| Author | Message | ||
| ken whitmore (Cowboykenny)
Registered Member Username: Cowboykenny Post Number: 26 Registered: 11-2007 Posted From: 98.16.160.174 Rating: |
New to the bus do and donts, Is an optional 220 hookup a bad idea? Is there any coaches out there with this? What is the usual campground hookup and is there any different ones other than 110? Also, what are the thoughts on these 110 instant heat showerheads? Thanks ken | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 125 Registered: 10-2003 Posted From: 66.165.176.60  Rating: N/A |
Mine came with a 50 Amp 220 service. To the best of my knowledge campgrounds are like marinas. If a pole has 50 amp it's 220. 30 amp is 110 although in reality 50 amp is just two legs of 30 110. I'm kind of locked unless I rework a few things. Right now the coach has a 220 JenAir range top and the basement furnace is 220 as well. Everything else is 110. | ||
| ken whitmore (Cowboykenny)
Registered Member Username: Cowboykenny Post Number: 28 Registered: 11-2007 Posted From: 98.16.160.174 Rating: N/A |
wow, You must have been sittin online. That was the fastest response in history. Have heard from several folks, 220 bad idea, but wondered why. I see no reason not to, but wanted to be safe, kenny | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 359 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Ken, Rv hookups come in essentially three ways, 20, 30, and 50 amps. The 20 and 30 amp services are 120 Volts, and the 50 Amp service is PROPERLY described as 120/240 Volt. The comment above about a 50 Amp service being two 30s is incorrect. Saying 110 or 220 is easier than saying 120 and 240, but this 'slang' leads to trouble when somebody tries to sell a 50 Hertz inverter, used overseas, on the auction site. They are actually 220 Volt, and can't be used in North America. 110 Volts hasn't been used in North America for about 70 years, Jerry can tell us exactly when the changeover was made. Now, a 30 amp 120 Volt service will give you 3600 Watts, period. A 50 amp service will give you 12,000 Watts, and the opportunity to use 240 Volt appliances. The only "down" side to a 50 amp hookup is that it takes a larger panel, and a generator that can be wired for 120/240. You could use a 50 amp cord and receptacle, and only connect one hot leg and the neutral (the ground goes without saying!) and have a 50 Amp 120 Volt service which would give you 6000 Watts... E me off bd if you have further questions, George | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 360 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
I forgot to comment on the showerhead, and apparently the editing process has had an eror in changeover, so here goes. Electric resistance heat gives out 3.41 BTU per Watt. 1 BTU raises the temperature of a pound of a substance a degree, and water weighs 8 1/2 pounds a gallon. So, ten gallons of water weighs 85 pounds, raising its temperature from 40 to 140 would require 8500 BTU. Conventional small electric storage water heaters usually have a 1500 Watt element, (I don't know what size element is in the "instant' you are describing) but a 1500 Watt element will draw 13 Amps of 120 Volt current. AND it will take it about hour and a half to heat it. So, can you put a 120 Volt 'instant' heater on a showerhead and get a warm shower? No. Sorry to rain on your campfire, but at least its better than a cold shower! Regards, George | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 126 Registered: 10-2003 Posted From: 66.165.176.60 Rating: N/A |
Thanks for the correction George. Perhaps I just described things wrong. On the boat I used to live on we had two 30 amp receptacles. If at a marina with 50 amp we had a pigtail adapter that would split that out into two legs one for each 30 amp. Our gentset was a 12KW wired for 240 with the load split evenly on each leg. I take it campgrounds either have 1 30 amp or 1 50 amp on a pole? (Message edited by timb on February 13, 2008) | ||
| Ed Jewett (Kristinsgrandpa)
Registered Member Username: Kristinsgrandpa Post Number: 367 Registered: 2-2003 Posted From: 64.24.211.237 Rating: N/A |
I was intrigued by the instant showerhead water heaters also but couldn't find anyplace close that sold repair parts. My water heater came from Lowes and you can get new elements in any hardware store, anywhere in the US. As for a 120V or 240V service, I've seen several people who have upgraded their 120V to 240 V because of necessity but I've never heard of anyone changing their 240V service to 120V. (I probably will now though) A dogbone adapter sill let you use a 240V service on a 120V, 30A receptacle. If you are going to have all propane appliances then a 120V, 30A will do fine. According to the National Electric code you are only allowed 5 circuits in an RV if you use a 30 Amp. service, unless you use a "listed Energy Management System". NEC Art. 551.42(D) 6 or more circuits you have to use a 50 Amp. service. Ed | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 361 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Tim, You're right in what you describe in your boat, and as you say it works. The problem arises when someone uses adapters and connects two 30 amp receptacles into a 50 amp cord, AND THE TWO 30 AMP RECEPTACLES ARE ON THE SAME HOT LEG! The neutral wire in a 120/240 circuit of any amperage only carries the un-balanced current between the legs. Lets just say you have a 50 amp service, and are drawing 30 amps on one leg, and 25 amps on the other, what is the neutral current? Answer #1 below, we just need to think a minute. IF the campground electrician wired two neighboring 30 amp receptacles on the SAME hot leg, and there is no code to prevent doing that, all the 120 volt appliances in the bus on both legs would work, but nothing 240 Volt would work. Now we are again drawing right at 30 amps on one leg, and 25 on the other again. What is the neutral current this time? Answer #1: 5 amps, (remember the neutral carries only the un-balanced current!) Answer #2: 55 AMPS! (its ALL un-balanced,) and now you are exceeding the rating of the neutral pin in the plug and receptacle, which will let the smoke out! The boat scenario will work well, and properly, and the neutral current will balance out at the adapter connection, (if anybody cares) and Edison will sleep well tonight. If we want to get REAL picky, the 30 amp receptacles are connected to a cord with a 50 amp breaker, but the boat should have 30 amp mains? (Ed, I appreciate your humor, we'll probably both hear now!) Regards, George | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 127 Registered: 10-2003 Posted From: 66.165.176.60 Rating: N/A |
George, You are correct there are two 30 amp mains and also a safty bar that prevents the genset and shore being on at the same time | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 195 Registered: 2-2006 Posted From: 70.223.142.72  Rating: N/A |
Hay George, This diagram may help your discription. Nick-  | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 196 Registered: 2-2006 Posted From: 70.223.142.72 Rating: N/A |
And this one too Nick-  | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 362 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Hey Nick, That's a good one, Thank You! George | ||
| Austin Scott Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 219 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
I have the 220 vac twist lock style with 3 poles on my bus and 50" cable. (2 hot and a ground/neutral) I also made up some adapters to adapt to several common connections. I even made up one to adapt to 2 seperate 120v lines. . | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 819 Registered: 11-2004 Posted From: 71.42.167.154 Rating: N/A |
Austin - If that is truly 220/240 you would need 4 wires with a dedicated earth ground - HTH | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 128 Registered: 10-2003 Posted From: 66.165.176.60 Rating: N/A |
If he has the twist style I'm thinking of there is a metal colar around the outside of the plug that provides the ground. This brings up a good question are all 50 amp 240 volt poles at a campground the style that Nick posted or do I need to plan on some adapters for different configurations | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 820 Registered: 11-2004 Posted From: 71.42.167.154 Rating: N/A |
Tim - my experience is they are the 50R's - twist locks are usually marine - HTH | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 728 Registered: 12-2000 Posted From: 76.3.169.171  Rating: N/A |
Every 50 amp receptacle that we have plugged into at campgrounds were identical to Nick's drawing. That said, they may be some that are different. Jack | ||
| ken whitmore (Cowboykenny)
Registered Member Username: Cowboykenny Post Number: 29 Registered: 11-2007 Posted From: 98.16.180.148 Rating: N/A |
Well, I seen those 110 instant showerheads on ebay starting at 49 bucks, I suppose they cant be to good after hearing the facts on heating water but was just wondering if anyone has tried one. Remember those tags on blowdryers when we were growing up? Just is crazy to see a cord that plugs in coming out of your showerhead !!! | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 363 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Here goes a little more clarification. All of the receptacles shown are NEMA (National Electrical Manufacturers Asociation) standard. Consequently, all campground connections will be the same, for the same amperage and voltage rating. For some reason, the 30 Amp 120 Volt RV plug and receptacle are a non-NEMA configuration, if you go into an electrical supply house and ask for a 30 amp 120 volt receptacle, what they will hand you won't fit your 30 amp cord. If Zimtok has what he says has, he's asking loudly for serious trouble! It sounds like what he is talking about is his method of attaching his shore cable to his bus, but it doesn't matter where in the circuit his error is, its dangerous! His post hasn't been up for long, and I'm the second person telling him he needs a seperate ground! Ground/neutral bonding has been discussed here at considerable depth, along with the serious consequences of failure to do it properly!!! NEMA went to a lot of work in designing all of the configurations so that people could not inadvertently over-voltage, or overload a circuit. Unfortunately, they are absolutely unable to defend against someone who deliberately buys a 3 prong receptacle and plug for a 4 prong application, and then puts two wires under one screw! I guess Catch 22 applies here, (if you don't know you did wrong, then you don't know not to post it?) THEY PUT A GREEN WIRE IN THAT CORD FOR A REASON!!!!! LOOK AT NICK'S POST, W (system ground) and G (equipment ground) are two seperate colors and wires for a good reason, and they are only grounded together at the power source, period. This is an insulting post to one person, for that I apologize, but if I keep one person from being electrocuted, its well worth it! George | ||
| Leland Bradley (Lee_bradley)
Registered Member Username: Lee_bradley Post Number: 23 Registered: 11-2006 Posted From: 138.163.0.42 Rating: N/A |
Then the manufacturers are adding to the confusion. The following is copied from a website selling inverters. The mobile inverters listed below have automatic ground switching, which allows the inverter to be grounded to the frame of the vehicle while traveling or to be grounded to the grid when plugged in. As I understand it, grounds must not be switched only the neutral is switched. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 364 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Lee, Actually, they're partly right, and you are too. The ground and neutral should be bonded ONLY at the power source, whether it be the inverter, generator, or the campground main meter panel. (Not the individual space pole or pedestal.) What the inverter manufacturer should have said was something like "the listed inverters provide neutral switching for proper grounding while operating. In the pass thru mode, they look to the outside source for proper neutral/ground connection." Then we could figure out that we would have to provide our own ground and neutral connection in the other places. The good transfer switches do this on their own, or it can be easily accomplished by using a 3 or 4 wire (depending on voltage) receptacle properly wired to the generator, and plugging the shore cord into it when generating. The problems occur when as in the above post, someone ties the ground and neutral together away from the power source, and the neutral wire is broken somewhere else in the campground, or the bus, or shore cord. Where is a 120 V load connected? Between the hot and the neutral, of course! Now the ground and neutral are connected at the improper connection, and there is no way for the neutral current that is being fed into the neutral wire by the load to go back to the neutral bar in the panel. So what happens? Since the whole bus is grounded, the whole aluminum and/or stainless skin now has 120 Volts to the dirt or wet grass you are standing on! Rubber tires insulate, so everything appears fine until you grab the door handle. If the problem arose because someone backed into a pedestal 4 spaces down, you are now trying to make the ground+neutral connection for half the campground, and shore cord just can't handle it, so the plug, or the improper splice will catch fire. Hope this helps, George | ||
| Leland Bradley (Lee_bradley)
Registered Member Username: Lee_bradley Post Number: 24 Registered: 11-2006 Posted From: 138.163.0.42 Rating: N/A |
Thanks George. Being the simple soul that I am, I think will use plug-ins to do my switching and leave the relays for the more technical people. | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 197 Registered: 2-2006 Posted From: 70.223.10.28 Rating: N/A |
OK, Here is another sinerio... 50 amp campground poles can also have 115v on each leg but not 240v between them. SO, you should always check with a meter... Nick-  | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 198 Registered: 2-2006 Posted From: 70.223.10.28 Rating: N/A |
The other photo will not post but, it shows 240v between the left and rigth terminals. Nick- | ||
| Moe Hollow (Moehollow)
Registered Member Username: Moehollow Post Number: 23 Registered: 12-2007 Posted From: 68.183.235.89 Rating: N/A |
A question and an answer. There are very low flow marine water heaters that run easily on 120v. I do not know the showerhead you are looking at, but it is quite possible there is one designed to give you hot water for a shower. The only thing is that it will not have much flow. We have a marine electric water heater for a vanity in a shop. It gets the job done, but it uses a special faucet attachment to diffuse the water enough for it to work. The question is about the electrical stuff. Is what you are saying that the ground and neutral should not be joined at the bus panel? Does this apply to 120 services as well as 240? Many appliances like water heaters and ovens seem to have three wire cords. Why is that okay in some circumstances? | ||
| Austin Scott Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 220 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
I understand the whole 3 pole/4 pole thing. Remember the old dryer connections? Same reason that they went to a 4 pole there. I also know how to use a test meter to make sure that the power is OK before plugging in. And I only plug into a few places that I'm sure the power is good. My house and my work place. The couple times I plugged into other locations I checked the power first and also ran a separate ground wire between the bus and the power source. (I made up adapters that can convert any standard extension cord into a ground cable. ) . | ||
| Austin Scott Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 221 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
Ken, On your instant shower head... I had the opportunity to use one when I was in Malaysia. the little motel I stayed at for a few days had one. The problem you have with these units is that the temperature of the water is controlled by how fast the water is going through the unit. The slower the water flow the hotter the water. So you can either have hot water or a lot of water but not both. The one I used in Malaysia was not very good because the water had to be at a near trickle before the water was hot enough. I tool cold showers most of the time I was there. . | ||
| ken whitmore (Cowboykenny)
Registered Member Username: Cowboykenny Post Number: 30 Registered: 11-2007 Posted From: 98.16.180.148 Rating: N/A |
Thanks for the info folks, It has helped me and I will use 220 only after checking before I plug in. Cowboy | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 821 Registered: 11-2004 Posted From: 71.42.167.154 Rating: N/A |
****The couple times I plugged into other locations I checked the power first and also ran a separate ground wire between the bus and the power source**** Austin - I would caution you to consult an electrician - Electricity follows the path of least resistance, and if I'm understanding this correctly you may have a hazardous situation, i.e. you maybe come the earth ground - FWIW Ken - I haven't done anything like his (but I have used the 240 volt Seisco units) but you may want to call the manuf. and ask if any one has ever hooked 2 up in series, say 2 1500 watt units drawing 25 amps on a 30a 120v circuit - FWIW | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 706 Registered: 1-2003 Posted From: 72.171.0.140  Rating: N/A |
A few misconceptions that have been bandied about in this discussion need to be corrected. First off, the ground for any RV power supply MUST run together with the current-carrying conductors. That means in the same cable. It is contrary to code, law, and safe practice to do otherwise. (George has already said this, but it bears reiterating.) Secondly, the ground and neutral (called, confusingly, the grounding and grounded conductors in the code) must be separate conductors on an RV power supply. As has already been noted, the locking-type 50-amp connector that many manufacturers use for detachable 50-amp shore cables actually has four separate conductors -- three blades, and a metal grounding collar. This connector does not conform to a NEMA standard, and was originated by Marinco, makers of marine shore power components. Twist-LockŪ, by the way, is a registered trademark of the Hubbell corporation, not a generic term for locking connectors, which is what they are more properly called. Hubbell, by the way, does make a connector to the Marinco standard, under license. With all due deference to my friend George, the notion that 30-amp RV connectors are not NEMA compliant is incorrect. Most common NEMA charts won't list them, because they are not legal or appropriate anywhere except in RV installations, but it is NEMA standard "TT-30P" (plug) and "TT-30R" (receptacle), which is for "Travel Trailer" use. This is the receptacle specified in the NEC for use with 30amp RV service. Back when the travel trailer standards were being set, the thinking was that a unique plug and receptacle configuration was necessary to preclude trailers and 30-amp appliances from being interchanged. The 30 amp appliance standard is 5-30P and 5-30R (and the locking type, L5-30P and L5-30R). (I carry a 5-30P to TT5-30R adapter explicitly for the purpose of connecting to 30-amp shop outlets.) When the 50-amp standards came along, there was no longer a concern about interchangeability, and so the already existing NEMA 14-50P/14-50R standard was adopted. Many household ranges use this same plug. Note, again, that the NEC specifies this plug and receptacle configuration for 50 amp, 240-volt RV shore power installations. Lastly, I know of no inverter that implements "ground switching." I believe the wording quoted above represents some seller's misunderstanding of how inverter manufacturers implement automatic ground-to-neutral bonding, a common feature of modern inverters designed for RV use. Incidentally, to elaborate on Nick's statement about finding 50-amp receptacles with 120 hot-to-neutral but not 240 hot-to-hot, bear in mind that many campgrounds, especially ones attached to large commercial facilities such as fairgrounds, run their campground power from 3-phase panels. These will read 120 volts hot-to-neutral and 208 volts hot-to-hot. Unless you have actual 240-volt appliances, there is nothing wrong with this type of power and it is safe to use. Even many 240-volt items such as radiant stoves are also rated to work on 208. FWIW. -Sean http://OurOdyssey.BlogSpot.com | ||
| Denis (Denis)
Registered Member Username: Denis Post Number: 15 Registered: 11-2005 Posted From: 75.187.210.173 Rating: N/A |
"As has already been noted, the locking-type 50-amp connector that many manufacturers use for detachable 50-amp shore cables actually has four separate conductors -- three blades, and a metal grounding collar. This connector does not conform to a NEMA standard, and was originated by Marinco, makers of marine shore power components. Twist-LockŪ, by the way, is a registered trademark of the Hubbell corporation, not a generic term for locking connectors, which is what they are more properly called. Hubbell, by the way, does make a connector to the Marinco standard, under license." Sean, we have the Marinco connection to the coach, are you saying this is Not a good connection for this purpose? Or is it just not to NEMA standards? Thanks for your expertise, Denis | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 707 Registered: 1-2003 Posted From: 72.171.0.144 Rating: N/A |
Denis, Sorry, did not mean to imply there is anything wrong with the Marinco connector. We use this type ourselves. It is well built and UL listed. NEMA is merely a trade organization of electrical manufacturers, analogous to, for example, the RVIA being a trade organization for RV manufacturers. The purpose behind the standards that NEMA sets is to ensure that the components built by many different manufacturers are interchangeable. A standard household socket (NEMA 5-15R) made by Leviton will have the same dimensions and mechanical properties as one made by Eagle. Without these kinds of standards, you could not be assured that if your lamp plugs in just fine to a Leviton that it will also plug in fine to an Eagle. The Marinco 50-amp marine shore power connector does have a set of specifications, and many manufacturers make hardware to this spec which does interchange -- I have seen at least three different brands including Marinco itself. But NEMA has not adopted it as an industry-wide standard. Hope this clears things up. -Sean http://OurOdyssey.BlogSpot.com | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 822 Registered: 11-2004 Posted From: 71.180.67.169 Rating: N/A |
*****Incidentally, to elaborate on Nick's statement about finding 50-amp receptacles with 120 hot-to-neutral but not 240 hot-to-hot, bear in mind that many campgrounds, especially ones attached to large commercial facilities such as fairgrounds, run their campground power from 3-phase panels. These will read 120 volts hot-to-neutral and 208 volts hot-to-hot. Unless you have actual 240-volt appliances, there is nothing wrong with this type of power and it is safe to use. Even many 240-volt items such as radiant stoves are also rated to work on 208.***** A wye 3 phase power system will always provide 480v between any 2 hot legs and 120/208v between any leg and the neutral (720v tied) - while a delta 3 phase power system provides 480v between any 2 hot legs and 120/240v between any leg and neutral (720v tied) - Am I missing anything? (Message edited by niles500 on February 16, 2008) | ||
| Denis (Denis)
Registered Member Username: Denis Post Number: 16 Registered: 11-2005 Posted From: 75.187.210.173 Rating: N/A |
Thanks Sean, I liked the connector and now I can still be comfortable with it ! Denis | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 2033 Registered: 1-2001 Posted From: 75.108.85.14 Rating: N/A |
quote "A wye 3 phase power system will always provide 480v between any 2 hot legs and 120/208v between any leg and the neutral (720v tied) - while a delta 3 phase power system provides 480v between any 2 hot legs and 120/240v between any leg and neutral (720v tied) - Am I missing anything?" Niles I do not think this is completely accurate. I posted a writeup on the other board here: http://www.busconversions.com/bbs/index.php?topic=7364.0 Richard | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 708 Registered: 1-2003 Posted From: 67.142.130.14 Rating: N/A |
Richard did a great job explaining 3-phase power in that other thread. And, yes, I was referring to 208/120 Wye configuration, which is very common in commercial settings, and which we've encountered in campground pedestals several times. -Sean http://OurOdyssey.BlogSpot.com | ||
| Ian Giffin (Admin)
Board Administrator Username: Admin Post Number: 1068 Registered: 7-1997 Posted From: 24.239.7.250  Rating: N/A |
And to try to eliminate the necessity to jump from one board to another to follow this thread, that explanation is: "Please note that this post has been revised to remove erroneous information regarding three phase Delta connections. DML There have been several postings regarding AC voltage distribution recently, and which contain some misleading information. Hopefully I can shed some light on this for anyone that might be interested. GENERAL The most standard three phase higher voltage distribution system, within a facility, is 480/277 volts in a Wye configuration. Voltage between any two of the three hot legs is 480 volts. Voltage between any one of the hot legs and neutral is 277 volts. The neutral connection is common to all three of the hot legs. All neutral current flows thru this common neutral. This prevents installing separate neutrals for each 277 volt connection. For example, many industrial fluorescent lights are designed to operate from the 277 voltage taken from one hot leg and the common neutral leg. These are typically utilized in an industrial environment. For lower voltage requirements this voltage (480/277) is stepped down, by transformer to two different configurations: 1. 240/120 volts three phase delta configuration for industrial applications such as manufacturing facilities or, 2. 208/120 volts three phase Wye configuration for commercial applications such as office buildings. 120 volt single phase voltages are derived from one of these two configurations using two hot legs and a neutral. DELTA CONFIGURATION VOLTAGES In the 240/120 single phase connection, for the campground, two of the hot legs from the utility supply, such as phase A and phase B, are connected and the neutral is derived from the center connection between phases A and B. 240 volts is of course from the Phase A and phase B legs and 120 volts from either the phase A or phase B hot leg and the center tap neutral. WYE CONFIGURATION VOLTAGES The 208/120 Wye configuration is a whole totally different animal. The neutral is a single conductor taken from the center point of the Wye where the three windings are tied together at the junction of the Wye. This configuration is especially useful in a building where a lot of 120 volt outlets are required, such as a computer facility. Single phase 208 volts is available from A and B, A and C or C and B. 120 volts is available from the common neutral and either A or B or C. Having said that, I am not aware of any campgrounds that are configured like this, but it certainly is possible. Comments, suggestions or corrections to this is welcomed since I might have got a bad batch of brew last night. LOL Richard BTW, it is common for the Wye conductor neutral to be double the size of any of the hot conductors since the possibility exists that the neutral current may be higher than any one of the hot conductors. This is particularly true where a lot of PC type computers are installed." Thank you DML! Ian www.busnut.com | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 228 Registered: 7-2006 Posted From: 4.240.213.167 Rating: N/A |
Yup....DML...thanx. Very informative! FWIW RCB | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 2034 Registered: 1-2001 Posted From: 75.108.85.14 Rating: N/A |
Thank you I@n for posting this here. I was actually trying to direct some of our members to your board in case they were not aware of it. Of course, it also directed some of your members to the other board also. I also wanted to be sure it was in the MAK archives also. Along the same lines, I recently asked Russ if he could provide me a copy of the post(s) he supplied to you so I could add it to the MAK help board since I did not really know how you would feel about me copying something from the BNO board to the NAK board. Never really got it resolved, so I dropped it. It appears as if you have no problem with this. Richard | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1169 Registered: 5-2001 Posted From: 65.74.66.116 Rating: N/A |
Richard, are you sure about the three neutrals in the delta connection? I would have thought that would have been a big no-no. We are delta connected here in Ketchikan, but the utility guys here have told me that the only neutral is between the A and B legs. I was told that the C leg is referred to as the wild leg. The way they work that is to bank additional transformers onto the A-B pair when more 120/240 single phase is needed. The wild leg is only used with three phase 240. This setup does not do much for self balancing, but we don't hear them making any plans to change the system over to something else. Our system went in before WWII, I am told. Recently, the harbor upgrades included a switch to 120/208, which I think was a good idea. By the way, they used the Marinco connector with the band on the side of the plug for the safety ground, I think. Thanks for the post. Tom Caffrey PD-4106-2576 Suncatcher Ketchikan, Alaska | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 2035 Registered: 1-2001 Posted From: 75.108.85.14 Rating: N/A |
No I am not sure of this. This was what I was told by somebody previously. I might have got mixed up. Not hard for an old fart. Here is the response I posted on the other board: It is possible that they use three different single phase step down transformers for power distribution in a campground environment. The input from the utility for the first transformer connected to phase A and B with its center tap neutral. The input from the utility for the second transformer connected to phase B and C with its center tap neutral. The input for the third transformer connected to phase A and C with its center tap the neutral for that transformer. Under this configuration, then it is possible the three neutrals could be connected together and to ground. I am not entirely sure on this connection. Maybe Sean has the answer. Richard (Message edited by DrivingMissLazy on February 16, 2008) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 365 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Ian's post says almost all of it, and very well. A 120/240 Delta circuit will have two legs of 120 Volts line to neutral, and one leg with 208 volts. The delta setup uses two transformers, the two 120 V line to neutral legs come from one transformer, which is center tapped just like a single phase system. The second transformer's secondary winding only uses two wires off the ends, one connected to one side of the secondary of the other xformer, and one supplying the 3rd leg for the 3 phase, and by accident 208 to neutral. A couple of more things to think about here, the wye connected 120/208 service will be 120 degrees apart between the phases, not 180, as in a single phase 120/240 circuit. There will always be neutral current, even with three exactly balanced legs. Tom has the delta connection exactly correct, immediately above. The 'wild' leg will be 208 volts. The comments further above about 480V phase to phase and 120/ 208 line to neutral just aren't correct. The three standard US voltages are 120/208, which is Wye connected, 120/240 which is Delta connected, and 277/480, which is also USUALLY Wye connected. Richard's question above should be explained as the 3 primary windings connected Delta and one leg of each secondary connected together, no center taps, and voila, when you look at the voltage from any outside point on the wye, (or a star if you are a furriner) to the midpoint, you get line to neutral, and if you go between any two outside points you get phase to phase. Way above, I said "NON NEMA CONFIGURED," not NON NEMA COMPLIANT, sorry to be picky, but! One last thing, Nick's scenario above where both hot legs are on the same phase is exactly what I described in my 30 + 25 question above. What happens when you now add 30 or 40 and 30 or 40? The answer is a HECK OF A LOT MORE than the 50 amps the neutral is rated for! Along comes the 4104 owner with his neutral and ground connected together with a 3 pole connector instead of a 4, and guess what? I think 3 of us so far have suggested he go make it right before it is too late. G | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 200 Registered: 2-2006 Posted From: 70.223.15.79 Rating: N/A |
One last thing, Nick's scenario above where both hot legs are on the same phase is exactly what I described in my 30 + 25 question above. What happens when you now add 30 or 40 and 30 or 40? The answer is a HECK OF A LOT MORE than the 50 amps the neutral is rated for! Along comes the 4104 owner with his neutral and ground connected together with a 3 pole connector instead of a 4, and guess what? I think 3 of us so far have suggested he go make it right before it is too late. G Yes George, I want to see how many guy's are aware of this.... I have see this at rally fields. Nick- | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 2036 Registered: 1-2001 Posted From: 75.108.85.14 Rating: |
I am now convinced that I made an error when I stated there could be three different neutrals from the three phase delta transformer. I now suspect that a campground only distributes only one single phase from a delta transformer. I suspect that some of Dr. Dave's defective brew made its way up to the hills of WV. LOL I a going to go back and correct my post on the MAK board and am asking I@N how to get the correction onto this board. BTW, I@N's post was actually a copy of my post from the MAK board, so the error in his post is actually my own error. Sorry guys for the screwup. I think this goes to show that even with over 50 years of dealing with electrical power, mistakes can be made and everyone should be very careful in any wiring that they are doing to the coach. Mistakes can be fatal. Richard (Message edited by DrivingMissLazy on February 17, 2008) (Richard: I have corrected your above post by copy/paste again from the MAK board. |@n.) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 366 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Richard gets my vote for fessing up to an oops! A whole lot of people simply wouldn't reply. Who does a store owner call when his refrigeration fails? Usually not an electrician, its a refrigeration contractor. At least 50% of the time the trouble is electrical, consequently many refrigeration/AC contractors are better electrical troubleshooters than many electricians. For what thats worth... If a campground is fed from delta connected transformers (2 on the pole, one larger than the other) the secondary HAS to come from the TWO hot legs of the center tapped transformer to give you 120/240. The 3rd leg is the "wild or stinger" leg which is 208 Volts to neutral. This configuration is used in residential/small commercial areas, because it allows utility companies to provide 120/240 single phase, and 240 3 phase to both residential customers and small commercial applications with one set of two transformers, and one set of four secondary wires. Open delta 3 phase power quality isn't quite as good as wye connected 3 phase, so it usually isn't used for high horsepower applications. The post way above about 120/208 line to neutral voltage in a 480 volt system is in error. A 208 volt system is always 120 v to neutral, a 480 v system is always 277 v to neutral. The 4104 owner with the 3 pole connector now has me, Niles and Sean after him to straighten it out, and it doesn't matter how many seperate grounds he runs to wherever, he still has the ground and neutral connected at both his twistlock receptacle, and his cord cap! This is an NEC violation, and they are concerned enough about second grounds, to require the inspection of 120/240 V appliances installed in RVs to make sure the ground and neutral aren't inadvertently connected inside them! Well, you can lead a horse to water, you just can't make it drink. Also, you can usually tell teenagers, you just can't tell them much. I'm done. G | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 218 Registered: 10-2006 Posted From: 66.90.229.254 Rating: N/A |
We use a very simple setup on the Sportscar. We have both 50A 240v cable and a seperate 30A 120V cable The heavy 240v cable has a socket end and plugs into a 240v plug on the coach inlet breaker box. There is no 240 users aboard runs 2 circuits , one for each compressor of the basement air cond, and all other house loads.. Each leg has its own breaker/switch panel. When only (mostly) 120V is at the camp site the 120V power cord is used. To make it work an adapter is REQUIRED that simply joins the red and black wires inside the adapter. One end is the 240V socket to plug the coach into, the other a std RV plug for the 120v 30A power cord. This works fine , most of the time all that is needed is the light weight 30a RV cord , the few times a year we can use both air cond , in the right RV park. The only hassle is load control dicepline is required when in a 15A city park, friends house , or Canadian "Full Service" campground. THE 15-30 Adapter plug to convert the 30a cable to 15A wont take it if the HW heater is on , and you try for a second resistance load. Thats what the 2 AC control panels are for!! For inverter use the inverter outlet is also a 240V socket (wired for 120) that the coach plugs into instead . Inside the coach , next to the breaker boxes are 2 more sockets. One is wired to the noisemaker output , the other to the lead in wiring. So to switch from land current to noisemaker is a simple indoors switching of a plug . No Automatic transfer switch to repurchase after every thunder storm. Works for me, FF |
