Yearly electrical debate thread

[Miriam C.]

We have a whole new group of very knowledgeable people giving information I thought I would instigate a debate.

The rules
All facts should be backed up by URL to knowledge base.
All opinions are welcome and please give examples of why you think it.

Please post your opinion only one time unless asked a question. I am pulling any insults to others opinions.

My opinion is that we all have our beliefs based more on what we experience than what is code or law and often we are more right than code or law. Mostly because code and law tend to catch up.

Subjects:

Best wire type, THHN Stranded or Romex (solid)

Stab in or Screw in receptacles and switches.

Lamp cord--(SPT) or (SJO)

Have fun! Shall I start?

I think Stranded wire is best for wire that must turn corners or be flexible. I also think it is best for screw type receptacles.

Best receptacles are those you install right. If you buy really good fixtures with stab in they have screw downs.

If you are limited to big box stores and the less quality then get the screw down type and be sure to install them right.

Lecture on quality fixtures= you are talking $4 to $5 each for good quality receptacles and the plates are 50 cents each. Not much if you are only buying a few compared to the expense of a fire because your cheap one screwed up.

BTW---anyone ever see a screw back out due to vibration.

[Micro469]

I thought you were a Moderator......Now you're an INSTIGATOR????

[Miriam C.]

I thought you were a Moderator......Now you're an INSTIGATOR????

Now I want real information without a fight and insults.

[PaulC]

I'm not sure about this, Miriam We all know what the Electrical Secrets section can be like. Be very careful

[48Rob]

Well...

Since there's some instigating going on...I'll add a bit of my own.

These kind of "informational" threads are good, as they allow the uninformed to become so.
The trouble with them, as Miriam pointed out, is how to know who has the "real" information, and who is just guessing, or worse yet, posting just to be posting...

Many times, it is pretty easy to tell who means well, but isn't quite sure about the info they're handing out.
They generally add an "I think" or "I'm pretty sure" to the beginning or end of their post.
Most would take this as friendly, though not necessarily accurate advice...

The other two groups though, the ones that really do know, and those who want everyone to "think" they know, are a bit harder to separate.

Qualifying ones statements is not a bad idea.
Doesn't need to be too technical, but yet easy enough for the average person to verify.

Of course at some point, a message board is probably not the place to seek critical electrical advice, but if we can self regulate to a degree, it can be most helpful to the general population.

It can be pretty frustrating to find 15 answers to a (serious technical) question that only two or three of the responders actually know anything about.
Why the rest post “I think” or “maybe I’m right, but I’m not sure” baffles me to no end…

Rob

[Larwyn]

Rob,

You are right. The ones that bother me the most, claim to be expert beyond question while giving out blatant miss-information. I have resolved not to waste any more of my time arguing with them on this forum, and others as well. I have been guilty of over qualifying my statements, or even presenting facts as questions, in an effort not to sound like the offending "experts". I've found that silence really is golden.....

[S. Heisley]

Rob wrote:

Why the rest post “I think” or “maybe I’m right, but I’m not sure” baffles me to no end…

...Sometimes, so they can find out if they are right or what the best answer is. A "maybe" statement can actually be a question in disguise.

[48Rob]

Hi Sharon,

I guess you're right, I didn't look at it that way.

If someone is asking, tying to find the answer, they would probably get a LOT more responses by saying something like; "I think this is the answer, but I'm curious, and hope someone who really does know will post".

Then there is no chance that others will interpret their answer as "I read it on the board, so it must be fact".

I suppose I'm blowing into the wind, tying to suggest that the information given on the board should be as close to accurate as the poster can make it...but I had to try...


Okay, now, in the spirit of Miriam's idea, can someone tell me what size power cord I need for my teardrop, and why?

Here is the relevant information;

I have a 20 Amp service inside.
The cord will be 75 feet long.

Rob

[Steve_Cox]

Okay, now, in the spirit of Miriam's idea, can someone tell me what size power cord I need for my teardrop, and why?

Here is the relevant information;

I have a 20 Amp service inside.
The cord will be 75 feet long.

Rob

I'm asking for it

Electric Power Research Institute (EPRI) helped to establish National Electric Code standards 120V AC electrification commonly referred to as "shore power" systems.

It calls for specific extension cord gauge and length—12 gauge for 15 and 20 amp connections, up to 25 feet in length, and 10 gauge for lengths over 25 feet—but are the right cords commercially available to RV users?

See I ended with a question, so I'm in the clear

[Miriam C.]

Gosh Rob, in the spirit of Miriam's debate the questions were asked for the debate.

The goal was to get a good cross view of those answers and why people believe that way. And maybe even get some real scientific reasons for those beliefs.

As for your question, you need to know if the power source is 12vdc or 120vac. I can't imagine it being 20 amps at 12vdc for a tD but stranger things are done here.

For 120vac need 12awg based on 3% voltage drop.
http://www.gorhamschaffler.com/wire_siz ... lator.html
This is a simple calculator for the normal person.

See the problem is more than one answer is right by industry codes.

Thanks so much for participating in good faith all of you.

7 responses and not one dealt with the debate questions. Perhaps a Poll?????????

[48Rob]

Oops...my bad...

I didn't read your post very well, I'm sorry.

I see now that you asked specific questions...

Maybe too late now, but I'll try the vibration question.

Yes, I've seen a screw in an outlet back out, but only partly from vibration.
The offending wire was in a travel trailer.
The outlet screw held aluminum wire, which expands and contracts with temperature changes.

Aluminum wire was used in houses, and trailers, both house and recreational from the mid 60's till roughly 1972.

http://www.wcgosman.com/repairing_aluminum_wir.htm

http://www.inspect-ny.com/aluminum/wirefire.htm

I somewhat disagree with the thought that "stab in" receptacles are somthing that should be promoted.
The reason is that while they work fairly well when the wire is installed correctly, too often the wire is NOT installed correctly.

It is very easy to stab the wire in the hole, and believe it is firmly seated.
There is a great deal of stress placed on the wire when the outlet, and the wire are being "worked" into the outlet box, where the wire can pop loose without being seen.

The outlet "works" for a while, but eventually gets hot from arcing, and smokes, or starts a fire. This can happen from the wire not being firmly seated in the beginning, or from being warmed too many times from a heavy load being placed on it, causing the spring tension against the wire to lessen.

Outlets that require the wire to be fastened with a screw, are better in that you can see the connection after the outlet is pushed into the outlet box.

Here is a link to one of many professional "opinions" regarding the use of these devices.
http://tinyurl.com/68toy7

Rob

[Rock]

First off - I was an electrical engineer in a former life and have been in a manufacturing environment for nearly 20 years. Still this is just my opinion based on screwing around with electricity for over 30 years.

Without exception, the wire used in the manufacturing environment is THHN. It is stranded with all the benefits that come along with that, and the insulation (polyester I believe - I have also been a plastics engineer for almost 20 years) is very tough, has a high temperature rating, is abrasion resistant and chemical resistant. Connections are always the screw or screw clamp type, and they rarely come loose even when subjected to machine vibration for years on end. It also comes in a variety of colors making color coding your project easy.

Romex being Romex (solid wire sheathed multi-conductor) does not seems to be the best choice. It's hard to pull in tight spaces, and being solid can fail (break) if knicked, especially when subjected to vibration.

Lamp cord is stranded but just - wimpy. It is stranded but typically doesn't have a ground, the insulation is soft and "sticky" making it hard to pull without damaging. I doubt the temp rating is anywhere near that of THHN.

An alternate option might be SO cord. This is pretty much what an extension cord is made of, but I doubt your typical cheap extension cord meets the requirements for "SO." Lengths of SO can be gotten at my home center.

As long as a AC receptacle is installed right there should be no issues. I've wired plenty in houses and always use the screw terminals. I also tend to buy the higher quality receptacles. There is a huge difference between the 29 cent cheapy and the $10 commercial receptacle. As long as the screws are torqued to the specification (I have a calibrated hand there should be no issues.

JMHO.

Eric

[Arne]

This is copied from another thread, but it belongs in both places:

------------

One thing not mentioned enough, is mounting of the wire. I used romex in the ceiling because it was sandwiched into foam insulation. It can't move, so I'm not concerned about vibration.

If you look at page 10, second picture of my link, that is the longest stretch of wire not clipped and screwed. Notice that all wires have been taped together for strength.

How you mount/restrain the wire is just as important as the type of wire you use.

Regarding nicking romex (solid wire)... that certainly can be a problem. Referred to as 'notch sensitivity'.

I would never use 'push in' connectors (wire pushed into receptacle). I do not believe they come close to the surface area contact that a screw head provides.

[jss06]

:BTW---anyone ever see a screw back out due to vibration.[/b]

Not when you use thread lock on the screws.

[Miriam C.]

:BTW---anyone ever see a screw back out due to vibration.[/b]

Not when you use thread lock on the screws.

No NO nO Thread Lock is highly flammable.





http://www.everbuild.co.uk/images/pdf/c ... k%20gp.pdf

I want to say "here hold my beer."

Try this instead
http://tinyurl.com/6fdu92