Updating the receptacle to 4 wire may not be possible without rewiring. I might suggest a note stating the receptacle is not as safe as the current requirements for a separate neutral and ground 4 prong receptacle.
A 4 prong receptacle for an oven would be for a 120/240 appliance. There are straight 240 volt ovens that would only require 3 wires. I have never seen an oven with a cord and plug connection. All have been hardwired with a flexible conduit whip.
In the illustration, it is written, “in the 4 prong configuration, the neutral and ground pathways are carried by 3 separate wires”
How can two (2) separate pathways, neutral & ground paths, evolve into 3 separate wires?
You need to pay attention to what you don’t bother reading! It’s no wonder you are always catching hell for your posts!!
Seriously, we are in the upgrade business now? GFCI and AFCI should be mentioned as well? How about new service to include an exterior service disconnect? Why not a 4 wire service up-grade? And while you are at it, get rid of that old car in the driveway. It does not have 4-wheel disc breaks or the rear passenger door safety latches for children. 
And code? We are bringing homes up to code?
You learn how do develop thought yet?
Evolve indicates, a gradual development or change.
Yiou forgot child proof outlets!
It should say two separate wires not three.
Thank you.
I am not being facetious, Robert. I truly appreciate, as well as all the members here, your fine tuned ability to read and understand the context within the statement that was given, by anyone unbiasedly.
I say this for it, my statement, appeared lost on a particular member I will not mention, that would rather abruptly disapprove and lambast a fellow InterNACHI member instead of acting professional and waiting for others to chime in.
Thanks again.
You are more diplomatic than I.
I agree, your suggestion is more accurate and applies to what we do in the field. And being educated as to when the change took place is also helpful.
Same here. Only the slide-in combo range/ovens have the plug in my experience.
Yes the graphic specifically mentions electric ranges which are different from electric wall ovens. Wall ovens are typically hardwired via a factory installed whip due to the need for high temperature conductors within the whip.
I always note in the report if the dryer receptacle is a 3 or 4 prong receptacle but have yet to recommend an upgrade from a 3 to a 4 prong, I don’t consider a 3 pronged dryer receptacle a defect.
I also don’t consider 2 pronged 120 receptacles in a 1950s home a defect in some locations either.
Sometimes it seems that common sense seems to be going going gone.
In your opinion, would you consider a four-wire dryer cord safer than a three-wire cord?
According to SOP…
“unsafe: In the inspector’s opinion, a condition of an area, system, component or procedure that is judged to be a significant risk of injury during normal, day-to-day use. The risk may be due to damage, deterioration, improper installation, or a change in accepted residential construction standards.”
With that being said, I normally make what I call a soft recommendation, meaning I’ll say something like, “Consider replacing…” or “consider upgrading…”, and why. Because it’s not just a simple matter of “upgrading to a 4-prong”. The wiring would have to be upgraded as well.
All great points Richard, which SoP is that?
InterNACHI SoP.
That is the InterNACHI glossary definition of unsafe. The question remains if the lack of a 4 wire dryer outlet is “unsafe.” Even the definition given is limited by the phrase "In the inspector’s opinion . . . "
That sounds like a good compromise after all the 3-wire is still permitted by the NEC for existing installations. The 4-wire is safer which is why they removed using a 3-wire circuit for new installations from the NEC in 1996. As you’ve stated upgrading from a 3-wire branch circuit to a 4-wire branch circuit can be costly because it may not be a simple task.
Agreed.
I would prefer the graphic explain the newer 4-prongs are safer and why.
The author says “The inspector should recommend the upgrade…” In order to make the recommendation for an upgrade, the author of the graphic must have concluded, according to NACHI definitions, the 3-prong is Unsafe and to be a significant risk of injury during normal day-to-day use.
Not sure how many agree this is a significant risk.
Under normal operating conditions, lack of a 4-wire is safe. Under normal operating conditions, lack of a ground on 120V equipment with a metal casing is safe…UNTIL IT’S NOT!
I am quite sure you cannot explain why a 4 wire dryer outlet is MORE safe than a 3 wire outlet!
. . . driving a car is safe . . .UNTIL IT"S NOT!
No step you will ever make or breath you will ever take is without risk!