Originally Posted By: Ben Gromicko This post was automatically imported from our archived forum.
Today I inspected a house with an overhead 200-amp main electrical service line entering the electrical meter box. The 200-amp line continued from the meter to the house electrical panel box. All well.
However, when I inspected the main electrical disconnect, it was labeled 150-amps.
What da F?
-- Benjamin John Gromicko
Vice-President,
PEACH Inspections
NACHI & ASHI Member
Originally Posted By: rwills This post was automatically imported from our archived forum.
The actual rating of your electrical service is determined by the smallest of three components (service cable, electric panel and disconnect). A 200 amp service panel with a 150 amp disconnect main breaker and a 100 amp service entry cable means the actual electrical service to the house is only 100 amps, no matter what the panel or main breaker have imprinted on them. Unfortunately, this type of situation is all that common, especially among DIY’s, and represents an extreme hazard. The main breaker won’t trip until the flow of electricity has reached 150% of the service entry wires capacity. The results could be catastrophic.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
Bob,
Would that not be two components since the disconnect (main breaker) should have the same rating as the panel? I do come accross some panels that are "made" but typically you see those is commercial installations. Making an electrical panel from parts would be too complex for the average DIY'er. I think you are seeing the wannabe. He is really a small electrician that want to be a big player. I have also seen electrician use left over parts from other jobs to make residential panels. This is not really a bad thing if he knows what he is doing, just be certain all the breakers are labeled with the proper ampacity rating. I see quite a few older ones which are faded or missing entirely.
Originally Posted By: rwills This post was automatically imported from our archived forum.
Joe, Normally it should be two components but you’d be surprised at how many main disconnects I’ve seen that don’t match the panel for whatever reason. Most people think the main switch idicates the service amperage and for the most part are right but don’t be fooled! I learned the formula above from past courses I have taken and noticed that several other HI’s also use it. It probably applies mostly to older services that have been altered over the years by God know’s who.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
Hey Bob,
Thanks for passing that information along to us. It was nice to know somebody stayed awake in Electric 101, God knows I could'nt.
I do not come accross that very often and usually not even the breakers in the panel are the same brand which is a dead give away.
Since I worked in the electrical industry for 5 years I know they can not be trusted and always read the main breaker amperage and disregard the panel rating altogether. Your way would certainly come close to me in that regard. I think you did a much better job of explaining it.
Originally Posted By: dedgren This post was automatically imported from our archived forum.
Today I inspected a house with an overhead 200-amp main electrical service line entering the electrical meter box. The 200-amp line continued from the meter to the house electrical panel box. All well If the service entry cable is oversized relative to the service disconnect , that is not a problem.
Originally Posted By: jfarsetta This post was automatically imported from our archived forum.
Bob’s correct, Ben. What you described is okay (although should be noted) , so long as the heirarchy of wire sizes is not reversed. This meand that a 150 amp breaker can be fed via 200amp rated cable, but a 200 amp breaker can NEVER be fed via 150 amp rated cable
Originally Posted By: jfarsetta This post was automatically imported from our archived forum.
a defect. Should the homeowner ever decide to upgrade their service to 200 amps, they save money by not having to change the drop wire or, hopefully, the meter pan. Like Nick says in his “What Really Matters” verbiage, many things we observe are things that are “nice to know”. This is nice to know. Same as having all branch circuits wired with #12 when #14 is good enough. It’s just nice to know. If you choose to bypass it in your report, that’s cool. Nuttin’ wrong with it. It’s certainly not required.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
Joe F.
Thanks for the information, I thought I was sleeping again in Electric 101 when the teacher actually said something important!  HE HE
