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 925
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Portable Generator Grounding
« on: March 13, 2014, 03:51:39 pm »

Having followed this thread, it seems that even when using a small, portable Honda 3000 watt genny, a ground rod would be a good idea.
I don't see any ground connection point on these small gennys.
Thoughts or experiences?

OK, I'm splitting out this thread into a generator grounding topic. I just got a phone call back from my Honda Generator contact, and he says that EVERY modern Honda portable generator has a grounding lug, and its location is in the operators manual. So I took the liberty of downloading the EU3000 manual and found its location (though it's not real obvious). He also stated there's no single publication that shows the ground lug locations for ALL Honda generators, but perhaps that would be a good project for an intern.
« Last Edit: March 13, 2014, 03:55:54 pm by Mike Sokol »
Logged

Ray Aberle

  • Classic LAB
  • Hero Member
  • *
  • Offline Offline
  • Posts: 709
  • Located in Vancouver, WA (and serves OR-WA-ID-BC)
    • Kelcema Audio
Re: Portable Generator Grounding
« Reply #1 on: March 13, 2014, 04:33:26 pm »

OK, I'm splitting out this thread into a generator grounding topic. I just got a phone call back from my Honda Generator contact, and he says that EVERY modern Honda portable generator has a grounding lug, and its location is in the operators manual. So I took the liberty of downloading the EU3000 manual and found its location (though it's not real obvious). He also stated there's no single publication that shows the ground lug locations for ALL Honda generators, but perhaps that would be a good project for an intern.
Owning three Hondas here, they all definitely have grounding points. Some of them are just a small screw on the back (EU2000i), others (EM3500) has a bolt on the main frame.

... but I never ground them when using them.... my only generator that gets grounded is the WhisperWatt.

-Ray
Logged
Kelcema Audio
Regional - Serving Pacific Northwest (OR, WA, ID, BC)

Lyle Williams

  • Full Member
  • ***
  • Offline Offline
  • Posts: 246
Re: Portable Generator Grounding
« Reply #2 on: March 14, 2014, 03:03:35 am »

It seems to be variable with small generators as to whether the frame is connected to outlet ground.
Logged

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 925
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Portable Generator Grounding
« Reply #3 on: March 14, 2014, 07:45:40 am »

It seems to be variable with small generators as to whether the frame is connected to outlet ground.

I'm not sure that's true. Most small (under 5 KW) generators don't have their Neutral bonded to the outlet ground, but every one I've ever seen DOES have the outlet ground tied to the frame.

But let's find out. Do any of you have an example of a generator that does not have the outlet ground connected to the frame? 

Stephen Swaffer

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 307
Re: Portable Generator Grounding
« Reply #4 on: March 14, 2014, 11:33:51 am »

After doing some reading, I come to these conclusions:

Portable generators supplying only cord and plug connected or genny mounted equipment do not need a ground rod if the frame is bonded to the grounding wire-which obviously includes the receptacles.  (NEC 2014 250.34)  If supplying "premises wiring" a ground rod is required.
"
Neutral/ground bonding is only required for "premises" wiring-which is permanent OR temporary distribution-ie panels or distros.  (NEC 250.26, Art 100 definitions)

I see several references to no connections between neutral and ground downstream of the main disconnecting means. A ground neutral bond can be at the source or the main disconnecting means. Is that "or" enough to preclude both?  (NEC 2014 525.31)

I am not seeing a distinction between "less than 5kw" and "larger than 5kw".

Where am I not looking? What am I missing?
Logged
Steve Swaffer

TJ (Tom) Cornish

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2385
  • St. Paul, MN
Re: Portable Generator Grounding
« Reply #5 on: March 14, 2014, 01:11:22 pm »

After doing some reading, I come to these conclusions:

Portable generators supplying only cord and plug connected or genny mounted equipment do not need a ground rod if the frame is bonded to the grounding wire-which obviously includes the receptacles.  (NEC 2014 250.34)  If supplying "premises wiring" a ground rod is required.
"
Neutral/ground bonding is only required for "premises" wiring-which is permanent OR temporary distribution-ie panels or distros.  (NEC 250.26, Art 100 definitions)

I see several references to no connections between neutral and ground downstream of the main disconnecting means. A ground neutral bond can be at the source or the main disconnecting means. Is that "or" enough to preclude both?  (NEC 2014 525.31)

I am not seeing a distinction between "less than 5kw" and "larger than 5kw".

Where am I not looking? What am I missing?
I don't have time to follow this through now, but a quick search of some emails on this - the exemption may be in OSHA 1926.404(b)(10(ii).  NEC doesn't have jurisdiction over everything; UL/ETL and OSHA have governance as well when you get closer to a "product" rather than a wiring infrastructure.
Logged

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 925
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Portable Generator Grounding
« Reply #6 on: March 14, 2014, 03:49:18 pm »

I don't have time to follow this through now, but a quick search of some emails on this - the exemption may be in OSHA 1926.404(b)(10(ii).  NEC doesn't have jurisdiction over everything; UL/ETL and OSHA have governance as well when you get closer to a "product" rather than a wiring infrastructure.

I believe you're correct about the 5KW threshold being a UL and/or OSHA thing rather than an NEC thing. I initially found out about this 5KW neutral bonding exemption from a generator manufacturer during one of my yak sessions. IIRC there was an official online PPT presentation discussing the drill in the water scenario. I'll look through my saved files and see if I can find the source.
« Last Edit: March 14, 2014, 03:52:51 pm by Mike Sokol »
Logged

Keith Broughton

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 476
Re: Portable Generator Grounding
« Reply #7 on: March 15, 2014, 08:07:40 am »

Owning three Hondas here, they all definitely have grounding points. Some of them are just a small screw on the back (EU2000i), others (EM3500) has a bolt on the main frame.

... but I never ground them when using them.... my only generator that gets grounded is the WhisperWatt.

-Ray
Thanks Mike.
I will look a bit closer next time I have to use one of these.
Logged

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 925
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Portable Generator Grounding
« Reply #8 on: March 15, 2014, 11:12:52 am »

I don't have time to follow this through now, but a quick search of some emails on this - the exemption may be in OSHA 1926.404(b)(10(ii).  NEC doesn't have jurisdiction over everything; UL/ETL and OSHA have governance as well when you get closer to a "product" rather than a wiring infrastructure.

Correct. Here's the OSHA reference. Note that when they say the circuit conductors are insulated from the frame, that's a floated neutral. That does NOT imply that the safety ground is isolated from the generator frame.

1926.404(b)(1)(ii)

Ground-fault circuit interrupters. All 120-volt, single-phase 15- and 20-ampere receptacle outlets on construction sites, which are not a part of the permanent wiring of the building or structure and which are in use by employees, shall have approved ground-fault circuit interrupters for personnel protection. Receptacles on a two-wire, single-phase portable or vehicle-mounted generator rated not more than 5kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces, need not be protected with ground-fault circuit interrupters.

Stephen Swaffer

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 307
Re: Portable Generator Grounding
« Reply #9 on: March 15, 2014, 12:59:20 pm »

The OSHA reference specifically applies to construction sites-which of course would be a major market for genny manufacturers. And a 2 wire floated neutral would be safe, in that you really don't have a neutral per se.

If you floated the neutral on a 3 wire 240 volt system, a hot to ground fault could result in parts of the system being 240 volts to ground-obviously a much more hazardous situation.
Logged
Steve Swaffer
Pages: [1] 2 3 4   Go Up
 

Page created in 0.135 seconds with 23 queries.