Wednesday, August 2, 2017

Residential Basement Remodel Electrical

Client wanting a carte blanche project undertaken for a basement remodel

That was to have a full bath with a grinder and lift station for the sewage along with a kitchenette, bedroom and living room. Doing a visual inspection of the original 200 amp grid tied Main Breaker panel that was entirely filled with circurit breakers.
Along with a original 100 amp subpanel that was installed to the left of the Main Breaker panel that was also full of circurit breakers. A unsorted mass of wires that not only looks unsightly but also appears to be spliced with numerous wire nuts and other corrections that need attention. 

Hold on 1 more subpanel was discovered in the attached garage feeding electrical power to that area for lighting inside and out, outlets, switching as well as a 2nd story efficiency apartment with full bath above the garage. 3 total panels filled and more circuit breaker space that is needed for the basement remodel?  

Most DIY, handymen even licensed contractors may take the quick way out by using tandem circurit breakers which in the long run could become even more costly if over heating makes the wiring brittle.  The reason this style of circurit breaker produces twice the heat than a single pole circurit breaker of the same amperage rating. Simply put twice the heat is being put onto the same spot in the buss bar as well as the wiring . Personally I never take the quick fix,  quality craftsmanship and materials will always outperform and outlast minimum code requirements, substandard installations and every jacked up mess known to mankind.

The solution to this jigsaw puzzle was to remove the 100 amp subpanel reusing all original branch circurit home run wiring other than the cables that were feeding power power to the old subpanel that were to be replaced from the ungrounded SE U #2-3 cable that was using bare copper for a neutral. A new 24 space 100 amp subpanel was chosen to replace the old 12 space 100 amp subpanel, along with new PVC conduit that was to be used to refeed the new subpanel. All wire nuts splices need removed and relocated as necessary. 

The Main Breaker panel needs to be cleaned up removing all internal wire nut splicing and all circurit breakers relocated to the highest amperage and voltage closest to the main on down the buss bar. The reason for this relocation of circurit breakers in the main breaker panel is quite simple to explain as follows. Heat of any type rises upwards during the course of it's operation by having the 240 volt 100, 50, 30 and 20 amp circurit breakers all over the buss bar was making more heat than was necessary to the other 120 volt circurit breakers. A circurit breaker by design is made to operate by heat the more wattage that it controls the hotter that it becomes until it reaches its trip point or a dead short to ground if properly grounded. By taking the highest 240 volt amperage circurit breakers and placing them under the main breaker downward on the buss bar then makes a heatsink to dissipate the heat as rapidly as possible for efficiently if the wiring is installed correctly to do so. Remove and reroute any tandem circurit breakers as needed

Nothing can ever be easy when dealing with residential original wiring issues and this project was a classic example of this because the LB conduit body underneath the old subpanel had to be relocated also because the new 24 space subpanel was twice the size of the old subpanel. The obvious choice was to relocate the LB conduit body to the top of the new subpanel which meant having to pull the wiring out of that conduit raceway to be able to cut the original raceway as needed along with redrilling a new entrance hole. All these repairs had to be done before any new work could begin for all the new recessed light cans, outlets, switching, AFCI bedroom outlets, GFCI bath outlets. exhaust vent with light kit and all the other new wiring needed for the remodel.

All that still leaves numbers to be taken into consideration as total wattage load determines Main Breaker sizing.  Even with these 3 circurit breakers panels operating the Main Breaker is only going to take its amperage rating and then trip from overload. Before that even comes close to happening further testing 7 24 is needed on meter load side to original Main Breaker cables. to determine how much amperage and wattage is really being operated. Than that bridge can be crossed when those numbers are known? A grid tied original meter at 120 240 volt 200 amperage single phase is 48,000 watt (voltsXamperage=wattage) (wattage/voltage=amperage).

Personally I do not operate any Main Breaker to no more than 80% of its capacity leaving 20% in reserve for startup of motors, compressors, pumps and other large loads which require more voltage at startup. By doing this you see far less flickering in lighting. (200X80%=160). If the 7 24 load reports come back within those ranges than my next step would be to consider to upgrade the utility grid meter, weather head connections and necessary components for a larger amperage  to grid tied connection.

A to Z   D B Electric performs quality craftsmanship and services for clients.


Update Aug 3 2017

The task was 21 man hours and materials to do the heat sink step down method. Clearly shows the improvements completed. The original 200 amp Main had all piggyback breakers removed and transferred to 100 sub panel that was removed from 12 space and upgraded to 24 space. As well as placing each large 240 volt breaker highest amperage closest to the main breaker on down aka heat sink step down method . Allowing additional breaker space for basement walkout remodel electrical loads.  7 24 data loggers are gathering data for total current wattage usage more to follow after remodel loads are applied.