Can I change 100 amp CB to 125
- Thread starter mlnk
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If the panel is rated 125 amps and allows the install of a 125 amp main then it is fine. The panel info should state what breakers would be compliant
kwired
Electron manager
- Location
- NE Nebraska
Factory installed main breaker may not have additional information on any labels related to changing that main breaker. They often only have information on branch breakers allowed.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Are you the utility then? You can't "upgrade the service wires" unless you are the utility, and if not they don't want you touching their side of the service. If they have provided a 100A service drop, you can't just arbitrarily increase that. They have to be consulted first.
ptonsparky
Tom
- Occupation
- EC - retired
Our POCOs are very responsive but I highly doubt they would change the size of their service drop solely because I upgraded a 100 to a 125. Maybe if I changed it to a 200 and told them we changed to electric heat. We are responsible from POA on in.
kwired
Electron manager
- Location
- NE Nebraska
Right.
Many will at very least want to be contacted if you are going to break the seal on the meter for any reason.
If you changed from even an old 60 amp service to a 200 amp service they may not change anything at all except for a new seal on the meter and new connectors at the service drop if your expected load hasn't changed.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
I would have assumed he meant the conductors on the customer's side of the service point.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
In doing so you will have increased the size of the service, which you should not do without consulting the utility. You don't know what size conductors are on their side of the meter, and most POCO's will have a problem with your breaking the seal on their meter can. You could be looking at a substantial fine for doing that.
Electrically speaking you might not have a problem; many utilities standardize their supply conductors to accommodate the largest service they will be asked for, but you still need to check with them. At the least they likely will want to send their own crew to break the seal and replace it after you change out the conductors from the meter to the service OCPD.
My mistake. I should have said Service entrance conductors.
Of course I do not change the service drop wires. That is poco job.
And I would be doing this with permit and poco permission.
The specs on panel say 125 amp rating. But do not say it is ok to remove factory 100 amp breaker and replace with 125. That is why I am asking the question.
kwired
Electron manager
- Location
- NE Nebraska
I would say it should be OK to put a 125 amp breaker in it then.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
In general, replacing a panel's OCPD is OK if it is accommodated by the design of the panel and it doesn't result in the OCPD being higher rated than the panel busbars.
kwired
Electron manager
- Location
- NE Nebraska
Problem may be somewhat a technicality though. Some panels with factory installed 100 amp main may only say 100 amps on any labeling, yet are built with same bus assembly as some that are marked as 125 amps.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Yes, you'd need to get it in writing from the manufacturer that the busbars are 125A if it's not documented in the panel.
We did get it directly from Eaton that their Cutler-Hammer panels from 150A to 225A all have 225A busbars. DISCLAIMER: Do not use anything I or anyone else on a forum says to make decisions that may expose you to liability. Get your own documentation.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Details matter. Some older breakers used a frame size that topped out at 100A, others at 125 and still others at 150. If yours is one of those that topped out at 100A, going to 125 means using a different frame size that may not be listed for use in that panel.
But to reiterate, if the panel says it is listed for 125A then yes you can use a compatible 125A breaker.
But to reiterate, if the panel says it is listed for 125A then yes you can use a compatible 125A breaker.
- Status