2 prong outlet

[DLP1911]

I am an Electrical contractor, my customer is selling her home. The home inspector dinged my customer for reverse polarity on ungrounded non-polarized receptacles. The house is wired pre1960’s cloth 2 wire “Romex”. I cannot find any tester that performs this test. Anyone know of one? In the past to test for this I dragged a spool of #12 around outlet to outlet, that I landed one end on the ground bus in the panel and checked for the “hot” with my fluke

 

[tom baker]

A non contact voltage tester, Fluke, Klein, ect will do the job.
Before that was available, if you had a neon tester, hold one lead and use the other to look for the hot. your body capacitance limits the current. But the non contact tester is safer, I must own three of them

 

[PaulMmn]

If the outlets are un-grounded non-polarized how can you tell the polarity is reversed?

 

[DLP1911]

I have several Klein and Greenlee induction non contact testers, they are all picking up both wires, my guess for this that I do have some reverse polarity situations and maybe reading through some loads, but not sure: what do you think?

 

[tom baker]

Hmm interesting. I have not run into that.

 

[ramsy]

I am an Electrical contractor, my customer is selling her home. The home inspector dinged my customer for reverse polarity on ungrounded non-polarized receptacles. The house is wired pre1960’s cloth 2 wire “Romex”. I cannot find any tester that performs this test. Anyone know of one? In the past to test for this I dragged a spool of #12 around outlet to outlet, that I landed one end on the ground bus in the panel and checked for the “hot” with my fluke

Ask inspector what tool they used

 

[hbiss]

If the outlets are un-grounded non-polarized how can you tell the polarity is reversed?

The hot should be on the right like every home inspection course teaches you.

Seriously, there is no right or wrong here, I wouldn't waste my time. Just tell the customer that there is no problem.

-Hal

 

[kwired]

If the outlets are un-grounded non-polarized how can you tell the polarity is reversed?

Yes, if non polarized type there is no right or wrong. If one slot is wider than the other - that should be the grounded conductor.

 

[ptonsparky]

Turn the offending receptacles over if he wants all the hots on the right hand side.

 

[Hv&Lv]

I have very little respect for home inspectors, but make quite a bit of money from their ignorance.
i have seen one inspector that had a two prong adapter on his three prong tester. There is a company that makes one which has a retractable ground pin.

either way, he’s wrong...

 

[al hildenbrand]

I have several Klein and Greenlee induction non contact testers, they are all picking up both wires, my guess for this that I do have some reverse polarity situations and maybe reading through some loads, but not sure: what do you think?

I question your saying these receptacles are "non-polarized receptacles." I suspect your client's receptacles are, in fact, polarized. Look at this image of a polarized duplex receptacle:

The longer slot is required to be connected to the grounded branch circuit conductor. A true "non polarized non grounding receptacle" has two slots that are exactly the same size as each other. A true "non polarized non grounding receptacle" is very rare, in my personal experience, as the NEC was changed in the 1920s to prevent their use.

If your client's receptacles are genuinely "non polarized" your inspector may comment about them, but he can't require them to be wired in a polarized manner. A non polarized receptacle can't be made into something it is not by reversing the branch circuit conductor connections.

As for testing the wiring in this situation, your method of stringing out an insulated conductor that is connected to a known Equipment Grounding Conductor (EGC) is, in my opinion, your first, best method to make quick, accurate measuements of the existing two wire cloth romex wiring method.

 

[PaulMmn]

I question your saying these receptacles are "non-polarized receptacles." I suspect your client's receptacles are, in fact, polarized. Look at this image of a polarized duplex receptacle:
View attachment 2551844
The longer slot is required to be connected to the grounded branch circuit conductor. A true "non polarized non grounding receptacle" has two slots that are exactly the same size as each other. A true "non polarized non grounding receptacle" is very rare, in my personal experience, as the NEC was changed in the 1920s to prevent their use.

If your client's receptacles are genuinely "non polarized" your inspector may comment about them, but he can't require them to be wired in a polarized manner. A non polarized receptacle can't be made into something it is not by reversing the branch circuit conductor connections.

As for testing the wiring in this situation, your method of stringing out an insulated conductor that is connected to a known Equipment Grounding Conductor (EGC) is, in my opinion, your first, best method to make quick, accurate measuements of the existing two wire cloth romex wiring method.

Pre-1960 it's likely the outlets had 2 identical slots. My house back in NJ was of the 'old' sort, with the outlets in the living room (and elsewhere) being the non-polarized non-grounded variety.

 

[Barbqranch]

My parent's house, built in 1948, also had non-polarized outlets, where you needed to file off the offending wide spot at the tip of a lamp plug.

 

[al hildenbrand]

Pre-1960 it's likely the outlets had 2 identical slots. My house back in NJ was of the 'old' sort, with the outlets in the living room (and elsewhere) being the non-polarized non-grounded variety.

I'm not saying they don't exist. I've seen them as well.
I'm saying they were non-NEC from the 1920s, and I'm reporting in my own experiece they are not "likely."

 

[jaggedben]

My parents house has a few non-polarized outlets. I'm sure that how rare they are in any given area depends on the housing stock.

 

[tortuga]

We call them crows foots or a 'T slot', they are really hard to tell that they are polarized. They were rated for 15A 125V or 10A 250V AC /DC
They are polarized its extremely hard to tell the difference in the size of the slots, but if you pull one out they will have silver and brass screws.
They are often crusted with paint so much you cant tell the slot size.
We use an Ideal 'sure test' to test them.

 

[al hildenbrand]

We call them crows foots or a 'T slot', they are really hard to tell that they are polarized. They were rated for 15A 125V or 10A 250V AC /DC
They are polarized its extremely hard to tell the difference in the size of the slots, but if you pull one out they will have silver and brass screws.
They are often crusted with paint so much you cant tell the slot size.

Yes. Exactly. Great set of photos. The modern zip cord molded male plug may have an "identified" blade wide enough that it will hang in the phenolic slot.

 

[tortuga]

Now if anyone on here ever finds a double T slot cord cap in the wild that would amaze this code historian.
Here is a 1939 catalog page showing one:

 

[480sparky]

FIY, what the UL White Book says about plug-in testers:

OUTLET CIRCUIT TESTERS (QCYU)
GENERAL
This category covers portable devices with fixed attachment-plug blades, or probes attached to flexible leads, used to indicate various wiring conditions in 15 or 20 A branch circuits by a pattern of lights or other similar means along with markings or instructions to identify the probable wiring
conditions which cannot be determined by the tester.
The devices may include provisions for checking the functions of a ground-fault circuit interrupter (GFCI) connected to the branch circuit, or
for indicating that a branch circuit is connected to an arc-fault circuit interrupter (AFCI).
AFCI indicators operate by producing a waveform similar to an arc fault. Since these devices cannot produce an actual arc fault, an AFCI indicator
may not trip every AFCI. AFCI indicators are provided with markings or instructions that state the following or equivalent: ‘‘CAUTION: AFCIs recognize characteristics unique to arcing, and AFCI indicators produce characteristics that mimic some forms of arcing. Therefore the indicator may provide a false indication that the AFCI is not functioning properly. If this occurs, recheck the operation of the AFCI using the test and reset buttons. The AFCI button test function will demonstrate proper operation.’’
These devices are not intended for use as comprehensive diagnostic instruments.

Take special note of the last sentence.