Progressive industries EMS -Pt50X

[GlennWest]

Looking at the display it shows I only using 5 amp and 7 amp on the legs. It is overcast today but is still hot and humid. Both mini splits running. Reackon that accurate?

[Cowdog353]

Depends,. What else is online? Fridge, TV, Hot water heater, battery charger?  If none of them on, could be possible. Try turning TV  hot water heater or maybe a toaster.The last two should show 8-10 amp additional draws each. 

Good Luck, Jim

[GlennWest]

Won't much on. Water heater gas. Residential fridge. TV was off. Chromebook charging. Both mini splits on and 70 degrees inside. 89 and very humid outside. I was just surprised at that. Now the park here says we use less than anyone else. Going to start keeping an eye on it. Might give me a good reference for inverters

Edited August 25, 2020 by GlennWest

[jcussen]

Wonder if your unit only reads each leg to neutral. Not sure how it reads leg to leg in a 240 volt application. Might give PI a call.

Edited August 25, 2020 by jcussen

[GlennWest]

2 minutes ago, jcussen said:

Wonder if your unit only reads each leg to neutral. Not sure how it reads leg to leg in a 240 volt application. Might give PI a call.

It shows voltage and amps on each leg. Assume 240v draw would show on both legs since it pulls from both legs.

[jcussen]

11 minutes ago, GlennWest said:

It shows voltage and amps on each leg. Assume 240v draw would show on both legs since it pulls from both legs.

Over my head, but on my coach, CT's are on each leg and neutral. So will read current flow on each leg between that leg and neutral, seeing you are not using neutral at all, for 240 volts, no actual current on the neutral wire except for the 120 volt leg to neutral wire loads. Maybe John will explain how it really works.

[Kirk W]

3 hours ago, jcussen said:

Wonder if your unit only reads each leg to neutral. Not sure how it reads leg to leg in a 240 volt application.

If that were the case, what it would measure is the difference between the currents in the two legs, or in this case it wold read 2 a. With an exactly balanced load, the very same amps travel in via one leg and out via the other(in theory as AC doesn't really do anything but move backward and forward). 

I must admit that I never gave that any thought, since the ones that I have owned didn't show remotely and I never paid it much attention. With exactly the same current load on each leg you would see 0a on the neutral leg, so it must somehow measure from L1 & L2 to neutral, or ground,....

Now there is some real food for thought. 

[GlennWest]

Been outside a lot today and look everytime I went by it> DW been washing and drying today. That's over mostly now because they just turned water off here. We pulling out in a few hours. Saw as high as 19 amps on L1 and 8 amps on L2. So it seems to be accurate. Think when we get ot our destionation and turn on acs will look at it and see what going on.

[jcussen]

22 minutes ago, Kirk W said:

If that were the case, what it would measure is the difference between the currents in the two legs, or in this case it wold read 2 a. With an exactly balanced load, the very same amps travel in via one leg and out via the other(in theory as AC doesn't really do anything but move backward and forward). 

I must admit that I never gave that any thought, since the ones that I have owned didn't show remotely and I never paid it much attention. With exactly the same current load on each leg you would see 0a on the neutral leg, so it must somehow measure from L1 & L2 to neutral, or ground,....

Now there is some real food for thought. 

Pretty sure it does not travel in one leg and out the other. My surge gard reads one leg to neutral. If one leg is pulling  120 volts at 10 amps, meter is reading 10 amps on that leg. If other 120 volt leg is pulling the same 10 amps, it reads 10 amps on that leg. My confusion results from how it reads a strictly 240 volt load that does not use neutral at all, know it can be done, had a Newell that read both legs, and total amp draw because it had 240 volt appliances. Guessing it could read current in strictly 220 volt loads, and splits it between the two leg readings, but just a guess,  Hopefully an expert will chime in.

[Kirk W]

13 hours ago, jcussen said:

Pretty sure it does not travel in one leg and out the other.

Take a look at the wire sizes on your power cord. You will find that in a 50a RV cord the neutral is much smaller than L1 & L2 and the reason is that only the current difference between the two sources is ever on the neutral. If the load is exactly the same on L1 as it is on L2, there will be no current flow through the neutral at all. It is a principle from basic electrical school, I attended way back in 1961.  😊

Edited August 26, 2020 by Kirk W

[oldjohnt]

1 hour ago, Kirk W said:

Take a look at the wire sizes on your power cord. You will find that in a 50a RV cord the neutral is much smaller than L1 & L2 and the reason is that only the current difference between the two sources is ever on the neutral

Yo Kirk, With all due respect, I must disagree with that statement. Its my experience and opinion in a 50 amp RV Power Cord ALL THREE "CURRENT CONDUCTORS, L1,L2, AND NEUTRAL ARE THE SAME SIZE !!!!!!!!!! I can envision the 4th wire, the Safety Equipment GroundING Conductor (bare/green) being smaller, but NOT the Neutral for the reasons I describe below in paragraph 6. Let me know what you think, I always enjoy and appreciate sparky chatting with you and your help. Hey if I'm wrong on this it wont be the first time lol If so  apologize as I'm rusty having been retired from power distribution design for yearssssssss and codes and things change  ...

I THINK NEUTRAL MUST BE AT LEAST SAME AS L1 OR L2 NOT SMALER     No Warranty however, you may well be correct !!!

 

I don't have any EMS schematics but I can provide some basic info, here goes:

1) A current transformer (just a coil of wire encircling a conductor) can measure the current flow in a conductor, but that's NOT with respect to any other conductor, merely the flow of electrons IE Current IN THAT CONDUCTOR. So its possible to measure current flow in L1 or L2 no problem.

2) A true 240 volt ONLY load (IE NO 120 loads, NO Neutral) does NOT rely on or is even connected to Neutral, just two Hots L1 & L2 with 240 VAC Line to Line.

3) In a 120/240 Volt Single Phase Three Wire system there's 120 VAC L1 ORRRRRRRR L2 with respect to Neutral and as above 240 VAC Line to Line..........

4)  If there are two 120 VAC Loads, and each drew the same current, THE NEUTRAL CURRENT WOULD BE ZERO.

5) If there is ONLY  say a 10 amp load on L1 and nothing is attached to L2,, NEUTRAL CURRENT WOULD BE 10 AMPS..  

6) The Neutral Conductor must have sufficient ampacity to carry the maximum current in either L1 or L2 alone including  the worst case condition when there is say 50 amps on L1 and ZERO on L2 in a 50 amp RV. IE if the L1 (or L2 ) conductor is rated for 50 amps (6 Gauge) and its possible to return that same 50 amps  via the common Neutral (nothing on L2) the Neutral must also be 6 Gauge NOT SMALLER 

John T

[mptjelgin]

52 minutes ago, oldjohnt said:

Yo Kirk, With all due respect, I must disagree with that statement. Its my experience and opinion in a 50 amp RV Power Cord ALL THREE "CURRENT CONDUCTORS, L1,L2, AND NEUTRAL ARE THE SAME SIZE !!!!!!!!!!

Absolutely correct.  The three conductors must be the same size as the neutral can carry the same load (50 amps) as either of the hot legs. I have wired a couple of 50 volt outlets at National Wildlife Refuges and the code requirements are crystal clear. All three legs must be sized for 50 amps. In my experience even the safety ground has been the same gauge, but I'm not certain if that was a code requirement or not. 

Edit - Looks like the CAMCO 50 amp extension cord does drop the wire gauge for the safety ground, but for the reasons stated above not for the neutral:

"High Conductivity with a Flexible and Sleek Design: Bendable extension cord adapter allows easy conversion from a standard 50 Amp male to 50 Amp female. Rated for 50 Amp 125 Volts. Constructed with  6/3 + 8/1  gauge wires for superior conductivity."

Edited August 26, 2020 by mptjelgin

[jcussen]

Just talked to Progressive Industries tech support. Tech thinks that a 240 volt load will read equal amps on each leg, so if AC draws 20 amps at 240 volts, surge protector readout will show 10 on each leg. When Glen gets situated, he can prove this theory out.

Edited August 26, 2020 by jcussen

[Kirk W]

8 minutes ago, mptjelgin said:

The three conductors must be the same size as the neutral can carry the same load (50 amps) as either of the hot legs.

Actually, I said it wrong as I should have said that if it were to carry all of the current from both L1 & L2, it would need to be twice the size of the other two, which it is not. If L1 carries 50a and L2 carries 50a and both left via the neutral, it would be carrying 100a, which it isn't sized for. Sorry about the miswording, as I knew what I intended to say. 

16 hours ago, jcussen said:

Pretty sure it does not travel in one leg and out the other.

This was the statement that I so poorly replied to.  🙃

[oldjohnt]

2 hours ago, Kirk W said:

If L1 carries 50a and L2 carries 50a and both left via the neutral, it would be carrying 100a, which it isn't sized for. Sorry about the miswording, as I knew what I intended to say. 

Kirk, 1) In a 120/240 Volt Single Phase Three Wire Common Neutral service (like to a home and most RV parks) if L1 carried 50 amps and L2 carried 50 amps

                                         NEUTRAL CURRENT WOULD BE   ZERO    NOTTTTTTTTTTTT 100 AMPS   

         2) If L1 carried 50 amps and L2 zero amps 

                                         NEUTRAL CURRENT WOULD BE 50 AMPS again NOT 100

         3) There is A COMMON  NEUTRAL CONDUCTOR USED in a typical 120/240 Volt Single Phase Three Wire Service, and the very reason why it has to be as large as but NOT smaller (as you described above) then the hot phase conductors is because it may have to carry ALL the current of one leg (which is 50 amps in a 50 amp RV circuit protected by a 50 amp breaker) HOWEVER it never has to carry the 100 amps you mention because, once more, if BOTH legs carry 50 amps NEUTRAL WOULD BE ZERO AMPS.

 Hey not to worry, everyone can make a mistake or misword lol, Ive done it many many times and will likely do it again grrrrrrrrrrrr As  far as I'm concerned anyone who has NEVER made a mistake or misworded something must never have done anything lol 

 Maybe some of the other electricians or sparkies can explain it better then me, I'm rusty on this stuff but believe the above still remains true if BOTH legs L1 & L2 in a 120/240 Volt Single Phase Three Wire service carried 50 amps, NEUTRAL CURRENT WOULD BE ZERO NOT 100 AMPS  

NOTE I don't think the Neutral Conductor in a 50 Amp RV Cord, needs to be TWICE THE SIZE OR 100 AMP RATED (even if BOTH legs draw 50 amps) but I do think it has to be at least the same size as the two hot phase conductors NEVER SMALLER   IE in a 50 amp RV power cord that's three No 6 conductors (plus the Equipment Ground) 

Hope this helps, post back any questions

Best wishes now, take care Kirk and thanks for all your help

John T

 

2 hours ago, mptjelgin said:

Absolutely correct.  The three conductors must be the same size as the neutral can carry the same load (50 amps) as either of the hot legs. I have wired a couple of 50 volt outlets at National Wildlife Refuges and the code requirements are crystal clear. All three legs must be sized for 50 amps. In my experience even the safety ground has been the same gauge, but I'm not certain if that was a code requirement or not. 

Edit - Looks like the CAMCO 50 amp extension cord does drop the wire gauge for the safety ground, but for the reasons stated above not for the neutral:

"High Conductivity with a Flexible and Sleek Design: Bendable extension cord adapter allows easy conversion from a standard 50 Amp male to 50 Amp female. Rated for 50 Amp 125 Volts. Constructed with  6/3 + 8/1  gauge wires for superior conductivity."

mpt, That's been my training and experience and what I have observed in 49 years of RV ownership and sales. Codes may change time to time but as far as I know the Neutral is at least the same size as BUT NOT SMALLER then the hot phase conductors. If were BOTH wrong hopefully someone can correct us as I'm never too old to learn

Pleasure sparky chatting with all of you, best wishes and God Bless 

John T  

Edited August 26, 2020 by oldjohnt

[oldjohnt]

2 hours ago, mptjelgin said:

Edit - Looks like the CAMCO 50 amp extension cord does drop the wire gauge for the safety ground, but for the reasons stated above not for the neutral:

"High Conductivity with a Flexible and Sleek Design: Bendable extension cord adapter allows easy conversion from a standard 50 Amp male to 50 Amp female. Rated for 50 Amp 125 Volts. Constructed with  6/3 + 8/1  gauge wires for superior conductivity."

 Yo mptjelgin, Best I recall  NO WARRANTY when I practiced power distribution, studied the NEC and attended regular NEC Seminars, there were certain and limited EXCEPTIONS and regarding possible smaller Equipment GroundiNG Conductor de ratings, the reasoning was it ONLY conducts Fault Current (Never full time normal return current), can be for limited time, and considering the response and trip time curves for a thermal magnetic circuit breaker HEY IT WILL STILL TRIP NO PROBLEM AND CLEAR THE FAULT with no damage to the slightly smaller equipment GroundiNG Conductor  THUS THE PERMISSIBLE DE RATIGN OF CONDUCTOR AMPACITY... IE its NOT sitting there constantly conducting full normal return current, but ONLY fault current and possibly for short time...   

Again codes may change and that was true longggggggggg  ago but I think that's how and why the Equipment GroundING Conductor could be de rated (NO 8 versus 6)  yet still code compliant 

Best wishes and God Bless, yall keep safe now

John T

[oldjohnt]

2 hours ago, jcussen said:

Just talked to Progressive Industries tech support. Tech thinks that a 240 volt load will read equal amps on each leg, so if AC draws 20 amps at 240 volts, surge protector readout will show 10 on each leg

jc, I cant speak for tech support but will offer these comments HOWEVER DO AS THEY SAY NOT ME

If a pure 240 only volt appliance that uses NO 120 and NO Neutral if there are NO faults,  OBVIOUSLY the current is the same on the two legs that supply it with 240 volts across L1 & L2. One of Kirchoffs laws if I recall ???

If in a 50 amp RV that supplies one 120 VAC AC on L1,,,,,,,, and another 120 VAC AC on L2,,,,,,, the current on L1 is whatever AC1 draws and the current on L2 is whatever current AC2 draws   DUH you say lol They  may or may not be the same, different size AC's can draw different current..........

HOWEVER if L1AC draws 12 amps (Meter will show 12 amps on L1) and L2AC draws 10 amps ,,,,,,,, NEUTRAL CURRENT WOULD BE TWO AMPS 

 Hey Im rusty on this maybe other engineers and electricians can correct me if I'm wrong, I'm never too old to learn and still enjoy doing so

John T 

[jcussen]

48 minutes ago, oldjohnt said:

jc, I cant speak for tech support but will offer these comments HOWEVER DO AS THEY SAY NOT ME

If a pure 240 only volt appliance that uses NO 120 and NO Neutral if there are NO faults,  OBVIOUSLY the current is the same on the two legs that supply it with 240 volts across L1 & L2. One of Kirchoffs laws if I recall ???

If in a 50 amp RV that supplies one 120 VAC AC on L1,,,,,,,, and another 120 VAC AC on L2,,,,,,, the current on L1 is whatever AC1 draws and the current on L2 is whatever current AC2 draws   DUH you say lol They  may or may not be the same, different size AC's can draw different current..........

HOWEVER if L1AC draws 12 amps (Meter will show 12 amps on L1) and L2AC draws 10 amps ,,,,,,,, NEUTRAL CURRENT WOULD BE TWO AMPS 

 Hey Im rusty on this maybe other engineers and electricians can correct me if I'm wrong, I'm never too old to learn and still enjoy doing so

John T 

Agree John,  hopefully when Glen sets up again, he will read each leg with only 240 volt ac loads, and then adding 120 volt loads to each leg. This should give him a pretty good idea if the tech is right.

Will be good info for anyone thinking of adding 240 volt appliances to their coach or trailer and use a EMS with a meter.

 

 

[Kirk W]

19 hours ago, oldjohnt said:

Kirk, 1) In a 120/240 Volt Single Phase Three Wire Common Neutral service (like to a home and most RV parks) if L1 carried 50 amps and L2 carried 50 amps

                                         NEUTRAL CURRENT WOULD BE   ZERO    NOTTTTTTTTTTTT 100 AMPS 

If you read my post, that is exactly what I told him. My point was that if the current did not pass from L1 to L2, then neutral would have to carry 100A, which it never does. It only reaches 50a if one leg is not in use for anything.   🙄

Edited August 27, 2020 by Kirk W

[oldjohnt]

5 hours ago, Kirk W said:

It only reaches 50a if one leg is not in use for anything

Congratulations Kirk, you and I I agree 100%    YOU GOT IT !!!!!!!!!!!!!

A) If one leg carries 50 amps and the other nothing, Neutral "only reaches 50a"    YOU ARE ABSOLUTELY CORRECT  

If BOTH L1 and L2 carried 50 amps NEUTRAL CURRENT IS ZERO its NOT 100  Amps !!!!!!!!!!

Additionally and related, I bet you understand why the Neutral Conductor in a 50 Amp RV power cord IS THE SAME SIZE AS THE HOT L1 AND L2 PHASE CONDUCTORS and NOT as you stated above

                 " You will find that in a 50a RV cord the neutral is much smaller than L1 & L2"  

The reason being if only one leg L1 carries the full 50 amps and there's no current in L2, THE NEUTRAL HAS TO CARRY THE ENTIRE 50 AMPS so it can NOT be "much smaller" as you indicated. 

 I certainly appreciate the help you have given myself and others.

Best wishes and God Bless, hope you don't get too much rain where you're located there in Texas. It would be a pleasure to visit you when I'm down your way headed to Austin in my RV and we can talk shop. You  be there in early to mid November ???? I will be  at SKP in Livingston Texas around that time, come on down for a cook out, you're always welcome...

John T

Edited August 27, 2020 by oldjohnt

[oldjohnt]

On 8/25/2020 at 7:55 PM, GlennWest said:

Think when we get ot our destionation and turn on acs will look at it and see what going on.

Glenn, when you get there and all set up let us know what you find. If a person with a 50 amp RV had one 120 VAC AC on L1 pulling different current then another 120 VAC AC on L2, say one draws 10 amps and another 12, the Neutral would see 2 amps. If an AC' is pure 240 Volt only, then of course unless there's a fault, L1 and L2 would be the same. If at the same time you have some 120 VAC appliances operating that will change currents. Also, with different AC's running one may be in fan mode while the others compressor is running. JUST SEVERAL VARIABLES AND UNKNOWNS to make an accurate prediction...

Keep safe all you Texas or Louisiana and nearby folks !!!!!!!!!!!!

John T

 

[Kirk W]

23 hours ago, oldjohnt said:

Congratulations Kirk, you and I I agree 100%    YOU GOT IT !!!!!!!!!!!!!

Perhaps a tech with 40+ years of experience does know a few things without an engineering degree?  🤔

[oldjohnt]

6 hours ago, Kirk W said:

Perhaps a tech with 40+ years of experience does know a few things without an engineering degree? 

YOU CERTAINLY DO KIRK, Its hard to beat experience, similar I learned MORE practicing as an engineer then I did back in school, more about RV's based on 49 years of ownership and sales then any instruction I ever had, and more about law after practicing it then I did in law school. The School of Hard Knocks right ???? HOWEVER the education provided me with basic engineering concepts so I was better equipped to put that to work out in the real world. The combination of BOTH education PLUS experience is the absolute best in my opinion, at least it was in my career. I worked hard for my education and that's something I'm proud of and can never be taken away from me. One should take pride in their occupation regardless of what it was (yours as a technician me as an engineer) I sure am.

Its always fun chatting with you even if were off topic and bore the others lol.

 I hope you didn't get too much rain your way and hopefully we can meet up someday somewhere in Texas ?????

Best wishes

John T

Edited August 28, 2020 by oldjohnt

[GlennWest]

Just came from outside. Took readings. It is 83 degrees now. DW has clothes dryer going. Both mini splits. Chromebook charging. No TV. L1 ranges 5-10. L2 ranges 19-23. Assume dryer on L2. These we average over 10 cycles. Will check again when dryer is finished. This is very informative.

Edited August 30, 2020 by GlennWest

[GlennWest]

Took reading after dryer stopped. TV and DVD playing. Temperature is 84. Both mini splits. Chromebook charging. We do have led DC lights on in living room. So converter is working. So L1 is low of 7, high of 11. L2 is 8 to 14. 15 cycles on unit display

Edited August 30, 2020 by GlennWest