Multi meter and pedestal power

pianotuna wrote:
Yup,

And that is one of the several reasons I won't use such so called "protection".

spike99 wrote:
For "safe" voltage range readings, I use 102

Then please provide reliable and verifiable information on what numbers should be used instead of alluding to some "secret handshake" knowledge base that it seems only you might be a member of. The Dometic service manual from 2000 specifies that their ACs are 115V units and have a PROPER operating voltage of between 103 and 126.5V so if you have reliable and verifiable information that those numbers should not be used please provide the source for your information so all of us that believe the ENGINEERS that designed and company that warranties at least the Dometic line of ACs know more than us arm chair engineers can update our benchmarks. I don't have any documented information more recent than the 2000 SM so if someone has a specific document they can cite and hopefully give a link to so we can independently see what it says PLEASE DO.

One can PERSONALLY set any number they want, but when they imply that other lower numbers can/might/could/will cause issues or problems they are SIMPLY MISLEADING those looking for correct and accurate information and are doing IMO a HUGE DISSERVICE to the membership here. Even the engineers at Progressive that designed their EMS to protect such appliances as ACs have spec'd their units for a low/high voltage limits of 104/132. I admit there is some delta in the high end, but at least progressive's low voltage cut out meets Dometic's specification. I don't remember the specs for the SurgGuard, but think the low limit might be 102 which while outside Dometic's specs is only 1V off.

I submit that Dometic WOULD NOT specify a voltage that had even a remote probability of doing damage since that would open them up to unnecessary warranty liability and $$$. Thus I and others I think should be comfortable in taking that 103V figure spec'd by DOMETIC "TO THE BANK" so to speak and if they personally want to use a higher number as I said fine, but make sure they are clear in the number they are using is only a personal one and not one backed by any reliable and authoritative source.

For the O.P. I think you got your basic question answered, but I would like to caution you that simply doing what you propose is a fairly poor way of actually protecting you trailer from voltage issues specifically. Unless you intend to stare at a voltmeter 24/7 while hooked up voltages as CGs are know to vary and unless you have a system that automatically monitors them you are I submit providing almost no REAL PROTECTION since you are only looking an one voltage at one specific time and even then are not measuring it under a load, but open circuit. It's better than nothing, but just barely IMO in the overall scheme of things.

Larry

2oldman wrote:
This diagram might help:

30a socket wiring

I generally like 108v and above.

The main page of the site.

thanks, this was very helpful.

gmw photos wrote:
This will probably come off sounding snarky, and I do not intend it that way. But....if a person has to ask this question, I am not so sure they will even know how to safely check the power at the pedestal.

Just sayin'.....a guy poking metal objects into them there holes could very well electrocute themself.

Perhaps a better choice might be a TRC ( or similar ) surge guard.

I understand your concern. I test recepticles in house but didn't feel comfortable with 30 amp plugs, but they still are 120 volts. also understand the need for surge protection. thanks

kcmoedoe wrote:

oxygen wrote:
How does one use the meter to test 30 amp voltage? Which post is hot and which is neutral, looking straight at the pedestal? What would a safe low and high voltage reading be?
thanks

In answer to your questions, the left hand slot would be the Hot and the Right hand slot the neutral. Voltage should be 120 volts with the National Electric Code allowing a 5% variance which would be +/- 6 volts. Given the possible variance of a meter you can be pretty comfortable with a voltage between 112 volts and 128 volts. Anything higher or lower is probably going to be trouble, since voltage will vary slightly over time and you are probably not going to be testing at the absolute highest or lowest reading of the day.

Thanks for this answer. An earlier post with picture showed what you very plainly said. Thanks

I'll check polarity and ground before hooking up, but the no-load voltage at the pedestal doesn't mean much to me. I want to know what voltage I see at outlets inside the RV, with a load like the A/C. That's a better check of what the pedestal can provide, and the quality of the connections, which is more often a problem than the supply to the pedestal. Those pedestal sockets get abused, and often fail to make good connections.

Tennessee_Nomad wrote:

kcmoedoe wrote:
In answer to your questions, the left hand slot would be the Hot and the Right hand slot the neutral. Voltage should be 120 volts with the National Electric Code allowing a 5% variance which would be +/- 6 volts. Given the possible variance of a meter you can be pretty comfortable with a voltage between 112 volts and 128 volts. Anything higher or lower is probably going to be trouble, since voltage will vary slightly over time and you are probably not going to be testing at the absolute highest or lowest reading of the day.

Good information... A multi-meter is good for testing the "right now" voltage, but the only sure way to catch the dangerous drains or spikes is a good surge protector. I've never run into a bad pedestal, but it only takes once to mess up some really expensive equipment.

Exactly. Nothing wrong with checking with a meter. But what happens when the voltage spikes or drops after you set up. A good surge suppressor is designed to continuously monitor your incoming voltage.
Check with a meter will help you detect a pedestal that is broken, however it will not fully protect your RV.
Invest in a surge protector in you want full protection. No need to test pedestal each time. Install a Progressive hard wired surge guard and forget about it. The Progressive will do all the monitoring for you.

kcmoedoe wrote:
In answer to your questions, the left hand slot would be the Hot and the Right hand slot the neutral. Voltage should be 120 volts with the National Electric Code allowing a 5% variance which would be +/- 6 volts. Given the possible variance of a meter you can be pretty comfortable with a voltage between 112 volts and 128 volts. Anything higher or lower is probably going to be trouble, since voltage will vary slightly over time and you are probably not going to be testing at the absolute highest or lowest reading of the day.

Good information... A multi-meter is good for testing the "right now" voltage, but the only sure way to catch the dangerous drains or spikes is a good surge protector. I've never run into a bad pedestal, but it only takes once to mess up some really expensive equipment.

Yup,

And that is one of the several reasons I won't use such so called "protection".

spike99 wrote:
For "safe" voltage range readings, I use 102

kcmoedoe wrote:

oxygen wrote:
How does one use the meter to test 30 amp voltage? Which post is hot and which is neutral, looking straight at the pedestal? What would a safe low and high voltage reading be?
thanks

In answer to your questions, the left hand slot would be the Hot and the Right hand slot the neutral. Voltage should be 120 volts with the National Electric Code allowing a 5% variance which would be +/- 6 volts. Given the possible variance of a meter you can be pretty comfortable with a voltage between 112 volts and 128 volts. Anything higher or lower is probably going to be trouble, since voltage will vary slightly over time and you are probably not going to be testing at the absolute highest or lowest reading of the day.

Thank you for actually answering the question.

oxygen wrote:
How does one use the meter to test 30 amp voltage? Which post is hot and which is neutral, looking straight at the pedestal? What would a safe low and high voltage reading be?
thanks

In answer to your questions, the left hand slot would be the Hot and the Right hand slot the neutral. Voltage should be 120 volts with the National Electric Code allowing a 5% variance which would be +/- 6 volts. Given the possible variance of a meter you can be pretty comfortable with a voltage between 112 volts and 128 volts. Anything higher or lower is probably going to be trouble, since voltage will vary slightly over time and you are probably not going to be testing at the absolute highest or lowest reading of the day.