ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Burning out of return(white) side of 120volt rec
by crselectric. 06/14/19 02:15 AM
Video door bell causing chime activation of coil
by JoeTestingEngr. 06/13/19 12:43 PM
Troubleshooting Voltage Drop Across Relay
by gfretwell. 06/09/19 11:49 AM
Apple Recalls Three-Prong Wall Plug Adapters
by Admin. 06/05/19 09:06 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 13 guests, and 19 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
flexibility-FMC #90482
11/22/04 05:19 PM
11/22/04 05:19 PM
S
Steve T  Offline OP
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
What is everyone's opinion on "installed for flexibility" when refering to an equipment grounding conductor being required?

Does this include a whip that is installed to facilitate installation and removal of such appliances as residential dishwashers or stoves?

2017 / 2014 NEC & Related Books and Study Guides
Re: flexibility-FMC #90483
11/22/04 10:41 PM
11/22/04 10:41 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,365
Estero,Fl,usa
I worked around the computer biz for 30 years where flexible wiring methods were the standard. I think they all need a hard wire ground. I have seen far too many that have separated from the connectors.
Joe Tedesco may have some of my pictures. They were in the IAEI magazine a couple times


Greg Fretwell
Re: flexibility-FMC #90484
11/24/04 05:53 PM
11/24/04 05:53 PM
S
Steve T  Offline OP
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
So what about AC cable? Doesn't it come loose too?

Re: flexibility-FMC #90485
11/24/04 06:32 PM
11/24/04 06:32 PM
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
Greg: Remind me about the images and what was included in them. I think I still have some and one with about a size 12 boot with the underfloor in a computer room.

The reason for the "flexibility" rule calling for the EGC at all times is because CMP 9 went out into the field and found that most of the compressors on roofs were with loose connections, and the flexible metal conduit that was used was not secure in many instances.

I think that the they did this around the 1981 or 1984 NEC cycle. Maybe someone can check the TCR and TCD


Joe Tedesco, NEC Consultant
Re: flexibility-FMC #90486
11/25/04 01:46 AM
11/25/04 01:46 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,365
Estero,Fl,usa
Steve I will say I don't see any difference between AC, FMC or LFMC in this regard. If it is not installed to 300.11 standards (secured next to the box) it should have a ground wire. Whenever you have a whip to something that can move around or where the whip can be moved around you are going to loosen a certain percentage of the connectors. At least one of the pictures I sent into IAEI shows a separated FMC connector under a computer room floor with about 4" of conductor exposed. Without a green wire ground that equipment was floating. The same can happen to T bar lights, pump motors, wall ovens or whatever you hang out on a whip. Fortunately I never had the fight when I was an inspector. Insulated EGCs were required in all state contracts, even in EMT, IMC or RMC.


Greg Fretwell
Re: flexibility-FMC #90487
11/25/04 08:03 AM
11/25/04 08:03 AM
S
shortcircuit  Offline
Member
Joined: Jun 2004
Posts: 610
massachusetts
I have recently noticed that furnace manurfacturers that use FMC to connect between the controls on the unit now have a insulated EGC installed in their factory assembled units.I always wondered how they got away without the ECG in the flex.

shortcircuit

Re: flexibility-FMC #90488
11/25/04 11:37 AM
11/25/04 11:37 AM
J
John Steinke  Offline
Member
Joined: Apr 2001
Posts: 518
Reno,Nv., USA
I will have to agree with gfretwell; when the appliance is likely to be physically moved (as with a dishwaser), and not simply vibrating (like a transformer), I believe that it is wise to run a grounding wire.
his also applies when the flex is likely to be snagged, or tripped over, etc. I've just seen too many connectors -especially "jakes"- come loose. Indeed, I will often install liquid-tight for this reason; their connectors are more substantial.

Re: flexibility-FMC #90489
11/25/04 11:54 AM
11/25/04 11:54 AM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
None of these installations are allowed to transmit stress to the connectors.

Other than flexible whips to Luminaires all flexible cables and raceways require a support near the connector before and after the section that may be flexed. [Linked Image]

shortcircuit

Manufacturers are not covered by the NEC and comparing their work against our work can only lead to frustration. [Linked Image]

The fact is manufacturers equipment gets tested by an NTL and must pass certain tests.

We do not test our grounding paths so the code has to make a blanket statements about what will be acceptable and what will not.

I always run a grounding conductor in flexible raceway it just makes me feel better. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: flexibility-FMC #90490
11/26/04 08:00 AM
11/26/04 08:00 AM
G
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,498
Michigan USA
Bob- State of Michigan requires an EGC in all flex regardles of length. There are two exceptions: One is Flexible Metal Tubing and the other is for flex 6 feet or less when used in one and two family housing subject to the Michigan Residential Code (IRC). Most contractors pull in an EGC all the time in flex regardless. I would say one of the primary reasons electricians run flex is to avoid running EMT or Conduit. The vibration issue is secondary.


George Little
Re: flexibility-FMC #90491
11/27/04 10:30 PM
11/27/04 10:30 PM
electure  Offline

Member
Joined: Dec 2000
Posts: 4,280
Fullerton, CA USA
I always put an EGC in all flex that I install, and make sure the fittings are tight.

Sadly, I can go up to probably 8 or 9 out of 10 flex installations I find, and take them apart barehanded, because that's the way they were installed.
The same holds true for the gland nuts on LTFlex connectors.
I don't like to see it that way, but it's a fact. [Linked Image]




[This message has been edited by electure (edited 11-27-2004).]


Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Radar
Radar
Los Angeles, CA
Posts: 349
Joined: April 2004
Show All Member Profiles 
Top Posters(30 Days)
Khombo 2
Popular Topics(Views)
255,717 Are you busy
191,687 Re: Forum
181,470 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.043s Queries: 14 (0.015s) Memory: 1.0130 MB (Peak: 1.1843 MB) Zlib enabled. Server Time: 2019-06-17 17:14:04 UTC