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Home > Home Wiring USA Archive: NEC 1999 > Short Articles > Wiring to Code (NEC 1999)

Wiring to Code (NEC 1999)

By Warren Goodrich
Wiring to Code (NEC 1999)

It is a lot like buying a computer. Buying the top of the line computer system, is outdated before you even buy it. Electrical code today also differs from the code of yesterday, yet the wiring of yesterday still exists, how can it considered safe before and not now? The only draw back from that outdated computer system is in performance, the draw back from improper electrical code, perhaps updated in some instances to experiences or tragedies of the past is more of a concern.

The minimum safety standards for electrical wiring changes and is rewritten often with as many as 1500 code changes every three years. Multiply 1500 changes in the way we wire every three years and you have around 20,000 changes in wiring design concerning safety over your 35 year period.

This does not say your wiring is unsafe. This says your wiring was outdated considering technology about 3 years after it was installed. While most of the changes in the NEC rules are minor changes every three years, many changes are life safety. This means accepted wiring design 35 years ago is now considered as unsafe.

The NEC however is set up so that a house wired 35 years ago if it met the NEC rules at time of original installation shall forever be governed and controlled by that version of the NEC active when it was originally wired.

Unsafe is the concern and important changes in technology is the second concern.

Examples 35 years ago GFI protection was just being introduced. Quality control of those GFI devices were not that good. We have learned a lot about GFI protection over those 35 years. The GFI protective device today is much more advanced and reliable that the GFI protective devices in that era 35 years ago.

Romex at that time era was rated 60 degree within the Romex cables. Today we have discovered temps in light boxes and attics are high enough to overheat that 60 degree wiring causing a safety concern to a minor level. What happened as discovered over the years is the wiring inside those light boxes got hot enough to make that insulation brittle due to ambient temperature inside the boxes.

Recessed light fixtures during that era was also just being introduced into the industy. What we didn't know over about a 4 year period of installing the recessed light fixtures of that era is that customers often increased the wattage of light bulbs in those tanks causing overheating which caused many house fires. After about 4 years we discovered this problem and UL required thermal switches to be installed inside the tanks so that the thermal will shut the recessed tank off when it reaches temperatures high enough to create an overheating concern and before these newer style recessed tanks can cause fire damage as the older tanks installed at the time your house was wired.

There are many other product changes and new product lines added that were not available at the time your house was wired.

To research your home look at the wiring overall condition. Take your two fingers and lay them across the cables periodically throughout your home. Look to see if you have plastic style romex or cloth style romex. This tells you a confirmation that your aging is correct as to how old your wiring is. If it is plastic Romex then chances are that wiring can not be over 45 years old approximately. If that Romex is clothe style that wiring was installed prior to 1955 approximately. 35 years ago the wiring pattern was mostly power to switch boxes with switch legs to light fixtures. 45 years ago wiring pattern normally ran power into the light boxes and ocopussed out to the receptacle going many different directions from those light fixtures. To test heat damage in your cables take your thumb and bend that entire cable in a "V" between your two fingers. This will tell you pliability of your older cables and if it was exposed to excessive heat. I predict you will find 35 year old wiring to be plastic Romex with power wired to receptacles and switches and seldom power in the light boxes being power in and power out. I also predict that if you do the bending to find brittle parts of wires that brittle wires will be inside the light boxes due to heat build up in those light boxes. If I am right and heat damage is contained to within the light boxes then this condition can be cured by installing boxes putting the older cables into the new junction box that is always accessible then running a new romex cable as a jumper from that light box to the junction box. The new cables are NM-B Romex cables that have a higher temp rating than the older NM Romex cable. Also check your light bulbs for wattage in excess of the fixture wattage rating stamped on the fixture.

Also at the time frame of your wiring receptacles were often back stabbed. Open all your receptacles looking for back stabbed connections. Check for brittle wires or damaged receptacle devices at point of back stabbing. The era of your wiring allowed backstabbing of receptacles for both 12 awg and 14 awg wires. It was discovered over years that the 12 awg wire stretched the sping connection clip of those receptacles causing the tensil strength to fail allowing for a loose connection. To cure this condition just cut off the heat damaged wire and connect the wires to the side screws. If the receptacle was damaged due to heat then replace that receptacle. 14 awg wire has a good track record with back stabbing receptacles and are still approved today. However the new receptacles today have a reduced back stab hole diameter to allow only 14 awg and not 12 awg wire in those back stab connections.

Recessed tanks that have no thermal protection can be easily disassembled from below the ceiling and taken out leaving the mounting bracket in the ceiling. Then buy the same brand light fixture sold today that has the thermal protection. Remove the mounting bracket from that new tank and slide that new tank into place through the ceiling hole and screw it to the old mounting bracket you left in the ceiling. This will update your recessed fixtures to new style recessed tanks that have the thermal protection. Then look inside the new tack to find wattage of bulb rating for each different type trim being used on that recessed tank.

There are other changes over the years as we learned from experience through records of fires and reports from inspectors and electricians. This is what prompts the NEC changes every three years. We monitor these reports world wide and when enough happens to cause concern that rule that is inadequately worded in the NEC then is changed in the next NEC version by ROPs of committees that work this data over the three year period between NEC versions. As soon as a new version of the NEC comes out we again immediatly start the process of making needed changes for the new version planned to come out three years later. This is an ongoing process. We learn as we react to what we learn. Wiring today is much changed over the last 35 years yet the wiring is much the same. The minor changes that we discussed in this article are the most known and most common of problems that concerned us over those 35 years.

Chances are the biggest part of your 35 year old wiring is still fine today. Some minor tweaking is often a good consideration as mentioned in this article.

Wiring properties can last for ages of many generations if not overheated or frayed or in disrepair. Problem is as we grow older we learn and invent. That learning and inventing creates a wiring condition that sometimes needs to be updated. 35 year old wiring is probably adequate in power available delivered safely throughout your home yet some items as mentioned above could use some maintenance activity.

This document is based on the 2002 national electrical code and is designed to give you an option, as a self-help, that should pass minimum code requirements. While extreme care has been implemented in the preparation of this self-help document, the author and/or providers of this document assumes no responsibility for errors or omissions, nor is any liability assumed from the use of the information, contained in this document, by the author and / or provider.

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