Panel replacement

Status
Not open for further replies.
G

Gary Dagley

Member
Location
Cedar Hill Texas
We have a customer that had her panel replace (not by us)

its a 100 amp sq d qo outdoor

we are quoting a new panel

100 amps is fine per the calculations

my questions is on the ac unit it has

FLA 27 amps but on LRA it's 135

I know on startup for a second or two it will pull up to 120 amps

so based on this should we upsize the panel?
 
You won't need to increase the panel size for the starting current of the AC unit. If the load calculations is 100 amps or less than that's all that you need.
 
Not for nothing, but why does she need yet another replacement panel of the same size?
 
The Buss is discolored and where the top four breakers are the buss is worn so the breakers are loose
we gave the customer the option to relocate the top four breakers as well as a quote for a new panel.
One of the main lugs is discolored as well
so we gave her the two options
 
Gary Dagley said:
The Buss is discolored and where the top four breakers are the buss is worn so the breakers are loose
we gave the customer the option to relocate the top four breakers as well as a quote for a new panel.
One of the main lugs is discolored as well
so we gave her the two options
Click to expand...

Hmmmm! Sounds like she has other issues. If the buss bar is discolored and a lug is sounds like something is getting to hot. I would track that down before I replace the panel. You don’t want to have the same issue with the new panel down the road.

I do not understand if the utility company runs 4/0 or bigger to the meter, why would anyone put in a panel smaller than 200 amps, people will always want to add something or remodel down the road.


Sent from my iPhone using Tapatalk
 
I would ask the customer when and why the current panel was installed. I suspect the original panel was experiencing the same problems as the current panel, which means she has a larger problem that the previous electrician never resolved!
 
Hmmmm! Sounds like she has other issues. If the buss bar is discolored and a lug is sounds like something is getting to hot. I would track that down before I replace the panel.
[/QUOTE
What do you think would cause a discolored bus bar? Heat. Most likely from loose breakers, poor continuity. Life of the product probally ran its coarse. Time and heat gradually took its toll on the bus bar. Would there be anything other than that?
It is a residential panel..loads aren't that heavy.
What else is there to track down..?
 
The main lug was loose
the buss looked like it had oil or a brown grease where the top three breakers attached one was a two pole 30 going to the dryer
the outlet for the dryer was replaced a few months ago due to loose connection
 
I'd go for a 200a service upgrade. The labor and materials are almost the same, and here, the POCO provides meter bases and their line-side work and materials free with upgrades.
 
Gary Dagley said:
The main lug was loose
the buss looked like it had oil or a brown grease where the top three breakers attached one was a two pole 30 going to the dryer
the outlet for the dryer was replaced a few months ago due to loose connection
Click to expand...
Square D plug-on breakers are all shipped with Plug-on Joint Compound factory installed on the jaws, but it is usually just a light film. Technically this compound should be replaced every time a breaker is removed and reseated.
 
Gary Dagley said:
back to my original question
100 amp outdoor panel
fed with #4 thhn good for 85 amps
ac unit inrush 120 amps for a few seconds
even just for a short time
Click to expand...

In my thinking I would change out the feed and panel to 4/0 and 200 amp panel, I believe this would solve the problem. 120 amps even for a short time builds heat and over a period of time wear down the components. It’s not worth getting a bad rep. over


“ shoot low boys their riding shetland ponies”
 
Gary Dagley said:
back to my original question
100 amp outdoor panel
fed with #4 thhn good for 85 amps
ac unit inrush 120 amps for a few seconds
even just for a short time
Click to expand...
For a 100 amp dwelling service the condcutors only need to rated at 83% of the servcie size so #4 THHN 85 amps at 75° C is code compliant. Again, not an issue with the AC starting.
 
Peter Furrow said:
What do you think would cause a discolored bus bar? Heat. Most likely from loose breakers, poor continuity. Life of the product probally ran its coarse. Time and heat gradually took its toll on the bus bar. Would there be anything other than that?
It is a residential panel..loads aren't that heavy.
What else is there to track down..?
Click to expand...

I’ve worked with panels a whole lot older then I am and none of them “ ran it’s coarse” something is wrong to discolor the thing. Just because it’s a res. panel does not mean it does not have a heavy load. You can run 18 amps on a 20 amp breaker and that’s a heavy load for that setup, but not on a 100amp breaker it’s all about you wire size you have and overload that will make a load heavy or not. And you track down “why is this happening”.


“ shoot low boys their riding shetland ponies”
 
Gary Dagley said:
The Buss is discolored and where the top four breakers are the buss is worn so the breakers are loose.
Click to expand...
Gary Dagley said:
We have a customer that had her panel replace (not by us).
Click to expand...

Can you tell how long it's been since the panel was changed and does it look like they also provided new breakers at the time?

I have seen some electricians around here that would do a panel change and use the old breakers.

If the panel isn't very old you may be able to just change out the guts and install new breakers as needed.
 
Gary Dagley said:
The Buss is discolored and where the top four breakers are the buss is worn so the breakers are loose
we gave the customer the option to relocate the top four breakers as well as a quote for a new panel.
One of the main lugs is discolored as well
so we gave her the two options
Click to expand...
I think you need to investigate this problem and not just replace the panel.
 
Gary Dagley said:
The Buss is discolored and where the top four breakers are the buss is worn so the breakers are loose
we gave the customer the option to relocate the top four breakers as well as a quote for a new panel.
One of the main lugs is discolored as well
so we gave her the two options
Click to expand...
Main lug might be because of poor connection, or even landing existing conductor into same lug that had been overheated the first time it was changed. This is even more critical you replace conductor or cut off the portion that was overheated with aluminum conductors but can still be a problem with copper.

Bus bars overheated, possibly reused the old breakers and if they had compromised breaker to bus connection in original panel they won't last long in a new panel.

Make sure you replace panel and all breakers on this one.
 
Status
Not open for further replies.
Top