__._,_.___----- Original Message -----From: SpacemanSent: Thursday, July 26, 2007 5:14 PMSubject: Re: [papercreters] electrical -was- Re: modular blockAny conductor with current flowing through it produces heat. The amount depends on the amount of current and the resistance of the wire. For an extreme example look inside your toaster. Lots of current and high resistance produces lots of heat. The more thermal insulation you put around the conductor, the harder it is to dissipate that heat. That's why romex is run through cavities in hollow block, and other places where it can get rid of the heat.
I wouldn't worry too much about setting pc on fire except in extreme cases, but I would be concerned with the electrical insulation melting.
Spaceman
Neal Chabot wrote:Maybe a light fixture needs standoffs because of the heat from the light bulb?Maybe romex going through fiberglass, papercrete, cellulose, etc. doesn't needanything because it does not produce heat?Neal----- Original Message -----From: SpacemanSent: Thursday, July 26, 2007 2:50 PMSubject: Re: [papercreters] electrical -was- Re: modular blockBecause low density materials are generally good insulation, they tend to hold harmful heat in. As one example, a light fixture mounted on low density material has to have standoffs for air circulation, or be specially rated for the application.
Spaceman
Neal Chabot wrote:"There are special requirements for low density materials like papercrete"What possible requirements would those be?It seems to make sense that romex which is not rated for water be submerged in wet concrete.Neal----- Original Message -----From: SpacemanSent: Thursday, July 26, 2007 12:15 PMSubject: Re: [papercreters] electrical -was- Re: modular blockAnyone contemplating doing their own electrical work should get a copy of the NEC Handbook (and read it!). It includes the entire code, with illustrations, interpretations, and explanations. This makes it a lot easier to understand. Many professionals use the handbook as their main knowledge base. You don't even have to understand electrical theory or how to do calculations, it is all laid out for you. I'm not aware of any part of the NEC that is not based on safety, other than the administrative parts in the front.
There are special requirements for low density materials like papercrete, and for wiring in concrete. Hard to say which way an inspector would go, but it wouldn't be difficult to exceed both sets of requirements and be covered. For each wiring method there is a list of where it can and cannot be used. For instance romex (Type NM cable) cannot be used in any poured cement, concrete, or aggregate. So if you are slip forming, depending on your inspector, no romex. If you are using hollow core block, no problem. Heat is a definite concern since the wire insulation is thermoplastic and will soften and flow with excessive heat. I think the key to all this it getting pc into the IBC so we don't have to depend on inspector interpretations.
If your plumbing leaks you get a wet floor. If your electrical leaks your house burns down or someone gets hurt. Doing substandard electrical work is just asking for a problem. Most folks aren't aware of the ramifications of a major electrical fault.
The handbook is available in pdf format, and is searchable. Contact me off list and I will tell you where it is available at a very reasonable cost.
Spaceman
slurryguy wrote:Most of the electrical code isn't too bad. It's logial.
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