| Author | Message | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1180 Registered: 10-2003 Posted From: 70.3.44.20 Rating: N/A |
An unanticipated BIG benefit of a 50A System... I don't use that much power when on the PP. So far there have been very few times that I really needed more than 30A in day-to-day operations, with a little load management. When I did the distribution, I was thinking of an eventual generator and the need to balance the legs as much as you could. I don't have a generator yet. So I'm connected to the CG's 50A service and for the last month or so I've been noticing the AC/HP fan speed fluctuating, sometimes horrifyingly low. I *knew* that meant problems somewhere, (probably not with the unit itself, but with the supply) but was too busy with other things to look into it. It happened maybe four times a day. I did connect a meter to an outlet to monitor from time to time. So Friday, some very strange things started happening electrically - power would drop to 90v or so and items in the coach would start to complain loudly. Then it went down to 70v, and loud pops accompanied the not-so-sweet smell of burning insulation and transformers. (I had placed the fire extinguisher close at hand as a precaution earlier) After a freakin mad dash outside to yank the power hose I began to try to understand what was going on.... then I realized that this strangeness all started when the neighbors began using their electric heaters. I began to really understand when things got much worse within the last few days with the addition of a new neighbor. Being surrounded by 5ers and Class C's, they were all on 30A service, which was all coming from the same leg, all down the line. I pulled my distribution panel's cover and the difference in voltage between the two legs was 20+ volts!!! It then became clear that L1 was way overburdened. (old wiring in the CG) So after thinkin' about it, I moved almost all of my breakers to L2, and with some easy power management, I now have the luxury of ample power while the other suckers are about to burn down their rigs and they don't even know it!  And you can bet I'm monitoring it closely. I'll be telling the CG Mgt. my discoveries, but I'll bet no changes will be made. Moved up in my project list will be panel gauges for both volts and amps from each leg of the distribution panel. I lost a microwave oven, a network router and a 'surge protector' power strip. I'm not absolutely positive that it all came from just the brownout, there may have been a big spike at the same instant? In any case those all fried in a matter of two or three seconds. I might also be considering one of them fancy autoformer things. Just a little tale for a Sunday morn... | ||
| James Robinson (Jjrbus)
Registered Member Username: Jjrbus Post Number: 107 Registered: 12-2000 Posted From: 70.10.212.199 Rating: N/A |
Great catch!!!!! It would be in your best interest not to mention this until you are ready to leave the campground. | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 249 Registered: 1-2005 Posted From: 67.126.86.142 Rating: N/A |
If the CG is not full, I would check the voltage on both legs at other sites. If better voltage, I'd request a move pronto before you lose something else. If the whole CG is bad, I would move to another CG. You've already lost three devices. The GC mgt will get the same low ball electrician to fix it that originally caused the problem. The next time he may get L2 onto safety ground, then your coach skin will be hot. I've seen it happen. | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 250 Registered: 1-2005 Posted From: 67.126.86.142 Rating: N/A |
What is the name and location of the CG? | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1181 Registered: 10-2003 Posted From: 70.3.44.20 Rating: N/A |
Yea, I think I'll stealthily slink around with the meter and see what I find. I'd rather not mention the CG name here, because the mgt. are very good folks, (even if the owner is a tightwad) and it's a place that's working well for me during ongoing bus-work, which one can't do at a lot of places. So, that post wasn't trying to rag on the CG, but just something else that one might have in their toolbox if they run up against insufficient power delivery. I will be paying close attention going forward and unplugging things when leaving for awhile until I get the 'feel' of this new arrangement. But if some research turns out it's really bad, I'll definitely make other arrangements. Thanks for the caution. If you really want to know, send me an email and I'll tell ya. (Message edited by chucks on December 16, 2007) | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 14 Registered: 11-2007 Posted From: 124.187.96.130 Rating: N/A |
I wouldn't have thought that low voltage would fry any of those three items - especially not a power strip or router. Sure you haven't got a missing neutral (centre leg or whatever you call it) somewhere that is causing 240V to get to your appliances | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1182 Registered: 10-2003 Posted From: 70.3.44.20 Rating: N/A |
Well Tony, I checked at the time and both neutral and ground were correct, but maybe it was possible that somehow upstream of my rig something like that happened? If even for a moment? I do know that when the voltage drops, the amperage goes up, so my guess was that when it dropped significantly, and current went *way* up and that's what caused the damage? Right now, leg 1 is 111v and leg 2 is 124 volts, with no significant loads of mine having any affect on that. Wonder what the minimum acceptable voltage is? Can't be much lower than 110. Experts, what say you? Ooops, L1 just went down to (Message edited by chucks on December 16, 2007) | ||
| Arnie Molloy (Ayjay)
Registered Member Username: Ayjay Post Number: 90 Registered: 10-2005 Posted From: 141.154.32.138 Rating: N/A |
Hi Chuck and others interested. All depends on the park services: I bought a 50 to 30 amp adapter hard wired to L1. I bought a 50 Amp plug (male) and a 30 amp jack (female) and wired it just opposite to the adapter I have.(L2). This way I can use whichever leg has the highest voltage without any rewiring, just change adapters. This only works if I use the 30 to 50 adapter that I use when only 30 A is available...Confused?? AyJay | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 699 Registered: 12-2000 Posted From: 76.3.169.171 Rating: N/A |
We have an EMS (Energy Management Systems) monitor we purchased from John Palmer. It monitors volts, amps and frequency on each leg (we have the 50 amp model). If voltage drops below 110 or goes above 130, it instantly shuts off our system. Only had it do that once and that was because the voltage was 132. It also will shut down for frequency out of range, but I don't remember the parameters. Jack | ||
| Moe Hollow (Moehollow)
Registered Member Username: Moehollow Post Number: 8 Registered: 12-2007 Posted From: 68.183.235.70 Rating: N/A |
Ayjay, Let me guess. You adapt down from 50 to 30 using whichever adapter gives you the better leg. Then you adapt up to the 50 which distributes to both legs of your panel. If that's not it, it still would make sense. | ||
| Ed Jewett (Kristinsgrandpa)
Registered Member Username: Kristinsgrandpa Post Number: 356 Registered: 2-2003 Posted From: 64.24.208.24 Rating: N/A |
Chuck Newman, It may not have been the low ball electrician but instead the low ball design engineer that caused the problem since it is definitely a design problem. Also probably compounded by a lack of enforcement of the National Electric Code. Ed | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 320 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Chucks, The campground has two problems. The neutral is called a neutral because "IT DOESN'T TAKE SIDES." Explained another way, the neutral only carries unbalanced current. Say one leg is drawing 35 amps, and the other is drawing 30 amps, there will only be 5 amps in the neutral. In this situation, a whole lot of current is being drawn on the low voltage side, and there is too much resistance (impedance) in the campground neutral, so the line to neutral voltage on the low current side goes high. If a neutral goes completely open, the low voltage side, (high current) will be exactly the same voltage below 120 as the high voltage side (low current) is above 120. Granted, on MOTOR loads only, (resistance devices just put out less heat) lower voltage means higher current draw, but the damage was probably done by the high side. Tony has the correct guess, the neutral isn't completely broken, the park is just WAY out of balance. The solution is for the campground to balance its line to neutral loads by moving half of the 30 amp services to the other leg. Minimum acceptable voltage drop is 5%, or 114 Volts continuous. Most utilities, will say that it has to be under for a minute, (at the main panel) before they will take action. George | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 251 Registered: 1-2005 Posted From: 67.126.86.142 Rating: N/A |
Ed, I agree with you except unless it's a really big CG (or other big commercial project) an electrical contractor usually does the system design, at least in Calif. I've seen more than one job that had a handyman "fix" the electrics because of economics. Then when he crosses wires and blows equipment (happened this summer to a friend), folks naturally get upset and question the motives of the CG owner. And you are right about abuses of NEC. It happens every day. George, what you say is correct. And as you pointed out, higher current draw with sagging voltage occurs only with inductive loads. Chuck lost three electronic devices, and I agree probably not due to low voltage. You certainly don't blow a suppressor strip with low voltage. Something is causing transient voltage events. Their may be more than one problem brewing in the CG system. Hopefully the entire CG is not unbalanced to the extent he is seeing, and if it advantageous for him to stay there, some checking and possible site move may be in order to save his other devices. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 137 Registered: 10-2006 Posted From: 66.90.229.126 Rating: N/A |
Wait for the summer!! Your friendly neighbors will be plugged in with step up transformers , to keep the voltage to their air cond up! Same watts , but the amps rise as the voltage leaves. FF | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1183 Registered: 10-2003 Posted From: 68.240.14.23 Rating: N/A |
Boy, you gentlemen continue to amaze. It is such an interesting journey we're all on and every time I come to the board I learn something. I had completely forgotten the difference between inductive vs. resistive loads in regard to their characteristics under voltage drop. I forget a lot!  It is good to know the acceptable drop is 5%. Heck I should have looked it up, as I have da NEC books. Bottom line, my assumption as I begin to explore this, is that, as George said, "The solution is for the campground to balance its line to neutral loads by moving half of the 30 amp services to the other leg." Thank you, as always, for sharing your knowledge and thoughts. | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1184 Registered: 10-2003 Posted From: 68.240.14.23 Rating: N/A |
Oh, and Fast Fred, they can't afford step-up transformers. ;) But I won't be here that long anyway! | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 15 Registered: 11-2007 Posted From: 60.229.34.218 Rating: N/A |
5% is the supply authority figures, but it would be a very irresponsible appliance manufacturer that would design stuff to fail at 6% variation. 10% should be easily handled and even more like 20% before it is actually damaged. In the big cities, the voltage is quite stable, but those on the end of long lines in rural areas, especially if it also feeds a saw mill or other industrial user, can expect 10% variations on a daily basis. I mentioned the faulty neutral as a possibility (and I'm not up with exactly how your electrics are arranged, eg whether you have a neutral-earth connection in your RV) because if the neutral to your RV is missing and you have 220v connected and there are two loads switched on- one low impedance load on L1 - say a strip heater or coffee maker (both low value resistive) and a high impedance load on L2 - say electronics, then the electronic stuff is going to end up with almost the whole 220 volts across it while ever the neutral is open circuit. As I said, may not be possible with your arrangement but here I have seen it happen where the customer had his own 3-phase transformer and the neutral connection at the pole was bad AND the house earth stake (here there is a neutral-earth bond in the house switchboard) was also bad and because the load in the house was far from balanced, I was getting one low phase-N voltage way below 200V and two very high ones well above 300V and that did damage appliances on the high phases. [Our supply system is 3 line plus neutral 415V phase to phase - for big motors and 240V phase to neutral for normal stuff or sometimes for rural properties 240V-0-240V giving a possible 480V to supply large motors Mess around and make a mistake and you're dead. Not like the tickly 120V stuff you have ;-))) | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1185 Registered: 10-2003 Posted From: 68.240.106.100 Rating: N/A |
Tony, thanks for the follow-up. I do not have neutral-ground bonding in the coach. The voltage from hot to neutral is the same as the hot to ground on both legs. The voltage between the hots between legs is ±239 volts. It does measure .28v between ground and neutral, but I'm assuming that's within specs. I *can* see how what you're describing could happen, but I doubt that's the case here. The one-leg-low-and-highly-unstable situation may be unrelated to all the 30 amp-only units in my immediate vicinity, it was just an assumption. Heck perhaps some work is being done and a highly undesirable drop/spike happened almost instantaneously. I saw the meter drop to 70, but it could have cut off altogether faster than I or the meter could see, and it could perhaps have jolted way past 120 in just those few seconds. Well L2 seems stable and just as soon as I can go do some checking I'll be doing some detective work. Oh, I just discovered that I also lost a printer. Rats. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 138 Registered: 10-2006 Posted From: 66.90.229.55 Rating: N/A |
Oh, and Fast Fred, they can't afford step-up transformers. ;) Some may suprise you by having purchased them at the electrical supply , rather than the RV shop. FF | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 2019 Registered: 1-2001 Posted From: 75.108.84.4 Rating: N/A |
The voltages Tony Lee is talking about is 50 hertz voltage. They do things quite a bit different than we do. For instance, most 50 hertz countries only use 240 volts. They do not use 120 volts. Richard |