central vac on AFCI

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galen8146

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I was just told today, by a fellow electrician, that it is a violation to put a central vacuum outlet,(not the main power unit) on a AFCI outlet (receptacle). This is the kind with the Direct Connect Current-Carrying Crushproof Hose. Is there a problem with this? My logic is that you can plug in a normal vacuum, why can't you direct wire a central vacuum outlet that only runs the power brush?
Thanks
:confused:
 
Re: central vac on AFCI

That's what I think, I am not sure what his problem is other then he wants me to get a permit to install the vacuum outlet wires in to the receptacle boxes and get the job inspected again, but this is HIS job, not mine and if there is a money question he should charge a fee for a change from the original bid. I can't find a code ref. that says no direct wire outlets in a AFCI circuit. He is going to call me back tonight and I will let you know later what his beef is.
Thanks for the quick reply
Galen
;)
 
Re: central vac on AFCI

And to add to Tom and Ryan's replys, tell this fellow that in the near future AFCI's will be required in many more areas than are required now.

Whether we like it or not, AFCI's will follow a path similar to the GFCI.

Roger
 
Re: central vac on AFCI

After reading the posts concerning the heat being generated by AFCI breakers, it sure sounds like this heat problem may need to be looked at a bit closer. Computers and many other types of electronic equipment all have cooling fans installed on them because the electronic components generate heat. Heat causes electronic components to fail. The Central Proscessing Unit,(CPU), of todays personal computers generate so much heat when operating, the manufacturers have had to go as far as installing a fan directly on the component to keep it cool. And these machines under most circumstances operate less than 12 hours a day. These new circuit breakers having electronic components inside of them, plus continuous operation in a totally enclosed steel box, are going to need some means to keep cool or failures seem evident. Having ventilation holes on the panels would eliminate quite a bit of the heat, but wouldn't that be a code violation?
 
Re: central vac on AFCI

There seems to be a lot of confusion around the heat generated by AFCIs. There are electronics in the breaker that generate heat BUT this is not anything outside the operating range of the breakers. They can feel hot to the touch while still falling within the UL standards which are no more than a 50 deg C rise above ambient. The heat rise seen in AFCIs is comparable to GFCIs, which have been used for the past 25+ years. The face of the breakers can actually be warmer than the terminals due to the location of the electronics. This temperature rise, even in a panel full of AFCIs would not affect the safety or performance of the breakers.
 
Re: central vac on AFCI

I did a word search of NEC 2003. I found the acronym ?AFCI? twice, and the combination of ?arc? and ?fault? seven times. In every instance, the NEC requirement states instances in which an AFCI must be installed. The NEC contains no prohibition against installing an AFCI anywhere or under any circumstances. Your fellow electrician is most definitely wrong.

That said, there are circumstances in which an AFCI would not be desirable. Some types of equipment would be repeatedly tripped, even it they were operating properly. You would not ?want? to install an AFCI for those loads. But such discussions are design issues, and are not addressed in the NEC.
 
Re: central vac on AFCI

IMHO the spread of AFCIs will not go beyond the bedroom (sleeping rooms) until the combination type AFCIs have proven themselves. At that time, I expect the combination type AFCI to be required on all 15 and 20 ampere, 125 volt circuits in residential use. :D
 
Re: central vac on AFCI

No NEC prohibition. Look to your state and local codes to see what they say. Many states, counties, parishes, and cities have their own local code that modifies (adds or subtracts) the NEC.

Side issue: As for AFCI cooling there would be no need for active (fan) cooling. If needed, it could be done with heat sinks, or if further cooling is needed it can be done with "heat pipe" cooling technology. Passive heat pipe cooling technology can exceed that provided by fans/heatsinks. There is active heat pipe cooling too (uses heat pipes and fans).

Here's a quote from benchtest.com:
Heat Pipes
As the story goes, it was in 1963 when a Los Alamos National Research Laboratory engineer named George Grover demonstrated the first heat pipe. Heat pipe technology was borrowed from simple heat conducting pipes used by English bakers 100 years ago. Since 1963, heat pipes progressed and modern applications of this technology range from miniature heat pipes for cooling processors inside laptop computers, to groups of half inch diameter and five feet long pipes that will be used in NASA spacecraft, to pipes of two inch diameters (or more) which are used to cool injection molds used in plastic forming. The lengths of the pipes can vary from inches to 24 feet or more.

A lithium filled heat pipe developed at Los Alamos in the mid 1980s transferred heat energy at a power density of 23 kilowatts per square centimeter. If you consider that the heat emitted from the sun's surface is roughly six kilowatts per square centimeter, you begin to realize the enormous heat transferring capacity of the heat pipe.

How It Works:
Heat pipes are generally composed of a tube, closed on each end, with fluid in it. One end takes in heat and the other expels it. The heat entering the "hot" end of the tube boils the liquid which turns it into a vapor. The vapor expands in volume and travels to the "cold" end where it condenses to a liquid and gives up its heat. The fluid is then returned to the hot end by gravity or a wick and starts the process again. The working fluid can be water in a negative pressure atmosphere or a fluid, such as freon, which is pressurized to maintain its fluid state.

Ideally there would be no temperature difference between the hot and cold ends regardless of what the rate of heat transfer is. However, there are physical limits to the rate of heat flow that can be transferred for a given temperature difference between the hot and cold ends. The heat must conduct through several interfaces and conditions. This includes heat transferred through varying thickness of the pipe walls, the thermal path of the liquid before it boils and after it condenses, and pressure differences between the hot and cold ends caused by aerodynamic friction. A professionally manufactured heat pipe can have a delta T as low as 2?F (1?C). However, with my rather crude building methods, I would consider a delta T of 10?F (5.6?C) a success.
Click to expand...
Now, back to the gist of this thread.
[Edit add: Link to more details on heat pipe technology ]

[ May 09, 2004, 01:31 PM: Message edited by: awwt ]
 
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