wittmeba
Roanoke, Va
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wa8yxm,
Quote:or 2: (http://www.psrv.net) takes one big ticket item and "isolates" it from your RV completly NOTE that this device actually WORKS
What does it do? I still sense that it is conditional to particular pedestal wiring. Can you add?
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jhilley
Buxton, ND
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wittmeba wrote:wa8yxm,
Quote:or 2: (http://www.psrv.net) takes one big ticket item and "isolates" it from your RV completly NOTE that this device actually WORKS
What does it do? I still sense that it is conditional to particular pedestal wiring. Can you add?
No, you just need two separate receptacles. It is isolated in the RV. Most gensets have two 120 VAC outputs, one is dedicated to the rear air conditioner in 30 amp RVs. The device from psrv just makes use of the existing wiring and provides a fool proof method of using either the genset or two receptacles on the power pedestal. It allows you to use the 20 amp 120 VAC receptacle available on almost all power pedestals.
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RLS7201
Gladstone, MO
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Rick Jay wrote:ejforwood wrote:The amperage capacity of a wire does not double by using two wires. Check the Code! A 30 amp circuit requires that you use ONE set of wires of sufficent size to carry the entire load from the source (breaker panel) to the load (outlet).
I agree, the NEC does not allow you to parallel wires (in most cases) to increase ampacity. But "splitting hairs" here and looking at the theoretical limits, according to this chart, the maximum amps for an enclosed copper conductor of 14 gauge (typical 15A wiring) is listed at 17 Amps. The maximum amps for an enclosed copper conductor of 10 gauge (typical for 30A wiring) is listed at 33 amps. So, technically, two paralleld 14 gauge wires would equal the ampacity of a single 10 gauge wire.
Should this be done? Of coure not, for all of the reasons mentioned in this thread. It's just one of those things that might look good on paper, but is apt to be very problematic (and unsafe) in practice.
~Rick
Not to dispute NEC but look at service entrances at any industrial complex. You'll find 2 or more paralleled leads to increase ampacity.
Look at cross country power lines, again you'll find as many as 4 paralleled lines to increase ampacity. The argument about current seeking the path of least resistance is valid in most cases but paralleled lines do work. In fact Fleetwood run 2 10 gauge wires from my inverter to the batteries, with a 30 amp circuit breaker on each wire. Go figure.
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Wayne Dohnal
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Quote:
Not to dispute NEC but look at service entrances at any industrial complex. You'll find 2 or more paralleled leads to increase ampacity.
Look at cross country power lines, again you'll find as many as 4 paralleled lines to increase ampacity. The argument about current seeking the path of least resistance is valid in most cases but paralleled lines do work. In fact Fleetwood run 2 10 gauge wires from my inverter to the batteries, with a 30 amp circuit breaker on each wire. Go figure. NEC 310.4(A)requires paralleled conductors to have a minimum size of 1/0 AWG. There are a few additional requirements. The Fleetwood parallel wires you described would appear to violate this. There's always a chance that some other part of the code would override Chapter 3 for a low voltage and/or RV application. At the industrial complex, those extra wires may or may not be for separate services, which wouldn't be considered parallel conductors.
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randrx2
Newport News, VA
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Most people are saying that there could be extra current on one of the 15A circuits. So what? Wouldn't the 15A breaker trip on this overcurrent?
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wittmeba
Roanoke, Va
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jhilley or wa8yxm,
Im still trying to understand what this does.
What I read here http://www.psrv.net/Psbroc59.pdf this will provide a convenient and safe way for you to connect to a second 20 amp shore line OR a generator to serve as a second service.
- Assumes you have a 30 amp rig and a genset wired to a second service within your RV.
- Assumes your front A/C is wired to the main 30 amp service.
- Assumes your rear (second) A/C is separated and available thru the genset receptacle.
- Assumes the pedestal is wired with isolated circuits to avoid overload when using both. << My thoughts here are if the RV park feels you should use either 20 amp or 30 amp but not both, there may not be adaquet power to power both.
Is that correct?
This is what I am saying about the pedestal wiring.
* This post was
edited 08/20/08 06:31am by wittmeba *
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jhilley
Buxton, ND
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wittmeba
Your assumptions are mostly correct. It is up to the park and the installing electrician to correctly install the power pedestals. Each 20 amp, 30 amp and 50 amp receptacle on the pedestal has it's own circuit breaker. Each pedestal has a circuit breaker in the distribution panel, which should be sized for the load and wiring to the pedestal. If every pedestal is loaded to the max there would probably be problems. In most cases this wouldn't happen, but could happen on a hot day with everyone running air conditioners. This leads to low voltage and brown outs. Most pedestals now have a 20 amp, 30 amp and 50 amp receptacle so are plenty large to handle the use of this adapter.
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vermilye
Oswego, NY, USA
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Quote:Most people are saying that there could be extra current on one of the 15A circuits. So what? Wouldn't the 15A breaker trip on this overcurrent? Since the extra current will be on the neutral, which is unfused, there is no breaker to trip.
If you parallel opposite legs, you will have a direct short. You won't put 240V into your RV because one or both 15 amp breakers will open (probably with a shower of sparks.) If you parallel 2 circuits on the same leg it will appear to work, but you may cause a failure of one of the neutrals for the reasons described previously, you will be in violation of the NEC, and have a situation where shutting off one breaker would still leave the connection hot. If you use 15 amp plugs & a 30 amp receptacle to do the paralleling, the 2nd male plug will be hot once the first is connected - a very bad idea...
As to paralleled large conductors, wire sizes only go so large because they need to be pulled through conduit (around bends, etc.) When current demands are higher than the largest single wire size available, it meets code to parallel smaller conductors, however as Wayne stated, they have minimum wire size restrictions as well as requirements that they be the same length, insulation, etc.
One last point on "cross country power lines" - the multiple conductors are actually used to produce a "virtual" larger conductor, not for current carrying purposes, but to reduce corona discharge at the high voltages used.
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SWMO
Southwest Missouri
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Quote:..how is achieving what I'm curious about different than linking two gennies?
You control the genny's from generation to consumption. In the situation you propose, if I understand it, you have little control. The supplier of the electricity has made decisions you can't change, and don't allow you much in the way of options.
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Golden_HVAC
Fulltime, CA, USA
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MCrankyPants wrote:OK...should have clarified...
NO WAY would I try this myself, I'd pay to have it done, here's my situation:
We do Renaissance Fairs for a living, and we camp behind our booth at the AZ show.
We have a 15 amp breaker and outlet box to the booth, and another 15 amp breaker and outlet for the coach.
During the week we don't use the booth power, and I know you can parallel two Honda gennies into one plug, so I was just curious if this sort of thing could be done in my situation?
again...I would not do this myself, just don't want to pay the fair electrician for a service call if it isn't possible.
Thanks!
Hi,
You can do exactly what I descibed.
Plug in the refrigerator and battery charger to one extension cord from the booth 15 amp breaker, and then plug in the whole RV to another 15 amp receptacle. (with is was 20 amps to allow running the rooftop A/C - my A/C uses 12.5 amps on high fan speed, 11.5 on low fan speed, that would be very close to tripping a 15 amp breaker).
By the way, when plugging into a laundry circuit breaker, many times they are wired with seperate circuit breakers, so it might be possible to have 120/240 volts there. Also when at the fair, you might have the same phase to both receptacles, or you might have differant phases, so trying to combind 2 extension cords with differant phases will cause sparking! And even if on the same phase, but one extension cord is 100' longer than the other, that can cause problems too.
By using two extension cords, you can do it safely! Putting less than 15 amps of load on each power cord, and you will not trip the circuit breaker either.
If you only had a Trace SW 2512 inverter. It can assist the input power source to run loads larger than the input capacity. If set for 15 amp shore power, and the load goes over 14 amps, the inverter will sinc with the input power and produce power from the batteries, up to the full capacity of the inverter and batteries. So by using that inverter, a 600 watt solar system, and plugging in a 45 amp battery charger to the other 15 amp circuit, you could in theroy run both air conditioners from a large battery bank and one 15 amp breaker that has less than 14 amps going through it, with the inverter making up the balance of the power required, and the 45 amp charger keeping the batteries above 11.5 volts.
You might be able to find a SW 2512 inverter used (trace does not sell them new anymore). Check out this place, they used to sell them and get in inverters when owners want to upgrade to a larger model.
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