Overloaded fuse box, multiple tapping and knob and tube wiring

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Electrical inspection uncovered overloaded fuse box, multiple tapping of the mains & branch circuits resulting in an extreme hazard
Click this picture for a closeup
This is a very old fuse box found on a recent inspection.  There is multiple tapping of the mains, the branch circuits, and was likely overloaded.  This is a multi family dwelling with additional circuits had been added over the years (we found that there were 2 other fuse boxes connected through this one).  Knob and tube wiring throughout the dwelling was an additional issue that needed to be addressed.

We recommended that a electrician evaluate this service, and was an extreme hazard. 

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Mutiple Tapping of Breaker
Click the picture for a close up Our electrical inspection turned up several double triple and this quadruple tapped breakers, with different gage branch circuit wires
This panel had several double triple and this quadruple tapped breaker, with different gage branch circuit wires. Recognizing these hazards are critical to you and your families safety

Double  tapping

Multiple (Double or more) tapping is connecting 2 or more wires to a connection designed for 1 wire. This can create hot spots if not tightened to the correct torque and especially if two different size conductors are used. Because the hot and neutral wires are current carrying conductors, the chance is then greater for potential hot spots. 

If the double tap becomes lose, it begins to arc.  If there is a hot spot, this heating and cooling of the connection can loosen it.  As it arcs it builds up carbon. Carbon increases the resistance and with more carbon buildup the more difficult it is for the conductor to make contact....thus increasing the current. 

End result can be the breaker tripping because of the loose connection (excessive current exceeding the rating of the breaker), or signs of overheating such as discolored wires, melted wires, etc, or fire.


Knob and tube wiring

Knob and Tube Wiring
Click the picture for a close upknob and tube wiring slpiced to NM cable hazard  
Knob and tube wiring in an attic, with NM cable spliced to it. This circut was not designed to carry the extra load newer wiring may demand. All these junctions should be made in an enclosed box
Knob and tube wiring was the earliest standardized method of electrical wiring in buildings, in common use from about 1880 to the 1930s.
Some problems include

- No safety ground conductor;
- Sometimes switching of the neutral conductor
- In-line-splices in walls without using an accessible junction box
- Often overloaded as new circuits added over time
- Insulation is less resistant to damage, has a lower temperature rating, and it less water-resistant

Older homes may have knob-and-tube wiring for all or part of their electrical system. Such wiring systems may require replacement and modernization, as they are generally inadequate for modern levels of power use. 

Knob-and-tube wiring may have been damaged by renovations done in the building over the years, its wiring insulation may have become dried-out and brittle, or it may have been damaged by rodents or carelessness (for example, hanging objects off wiring running in accessible areas like basements).  Most lighting fixtures will have brittle insulation as they age due to higher wattage and heat of modern light bulbs.  Many originally had 40 watt bulbs, when was the last time you saw one that small in a room lighting fixture?  The excessive heat from a modern light fixture can cook the insulation off, since this wiring had a much lower tolerance to high heat conditions.

 See our Homeowners Library for more valuable information

Seattle Area ASHI Home Inspection Team
Serving Seattle, Tacoma, Everett Olympia and all of King, Snohomish, Pierce, Thurston Counties