Voltage Disparity

chideock · 08-10-2016, 04:52 PM

At my son's place and plugged into 15amp receptacle. MH is 30amp. A 50ft 12gauge extension to the MH to an adapter to a short dongle into the MH. Voltage at house receptacle 115, voltage at MH end of extension 115, voltage through the adapter 115v. when plugged into MH my hardwired Progressive EMS says 109volts 3amp draw (fridge and converter only items on). I then checked with a voltmeter an AC receptacle at the front of the MH (other end of the MH from the EMS) and that receptacle shows voltage at 113volts.

So the voltage into the MH is 115, the EMS says 109 but a receptacle in the MH says 113. I am scratching my head - does my EMS readout have a problem?

Will contact Progressive in the next couple of days and talk to them.

fonzie · 08-10-2016, 04:56 PM

So either your EMS is off or your meter is off.....I put my money on your meter....

chideock · 08-10-2016, 05:14 PM

Good thought. My meter is a good quality expensive digital meter. I dont think it would be the meter.

davel1971 · 08-10-2016, 05:21 PM

Im assuming your getting the 115 off the end of the cord with no load? A minimal drop with a load would be normal, such as the 113 your reading on an inside outlet. Open the cover on your EMS and read right from the connections and see what you have

chideock · 08-10-2016, 05:44 PM

Yes the readings are no load except the hardwired ems is loaded with fridge and converter.

I forgot to mention that the house receptacle and extension/adapter readings were from my portable trc ems that i haveleft over from last motorhome. The mh receptacle reading was done with the digital meter. The hartwired ems is a progressive.

Once I did readings outside with portable ems I removed it from the feeding extension cord and adapter.

davel1971 · 08-10-2016, 05:48 PM

in that case, too many variables to be concerned over a couple volt difference

chideock · 08-10-2016, 06:01 PM

The other suggestion of taking readings right off the hardwired ems is great. Had not thought of that step.

Have to wait now a couple of days to get that done. Let you know what i find.

chideock · 08-10-2016, 06:05 PM

Quote:

Originally Posted by davel1971

in that case, too many variables to be concerned over a couple volt difference

Sort of. I got started on this because the hardwired ems had dropped to 104 volts and shutdown the power. So i started taking readings. Its not much of a drop from 109 to 104.

I guess i am wondering if i might hav a faulty progressive hardwired ems.

davel1971 · 08-10-2016, 06:15 PM

the long cord will give a drop with a load.

chideock · 08-10-2016, 06:38 PM

Quote:

Originally Posted by davel1971

the long cord will give a drop with a load.

True. Maybe thats my answer. Just the recetacle reading in the mh from the digital meter showed 113 while the hardwired ems was showing 109.
I guess I need to open up the hardwired ems and take readings there to get a better understanding.

Have to do this at home hooked up to my 30 amp supply and see what I get.

davel1971 · 08-10-2016, 07:50 PM

Quote:

Originally Posted by chideock

True. Maybe thats my answer. Just the recetacle reading in the mh from the digital meter showed 113 while the hardwired ems was showing 109.
I guess I need to open up the hardwired ems and take readings there to get a better understanding.

Have to do this at home hooked up to my 30 amp supply and see what I get.

Yep, you might be worried about nothing. But it's good you understand enough to know there is something different.

**Bama Rambler** · 08-11-2016, 08:45 AM

Just to flatten the playing field, I'd hook all those measuring devices you have to as close to a common place as I could and see what they read.

It wouldn't surprise me if they were all off a little.
What is the brand of multimeter you have?

clr · 08-11-2016, 09:04 AM

You will need to have the same load on the circuit when you take all of the measurements. When you have no load the voltage will be higher. As the load increases and the drop across the extension cord and other items increases the voltage will drop. Since you measured the house outlet with no load it would measure higher voltage. So I do not think you have a problem here other then the low voltage to the RV. Your EMS is just doing its job and protecting you from low voltage than may harm your AC or other electronics in the RV. I would not run AC items with a voltage below 110V but that is not the setting of the EMS.

chideock · 08-12-2016, 10:36 AM

Quote:

Originally Posted by davel1971

Yep, you might be worried about nothing. But it's good you understand enough to know there is something different.

More than likely I am concerned about nothing.

Left Son's place yesterday early morning. When I looked at the EMS reading it was 114volts and no errors. When we got home yesterday I hooked up to my 30amp. Reading of the EMS was 121.

Today I am showing 122 from the EMS. All looks good.

So, really no problem. This does show me that a 12gauge extension cord really does not provide the consistent good quality power that one would want in there MH. Also it has proven to me that an EMS is really an essential item for your RV investment.

Thanks all for the suggestions and comments

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