Ground to Feeder Panel
- Thread starter mjhutchins
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If you would be following the post 2005 rule and running a new feeder from main to sp, what do you think?
If your talking about a 4 wire setup replacing the 3 wire drop between the pole and house, good luck with that. It has been proposed, but never has gotten off the ground- sop is still the edison ckt for those drops.
FionaZuppa
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- AZ
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- Part Time Electrician (semi retired, old) - EE retired.
this part ?? or, what about 250.32 did i not read ?
250.32(B)(1)
Any installed grounded conductor shall not be
connected to the equipment grounding conductor or to the
grounding electrode(s).
as-is, OP says "a grounding rod was used". hmmm, sounds like a violation ? <-- note what is or is not used, etc.
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A grounding electrode would be required for any code cycle metioned in this thread, whether or not an EGC is required is dependent on the code cycle in place when the feeder was installed.
The basic reason for the change is that a parallel neutral path might be installed at a later date. By requiring an EGC (which would be bonded to the GE) and an isolated neutral this would never be a concern.
Simple solution to a potential problem.
Roger
FionaZuppa
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- Part Time Electrician (semi retired, old) - EE retired.
"a" grounding electrode? just one ?
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- Massachusetts
Maybe, the requirements are the same as if it where a service.
So any electrodes that are already present and if none are present installers choice of made electrode(s) needed to create a grounding electrode system.
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There are no safety issues with a combined grounded/grounding conductor to a separate structure as long as there are no parallel paths. The reason I think a dedicated equipment ground is a good idea is the same as what Roger said. It's also why I said there should be an exception for meter pedestals in that other thread. Nobody is ever going to run a gas line or water line out to their electric meter.
FionaZuppa
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- AZ
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- Part Time Electrician (semi retired, old) - EE retired.
ok, so, if i have a older 3-wire 240v dryer and i buy a new dryer that has a 4 prong plug, would it be ok to keep the 3-wire BC, swap the recept to a 4-wire and just tap the egc into the N inside the recept box? certainly much less likely vs feeder that anyone would parallel anything up to that recept, so from a safety hazard view its perfectly safe for anything plugging in since the old 3-wire is using N as egc ?
Where are you buying dryers with factory provided cords and cord caps?
Since you already have a cord on the old dryer just swap it with the new one.
Roger
No- do not do that- you could end having it concluded by someone else that there is a 4 wire ckt there when there is not. Continue to use the old 3 wire receptacle if keeping the unaltered 3 wire feeder.
You install a 3 wire cord on the dryer and make sure the ground jumper between frame & noodle inside the the dryer is attached in situations where there is existing three wire feeder & rec/250.140 exceptions.
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- Massachusetts
FionaZuppa
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- AZ
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- Part Time Electrician (semi retired, old) - EE retired.
for a std 3-wire BC with new "4 wire" dryer, you would take the green egc and tie that to the N terminal on the dryer terminal block, essentially making the dryer like the old one. and the reason why new installs require true 4-wire BC is ??
growler
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- Atlanta,GA
I think you are looking at this all wrong. The NEC doesn't cover dryer installs it cover the building wiring. If you install a new dryer circuit it must be a 4-wire but if the circuit that exist is only a three wire then you are not requried to change it just because you bought a new dryer.
Go to any of the big box stores and you will find plenty of three wire dryer cords for sale and you can buy the old three pronged dryer receptacles ( as replacements ).
One issue w/ the old 3 wire setup was the shock hazard that could arise if the neutral was compromised. With that being said, idk how much of a factor that risk played into getting the code changed for those ckts roughly 20 yrs ago- the NEC considered the 3 wire practice reasonably safe for an awfully long time and you would think it would have been changed sooner had there been enough incidences of shock/electrocution.
FionaZuppa
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- AZ
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- Part Time Electrician (semi retired, old) - EE retired.
if its now changed for a safety reason, then pulling a egc (if reasonably doable) out to a old 3wire feeder sub, makes sense to me to just do it. the same safety issue that exists for a 3wire dryer also exists for the items plugged into a 3wire sub, right??
i cant see arguing about why nec kept things in nec code for a long time, but its now changed for the better, and you keep arguing that it was safe for the 1st 50yrs of nec code, so its safe today to. it was changed for a reason.
:huh:
I was pointing out the fact that the NEC did indeed consider that setup safe for dryers for a long time- in any one of the dozen or so code cycles that spanned the half century the 3w was legal for dryers they could have required an egc, yet they did not (that's a huge clue about the frequency of real dangers/incidents encountered w/the design considering how widespread the use of it was). And I acknowledged that I don't know the reason for the 1996 switch and speculated that if it was that problematic they obviously would have changed it sooner.
All the rule allowing those old dryer feeders does is make it permissible to continue using the old style feed if its unaltered and you will be using it to feed 3 wire grounded thru neutral equipment.
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FionaZuppa
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- AZ
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- Part Time Electrician (semi retired, old) - EE retired.
........... and for many years considered a safety hazard.
an existing 3wire dryer outlet is likely a burden to achieve a homerun egc. so what about tying dryer egc to another egc point vs keeping egc tied to N?
in case of OP though, if the conduit is large enough AND a pull can easily be done, why not do it? it's safer, right ?
Borrowing an egc from an existing ckt? Problem there is you need to pick up at least #10 egc (remember its a 30a dryer) from another branch ckt that goes all the way back to the panel and most of the time by the time you run your separate wire from the other branch ckt, conceal it, and terminate it to your new 4w dryer receptacle, you could have just pulled new cable.
Or you could save many folks with these old feeds a lot of time, aggravation and money by invoking 250.140 exceptions.........
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