Good Morning, while I saw this at a woodworking site, I thought I would post it for comments..

..the guy who wrote this claims he is an EI in 5 Western States.......

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...."Maybe it would help if I explained the situation in which multiple receptacles are typically installed on a 50A circuit, and why.

I'll use my own shop as an example.  I have typical midrange/light industrial tools.  For example, I have a Makita 2030 jointer/planer.  It has a 2 HP motor and draws 18A when running.  Typical startup current is double that, 36 A (double is a rule of thumb for motor startup).

Suppose I use a 20A circuit, with 10 guage wire, which appears to meet NEC for a motor circuit.  I also use arc fault circuit interruptors and a GFCI.  What happens when I turn on the motor?  The breaker trips - the AFCI breakers respond quickly to overcurrent, unlike traditional breakers that respond slowly (if at all) to faults.  If I use a traditional breaker, the motor will start, but the lights will dim and the motor voltage will drop, stressing the motor.  That, and traditional breakers will only trip due to a sustained, significant overcurrent condition - so they often don't trip if a motor winding shorts, for example. (which is why AFCI's should be used for all circuits, even though that is not yet a code requirement - currently AFCIs are only required for bedrooms)

There are a couple of solutions to this problem.  I could wire a dedicated 40A circuit with 6 guage wire to each machine.  That would work, but is overly expensive.  In addition, even with derating there are practical limits to how many such circuits I can legally put in my breaker panel.  It's likely 200A service would not be sufficient if I am running my house off the same panel.

The better (IMHO) solution is to use a single 40A or 50A circuit with multiple 20A receptacles.  I typically would wire this with 6 guage wire ( 4 is even better), which resolves the light dimming/motor drop issue.  As noted previously, this meets NEC requirements.  One significant benefit is that only one 40A or 50A circuit is added to the breaker panel, so I can still power my house with 200A sercvice.  The only real disadvantage is that you can't start multiple machines simultaneously, but for most of us with small shops that's not a big deal. "

Well I'm no NEC expert, but since when has it been permissible to put 20A recepts on a 50A branch circuit?

I didn't know that was possible either, like you I ain't an expert...

...but this guy is looney ....this is his response to some fella merely wondering what size breaker to install for a 12A saw.
......the WW conversation has entered the Twilight Zone since this EI?insists his way is OK

I think they are confusing what is acceptible in article 430 for motor circuits and what you can do with receptacles.
That is still way to big for the motors he is talking about.

Seems that what he should have done is install a subpanel in his shop on that 50A circuit, then feed his equipment with appropriate sized branch circuits.

I don't know what thumb he is looking on that has a rule stating start-up is twice the full load current. Unless it is on an autotransformer or some reduced current starter the motor startup current is at least 6 X Full Load Current.

Should ask him why they don't only sell AFCI circuit breakers if the regular kind don't work. LOL

I think that this guy has been sitting too long in his shop smoking crack. LOL


[This message has been edited by RobbieD (edited 02-02-2006).]

Anyone remember that skit the Eddie Murphy used to do on SNL? He uses a lot of big words poorly put together. If you didn't know what the words meant, it might sound like it made sense, but knowing what they meant made it giberish.... Then they fade back, and he is in a prison cell. I think that is what you are dealing with.

Some subjects get me a little wound up, so I'll try to remain calm and be nice.:-)

First, remember that anyone can claim to be anything on the internet. Second, even if the qualifications or titles are correct, every profession has its' doofusses.

Finally, I am a little tired of folks whose world model has the electrician at the bottom of a "rank ladder," with inspectors, engineers, production managers, and someones' Uncle Fred "higher up."
This is simply not true. While these other professions have their own place in the grand scheme of things, it is the electrician who is THE expert on things electrical. Period. Apprentice, Journeyman, Master...this is your area of expertise. Everyone else is in the supporting cast.

Finally, there is a reason it's called a SKILLED trade. Without learning the trade practices, and having the expiernce of seeing a variety of methods over time....there are large parts of the NEC that simply don't make much sense. I wish I had a dollar for every "code expert" I've met who casually disregards the part of the NEC wher it says "not to be used as a design manual!"

Back on topic....our "EI" has a flawed understanding of the code, motor controls, and even basic theory. Off the cuff, I'd venture that he has some power quality problems that are the direct result of his DIY electrical methods. He may also have some POS jury-rigged equipment. I find AFCI and GFCI technology great at catching sloppy or improper wiring methods.

Then again, there are those who believe a fuse blows because the fuse has a defect.

i dont know about this guy a goofy EI person seems that try to some silly things and try to tackle the wiring system himself is signing up a instant insurance canclation in record speed.

the way the EI describe the wiring system is way off the bat and dont have all the answer there.

the real electrician will spot this very fast there

right now i feel that there are too many DIY sites getting out of hand and we have to clean up their mess [ our good job sectury ]

Merci, Marc

p.s. i try be good person today by refraing my french swearing today

reno,

........"Then again, there are those who believe a fuse blows because the fuse has a defect. "

.....hahahahaha

the guy is his own hazard......after reading the rest of his explanations....it is now clear that he has no idea what he is talkng about....

..but a casual reader could think they have hit the MotherLode.......
and can have their housewired using ONE big circuit.

Mis-information always seems to outlast truth!

reno,
I couldn't agree more. Remember my topic in the OSHA forum (Qualified Electrician)? There are those of us that know trade practices and how to apply them, and then there are the imposters.

[This message has been edited by XtheEdgeX (edited 02-03-2006).]

Togol, would you mind providing a link to that site?

Roger

While I too think this guy is a poseur, I'll just address the issue of his (overly simplistic) view on motor starting current. A lot of power tools coming from overseas are now using 3 phase motors even if it is for a 1 phase service, and they build in an inverter to supply the motor with 3 phase. The inverters are inherently soft starting, so he may indeed have observed a starting current that low.

That said, I still think he is a dufus who has no real clue, posing as an "EI" to get attention. Too many of his other statements are dead wrong. He probably thinks motors only draw 200% current on start-up because he is measuring it with a Wal-Mart $9.95 VOM that is too slow to catch the peaks, and/or he has no idea how to switch on the peak reading feature anyway.

sure Roger, here it is...
http://forums.taunton.com/fw-knots/messages/?start=Start+Reading+%3E%3E

bring the popcorn......

Thanks Togol, I will try to find his post tomorrow.

Roger

Roger, for some reason that link opens a different thread...I hope this is it.....??

try this one.....this is the right one.....sorry
http://forums.taunton.com/n/mb/message.asp?webtag=fw-knots&msg=33694.1

[This message has been edited by togol (edited 02-03-2006).]

I went on the site and that guy is completely wacko! Its pretty funny to see someone right out there. LOL

He says that he is an Electrical Engineer. If his profession is in fact correct, its pretty scary.

RobbieD,
bet you didn't know 50A AFCIs were better than20A breakers?

bet you didn't know they even made 50A?

Togol, actually before this post I never even gave any thought to a 50A AFCI breaker being manufactured. You would have to be retarded to put bedroom receptacles on a 50A so why would they make them. LOL, I guess this guy didn't do any homework before he started to talk out of his A%%. Maybe next time people tell him he is wrong he will just wipe it and leave.

See, maybe 200A is just around the corner.....who can say ;> )

on the other hand if the NEC is really concerned about arcing faults...why not just put the bedroom circuit on a single element cartridge fuse ...maybe 8A forget all the fancy doodads...or require fuses in all corded appliances ?

..hell, fuse the bedroom Neutral while we're at it......is this the dumbest idea ever?

I saw a bumper sticker in D.C. yesterday that covers a lot of situations like this;
" If you make it idiot proof someone will just make a better idiot"

Aw geeze this guy is SPUN!!
I really like the part where he is saying to run a 40 or 50 amp circuit using # 6 "but #4 is better" for a string of receptacles??!!?!?!?! I wonder how you would attach said #6 or #4 to a receptacle???!?!?!?!!? Pigtails?? SURE...
( I cant stop laughing!!!)

Hmmm I wonder how then my friend's entire backyard metal / machine shop ran off an old 40A stove feed with #8 cable??? Never a voltage problem, rarely tripped the feeder breaker, rarely being 3x in as many years it was there, and that was only if the lights were all on, the welder was in use, air comp was running and someone started one of the other big pieces of equipment...

Makes me think back to where I was at that Retirement home when our company wired it..
The whole building was engineered and designed by what had to be all the engineers that failed and had a lack common sence, as in our case: " A non north facing photo eye used for control of outdoor lighting will fail to work at ALL" (agreed they work best when pointed north but they will operate pointed elsewhere).. but thats the least of the problems we had. ---->The feed to the kitchen run in 3" pipe with #3 copper conductors fused at 225A were of concern, but according to the engineer " Its ok as I am the engineer and I am always right"..... The list goes on.

A.D

that's my profession! But we are not taught things like electrical codes, or even things about overcurrent fault conditions and other safety issues. We get mostly theory in college. In my job I deal with milliamps or even microamps at 5V DC or lower voltage. Mostly limited energy so arc blasts are rare, and mostly low voltages so shock hazards are also rare. All good reasons why I can't get an electrician's license just by presenting my college BSEE diploma.... Different knowledge and skills needed for that.

wa2ise,
I hear ya. I will rephrase my remark.

If his profession is in fact correct,

"25 years as a professional engineer, practicing electrician, and code inspector in 5 states in the US"

Its still pretty scary! lol

[This message has been edited by RobbieD (edited 02-05-2006).]

I wouldn't get too scared just yet. As has already been pointed out, if he's buying 50A AFCIs, he's living in some sort of alternate reality. I understand that in alternate realities it's really easy to get college degrees, experience, girls, whatever you want. Heck, some of them even become dieties!

[This message has been edited by SolarPowered (edited 02-05-2006).]

From: decolores9 7:35 am
To: ALL (61 of 61)

33694.61 in reply to 33694.52

Quote-"This discussion seems to be deteriorating into personal attacks and arguing, so I'm not sure it's worth continuing the debate. I don't see any benefit in personal attacks, and don't want to stoop to that level.

However, I think there are some good points that have come out, or at least been hinted at, in this discussion:

1. If you aren't absolutely confident you fully understand NEC and your local amendments, seriously consider consulting an electrician.

2. In most municipalities, all electrical work must be inspected. Often, homeowners are permitted to work on their own homes without an electrician's license, but the work must still be inspected. The inspector is often a great source of information.

3. Get the work inspected. If you don't, you may be subject to fines. In addition, if you have a house fire, the insurance company can deny your claim because you have unpermitted electrical work. (it really does happen - a friend had his house burn to the ground, his insurance company denied coverage because a prior owner had done unpermitted work, unbeknownst to him. The courts upheld the denial). In addition, when you sell the house, many buyers will require copies of your permits and inspections. If you have to have the inspection done after the fact to sell the house, it will cost more and there will likely be fines.

4. Be wary of those who state they are P.E.s, but do not provide a license number, discipline, or comment on whether their post is an engineering report. It's a legal requirement in all 50 states, if one is issuing an engineering report. At least they are not following the legal requirements, and may well not be a P.E.

5. There is often more than one "legal" solution to a given wiring issue. I explained how I wire shops, and while others' attacked my solution, no one has proposed an alternative. I'm sure there are alternative solutions, but have yet to hear any alternatives to the options I proposed, that address the issues present in a shop. What I proposed is NEC compliant and safe, but there are likely other solutions. More importantly, your local inspector may like it, or not. It's best not to "fight" with the inspector - it's better in the long run to make the minor modifications they want to avoid antagonizing them, even if want they want is not required by NEC or local code. It's better to make friends than enemies of inspectors.

6. Use AFCI breakers - conventional breakers do not reliably trip in many cases. The exception, IMHO, would be a shop with a dedicated branch panel in which you turn off the main breaker when you are not in the shop. In that case, conventional breakers are OK - if there is a problem, you will be in the area to manually trip the main before a significant fire can develop. Keep the door to the panel closed, and try to locate the panel away from heavy dust areas, as dust - wood or otherwise - can contribute to the breakers "sticking".

7. Understand the practical wire size and current requirements for motor startup. NEC only requires one wire size larger for motors, but that is insufficient in most cases to prevent the voltage drop on motor startup (that's the primary benefit of using a 40A or 50A branch circuit - it solves the voltage drop and startup surge problems). Remember, too, that the LENGTH of the wire is critical in determining correct wire size. NEC has tables to use as a starting point.

8. Be cautious with any advice you receive on the internet. Many of the self proclaimed experts on this thread have a very flawed understanding of NEC, IMHO. The "majority" comment is often wrong - most people don't understand the subtleties of the NEC, or any other topic for that matter, but that doesn't stop them from attacking those who have a better understanding. Before you act on advice, confirm it with someone locally, whose credentials you can verify and whose authority YOU trust.

9. Use a GFCI in shop circuits - it may save your life one day. A GFCI receptacle will protect downstream receptacles, so it should be the first receptacle (i.e. closest to the circiut breaker). GFCI receptacles can be combined with AFCI breakers.

Thanks. I hope this helps."

LOL- This guy is funny.

RobbieD Gee I dunno 'bout him still..

This is my rebuttal to what he has to say, sorry I have to say it and get it off my chest..

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In points #2 and 3 about getting your work inspected.. If I wired my shop like how he did his, I am positive the inspector would kill himself LAUGHING while he walked out the door.. And in point #3, where your friends house burned down: did you give your friend some bad advice????.....

Point #5... We all know how to wire a shop properly.. There is no need to state an alternative as there is ONLY one way to do it... The CORRECT way ( weather it be bare minimum, or wired to the hills with extras, its the CORRECT way). You will not make friends with your inspector by wasting his time having him come out and find the whole place a hazard.

Point#6....
Use AFCI's???? Whats wrong with regular breakers??? If regular breakers do not trip "reliably" why do we use them by the millions in our houses to protect the wiring? Standard breakers work FINE! IF they are the right size for the conductor and load applied!
Want to keep them from sticking? Operate the handles once in a while like you are supposed to do to ensure the internals are not all bunged up, But I will agree keep it away from dust.. Common sence says that.. As for that thing about turning off the main when you leave, and being able to "shut the main off before a signifigant fire could develop"
Well if the branch breakers are sized CORRECT there will not be that problem, the breaker will trip!

Point #7: The voltage drop on motor startup.. Well generally one size "up" in wire gauge will work, heck its not going to hurt at all BUT but a 40-50 A branch circuit? FOR WHAT? I understand you need to upsize the conductor depending on its length to prevent voltage drop, but how far are you going in this case? the other side of a woodworking shop or across the street and down the block?? Also the overcurrent size would REMAIN THE SAME not be upgraded to something like 40-50A.. The starting current is MOMENTARY..

Point #8:
" Self Proclaimed Experts"... Well, Yes, Yes we are experts as this is our profession and we are liscensed or are in the process of doing so.. We do our work with pride and to the best of our ability following all codes and regulations to ensure a safe and neat installation or repair...
"Attacking those with a better understanding".... Who?? You? Better understanding of what how to wire a place to burn??? To be so unsafe the inspector is going to laugh himself to death as he walks out of the place?? Sure whatever!!

Point #9

GFCI's and AFCI's are not always compatible!! May seem like they are but not always, have had problems in the past doing this...
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Now I don't know guys, something about him saying things like the following really make me wonder about what profession he really is or if he just lacks common sence, or just thinks he hnows everything when in fact he is dangerous. Things said like:

1."40-50A circuit with multiple 20A receptacles"....
2. "Conventiomal breakers do not trip reliably"
3."turning off the main" or being able to "turn off the main before a signifigant fire could develop"...

Does it seem like he is just going in circles here or is this just me, sounds to me like he is saying: " upsize the wire, and the breaker, but have it feed a 20A receptacle, but use an arc fault because regular (read OVERSIZED) breakers will not trip should the motor short out.. OR use conventiomal breakers (read OVERSIZED again) and be present and able to open the main so that if a short develops, you can shut it off before the place burns to the ground, and shut the main off when you are not there in case something happens a fire will not result..."

Sorry people I nneeded a rant and rave today!

A.D