Determining Voltage of a Hubbellock Outlet

Palak · May 1, 2019

We have an older grinder with an integrated Hubbellock outlet built into it. The grinder runs off of 480V 3 phase, but it has a few outlets on it, including one that has a conventional 120V outlet. The Hubbellock outlets, at least from a few we have in the shop, appear to be able to handle from 240V through 600V.

What is the best and safest way to test the voltage of this outlet? The Hubbellock outlets don't seem to have a way to insert multimeter probes into them. We did plug an older 220V 3-phase pump into this outlet (naively assumed it was 220V), and the pump did run, but the casing got very hot after 5 mins and we shut it down (leading us to believe it might be wired at 440V).

Would appreciate any sage experience anyone could lend.

atomarc · May 1, 2019

Isn't there an electrical enclosure on the machine that has all the pertinent apparatus inside..things like step down transformers, buss bar, etc. There might even be a schematic glued to the inside of the door. This would tell you what to expect at the receptacle.

Stuart

sfriedberg · May 1, 2019

Take a spare Hubbelock plug with a properly connected wire tail, connect your multimeter to the wire tail, plug it in... You could even temporarily remove the plug from the motor you tested.

Palak · May 2, 2019

Thanks for the replies.

It's a very old Cincinnati grinder (circa 1940s I believe). I will check again, but I don't think there is a schematic, and these old grinders are frequently modified anyway.

Hmm. Exposed wiring at a potential 440V has me a little nervous. Would there be any chance of arcing this way? I've seen a few videos of 440/480V accidents, and it has me a little nervous of exposed wiring. Not saying it isn't a good approach, just has me nervous. So, you are suggesting disconnecting the cord from the pump, and plugging the cord in with the exposed 4 wires? One probe to a hot, and the other to the ground?

atomarc · May 2, 2019

From you last post it appears you're not comfortably knowledgeable with electricity. I would suggest you have an industrial electrician take a look at your machine.

Stuart

Froneck · May 2, 2019

Hubble and other brand lock plugs and sockets are made for a particular voltage (amperage too) so that wrong connection is avoided, that assumes that who ever wired the socket used the correct voltage configuration. If your worried about exposed wires then wire a plug that fits the configuration your using to the meter, you only need 2 wires. If you have the type probe than can be removed for the leads remove the probe and wire direct to the plug. If you have the molded probe wrap a wire around the probe and secure it with shrink tubing then connect the wire to the plug. If you don't have another plug remove the one you are using to make the test probe. Electric tape can also be used to insulate and secure the probe connection.

hitandmiss · May 2, 2019

Froneck said:
Hubble and other brand lock plugs and sockets are made for a particular voltage (amperage too) so that wrong connection is avoided, that assumes that who ever wired the socket used the correct voltage configuration. If your worried about exposed wires then wire a plug that fits the configuration your using to the meter, you only need 2 wires. If you have the type probe than can be removed for the leads remove the probe and wire direct to the plug. If you have the molded probe wrap a wire around the probe and secure it with shrink tubing then connect the wire to the plug. If you don't have another plug remove the one you are using to make the test probe. Electric tape can also be used to insulate and secure the probe connection.

The old ones (pre NEMA) were rated at 600 Volts and used for many voltages. Even some of the NEMA designations were changed over time.

To the OP, turn power off, make your connection and then turn the power on and take your reading. Reverse to unhook.

Bill

Froneck · May 2, 2019

I know the pre-NEMA were not made to limit connection to wrong voltage and amperage. Even if he did have NEMA rated socket there is no guarantee it's wired to it's configured rating! Turning off power in an industrial plant might create problems, who know what might be turned off. The easiest way is to make a test probe from the plug that fits the socket. I would thing that the machine has a box with a disconnect as it's required by OSHA but older machines might not or in a rather poor location. Getting properly connected is not the question here though the OP should look into it.
However since the OP is comfortable plugging in the machine, wiring a Volt meter in the same manner the machine was wired and plugged in will be a good way to test the voltage!

JST · May 2, 2019

As far as I know, plug caps and receptacles are made to a maximum voltage and current. End of story.

There are conventional uses for each, but you are free to use any type receptacle for any voltage within its ratings, so long as it is not used anywhere else in the facility for any OTHER voltage. I would not recommend using a receptacle that is conventionally used for a particular common voltage, like the usual 120V style, for some other voltage, but in general it is not forbidden.

The receptacles on the machine need to be measured to determine what they have been ised for. While it is a good bet that the "120V" outlet actually has that on it, I'd not advise assuming that until proven.

NONE of them may have their conventional voltages on them if, for instance, an internal transformer has not had the taps adjusted to the current mains voltage.

Tony Quiring · May 2, 2019

All that we have seen havr identifying markings for volts and amps.

Easy enough to just probe the holes with a voltmeter.

Most have a bent prong for safety ground.

Measure from each connection to each other connection as the a tual wiring can be anything.

By measuring all possibilities you will better understand it.

Sent from my SAMSUNG-SM-G930A using Tapatalk

Froneck · May 2, 2019

JST said:
As far as I know, plug caps and receptacles are made to a maximum voltage and current. End of story.
Not the case! Twistlock and other types are made with a voltage and amperage designation. The prongs are changed so as not to allow those without the same designation will not fit in another. For example a 4 wire 120V/208V 30 Amp plug will not fit a 120/208V 20 socket nor will it fit 120/208 30Amp 5 wire socket nor any other socket of a different designation. It's not a rating but rather a means to limit improper connection not maximum voltage and amperage rating. Some do overlap because there is just so many variations that can be made. The intent is to prevent someone plugging into a socket that has a different voltage or amperage designation

Usually I do put my volt meter probes in the socket but I do have a problem making connection. Probes have to be long and you have to "fish" to make connection.

SAF · May 2, 2019

Hubbellock wiring devices

Palak said:
We have an older grinder with an integrated Hubbellock outlet built into it. The grinder runs off of 480V 3 phase, but it has a few outlets on it, including one that has a conventional 120V outlet. The Hubbellock outlets, at least from a few we have in the shop, appear to be able to handle from 240V through 600V.

What is the best and safest way to test the voltage of this outlet? The Hubbellock outlets don't seem to have a way to insert multimeter probes into them. We did plug an older 220V 3-phase pump into this outlet (naively assumed it was 220V), and the pump did run, but the casing got very hot after 5 mins and we shut it down (leading us to believe it might be wired at 440V).

Would appreciate any sage experience anyone could lend.

So everyone is on the same page with HUBBELLOCK. He said its' old school type, well, the old ones were rated, 30A 600V AC, 20A 250V DC, 3-Pole 4-Wire Grounding, Non- NEMA, and were used for anything in between.

And looked like this:

We have a grinder, fed from 480V, a working 230V 3Φ pump starts and runs, from the machine outlet, but overheats quickly, and a 120V 3W outlet exists.

If you make a logical deduction, the outlet is likely 480V supplied, like the machine. We now know that a 230V motor is running from it, saturated and hot, a 208V motor wouldn't fare much differently. And a 120V 1Φ outlet, wouldn't think of starting a 3Φ pump.

So that likely leads us, to a 480V 3Φ 4W outlet, whatever it says on the flange or connector, old school or new.

The simple way to test is, to remove 2)#6 cover screws, pull out the receptacle a couple of inches, turn the power on, and put your test leads on the terminals. No need to fuss with the insulated, spring loaded shield.

On a different note. I learned something today, all this time, those headache producing, long, run on paragraph posts, by Froneck, I though were due to a broken keyboard, or a defective return key.

I couldn't believe my eyes tonight, I had to do a double take...Look at that... that return key started working again, there's a line space in that there post!!! My headache is starting to dissipate.

SAF Ω

SteveBausch · May 3, 2019

I’ve seen enough old pushmatic breakers and old hubbel twistlocks that don’t have a valid nema id to immediately determine to toss that crap and replace asap.

Palak · May 3, 2019

Thank you for the replies.

SAF, thank you for posting the pictures, and your astute analysis. Yes, that is what our plug and outlet look like, and yes, outlet/plug are rated for 30A 600V AC. Our plug actually has a metal cover, but other than that, just like the picture. Seems to be a good design for wet environments, as the connections are buried within the outlet, unlike more conventional plugs. SAF, your recommendation for testing, by withdrawing the plug cover, is a good one. One probe to hot and the other to ground?

Froneck, your recommendation appears to be a very safe one, and we may go that route, as we can do it somewhat remotely. We don't have any spare plugs in this configuration, so we will have to use the pump cord. Should we remove all but two of the wired connections at the plug, then disconnect the wiring at the pump, tape the multimeter probes to the two connected wires, and then turn on the power? One probe to hot, and the other to ground?

Thanks again to all the cognoscenti.

Froneck · May 3, 2019

I think you should remove all the wires. Not knowing what is connected to the plug the 2 wires you remove will become hot to ground thru the motor if connected direct. Mark the wires as removed, one of them is ground and you wouldn't want to reconnect it to a hot line. However if you chose the method described by SAF make sure you lock the disconnect off especially if it's not near the outlet! Use a padlock to insure someone can't turn it on!!

SAF the best way to tests the voltage by someone that is not comfortable doing it your advance way is to wire up a plug to a volt meter. BTW test plugs are also made. Those old outdated plugs were changed do to industrial accidents. An attempt was made to make outlets fit plugs so as to keep wrong voltage from being connected. My intent is to explain what I wrote so that those not familiar with preforming the task requested. Better to be long winded and safe than skimming over something and getting someone hurt. Sure turning off the power to remove the socket but it must be turned on to test it! That is if there is a nearby disconnect! Also quite often the length of connected wire is too short to make the test you describe! I've worked in places where the disconnect was in a large remote panel, turning off the wrong one will keep the outlet hot but also turning off something connected to a machine that's running can get someone hurt!

atomarc · May 3, 2019

In an effort to beat this horse to death I'll add this..again! The OP doesn't seem to be familiar with most aspects of electricity, and his posts allude to some type of work environment with more than one employee. Is there a competent electrician anywhere on site? For anyone even half savvy on electrical troubleshooting, this would have been a 5 minute job. This is being said out of concern for the OP's health and safety.

And..again I point out, there has to be some type of enclosure with at least one xformer in it if there is an obvious 120 volt outlet on the machine. Having said that, any other voltage than the supplied voltage to the machine, 480v-3phase, will have to be attached to some type of buss and some type of xformer in that enclosure. That's the place to test the voltage with a simple wiggy..no farking around with a weird outlet and wires taped together..!

Stuart

JST · May 3, 2019

Froneck said:
Not the case! Twistlock and other types are made with a voltage and amperage designation. The prongs are changed so as not to allow those without the same designation will not fit in another. For example a 4 wire 120V/208V 30 Amp plug will not fit a 120/208V 20 socket nor will it fit 120/208 30Amp 5 wire socket nor any other socket of a different designation. It's not a rating but rather a means to limit improper connection not maximum voltage and amperage rating. Some do overlap because there is just so many variations that can be made. The intent is to prevent someone plugging into a socket that has a different voltage or amperage designation

Usually I do put my volt meter probes in the socket but I do have a problem making connection. Probes have to be long and you have to "fish" to make connection.

You missed the point.....

There are "conventional uses" of several styles, but no rule that makes it possible only to use that style with a particular voltage. The rule is not to use the same type for more than one voltage in a facility..

That said, the "conventional use" may be so common that obvious types like the regular 120V are off limits, but there are so many special types that there is always one you do not use and which may be used for some odd purpose, as long as it is within the UL rating of the receptacle and plug cap.. You label the receptacle, of course.

Froneck · May 3, 2019

Granted nothing requires that proper connection to designated volt and amperage listing is adhered to, I'm guilty of it. I use one type in my shop for all amperage connections. But on machinery that is 480VAC I use a different type, I can make a mistake too and possibly plug into the wrong voltage. But I'm a one man shop so I know how the system is wired! NEMA ratings are not in question, the OP wants to measure the voltage at the socket at his facility and admitted he is unconformable working with open 480VAC. He has plugged in his pump into the outlet so he is comfortable making that connection! Making a simple same as connection to his meter is the best way for a novice to check the voltage at the existing plug! Disconnection is not a simple way. First he don't know where it might be, Second I would never assume that by using a disconnect the power in disconnected! I have seen a number of single phase disconnects connected to 3 phase as well as 2 pole contacters used on 3 phase. It's a fools suggestion for a novice to simply disconnect the supply then open the outlet box, re-power and make test connections! In a facility on any large type I would not trust my life on someone in the past using the correct type disconnect. If I were to use the disconnect as described I would make sure it was properly wired and that all 3 lines are disconnected! Furthermore I would lock it out so that some other idiot don't turn it back on!

Ziggy2 · May 3, 2019

Palak said:
Thank you for the replies.

SAF, thank you for posting the pictures, and your astute analysis. Yes, that is what our plug and outlet look like, and yes, outlet/plug are rated for 30A 600V AC. Our plug actually has a metal cover, but other than that, just like the picture. Seems to be a good design for wet environments, as the connections are buried within the outlet, unlike more conventional plugs. SAF, your recommendation for testing, by withdrawing the plug cover, is a good one. One probe to hot and the other to ground?

Froneck, your recommendation appears to be a very safe one, and we may go that route, as we can do it somewhat remotely. We don't have any spare plugs in this configuration, so we will have to use the pump cord. Should we remove all but two of the wired connections at the plug, then disconnect the wiring at the pump, tape the multimeter probes to the two connected wires, and then turn on the power? One probe to hot, and the other to ground?

Thanks again to all the cognoscenti.

It is a crap design and there is a good reason why they have fallen out of favor. They arc flash easily and are not suitable around moist environments.

JST · May 3, 2019

Froneck..... Yep, but it seemed that there was some assumption creeping in that a specific type would have a specific voltage. As a relative used to say, "You never can always sometimes tell what you least most expect" (I don't know where they got that)

The only way to know is to measure.

JST said:
As far as I know, plug caps and receptacles are made to a maximum voltage and current. End of story.

There are conventional uses for each, but you are free to use any type receptacle for any voltage within its ratings, so long as it is not used anywhere else in the facility for any OTHER voltage. I would not recommend using a receptacle that is conventionally used for a particular common voltage, like the usual 120V style, for some other voltage, but in general it is not forbidden.

The receptacles on the machine need to be measured to determine what they have been ised for. While it is a good bet that the "120V" outlet actually has that on it, I'd not advise assuming that until proven.

NONE of them may have their conventional voltages on them if, for instance, an internal transformer has not had the taps adjusted to the current mains voltage.

Determining Voltage of a Hubbellock Outlet

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