Upgrading breaker in existing generator - UL listing question

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anbm

Senior Member
10 years plus old - outdoor emergency generator, if we want to change out the existing main breaker with a higher amp. rating breaker (still comply with code for protection), will this void any kinds of generator's UL listing, warranty? The warranty may be not a factor since the generator is 10 years old I guess. Thank you.
 

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
Why do you want to put in a higher amp breaker? The breaker that came with the generator is probably the highest amp breaker it can handle.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
The installed breaker was undersized.
And you know that how?

In response to your question however, ANY change you make to a piece of UL listed equipment technically violates it's UL listing. So the question is really, what does THAT then mean to you? UL listing is important at two times:

First, when you install something and the AHJ wants to see an NRTL listing on it. If it's already installed and not going to be inspected, what does it matter?

Second, IF there is a fire and your insurance investigator discover an alteration of the listed system and can attribute the cause to that alteration, the carrier may decline coverage of the loss.
 

topgone

Senior Member
And you know that how?

In response to your question however, ANY change you make to a piece of UL listed equipment technically violates it's UL listing. So the question is really, what does THAT then mean to you? UL listing is important at two times:

First, when you install something and the AHJ wants to see an NRTL listing on it. If it's already installed and not going to be inspected, what does it matter?

Second, IF there is a fire and your insurance investigator discover an alteration of the listed system and can attribute the cause to that alteration, the carrier may decline coverage of the loss.

Thanks for reminding about the cold facts!
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
Second, IF there is a fire and your insurance investigator discover an alteration of the listed system and can attribute the cause to that alteration, the carrier may decline coverage of the loss.

After hearing it for years, and never seeing it happen, it finally happened to us.

We are named as defendants in a lawsuit right now against an insurance co. that doesn't want to pay out for fire damage to a customers premises. The customer is on our side and has been one of our most loyal customers for YEARS.

In any case, I don't think it's going to end well.

Insurance companies are in this to collect premiums, not pay claims. As such they have a team of lawyers at their disposal.

You better be 100% before you change that breaker. Personally, I would only do it with a document from the generator manufacturer giving us their blessing.
 

anbm

Senior Member
I'd be comfortable knowing the original breaker size.

480V/3PH, 100kW gen. set, @ 0.8 pf, old main breaker rating is 125A/3P,
plan to change out to 175A/3P, thermal magnetic CB. Make sense? Existing
wires are good with 175A rating (2/0).
 

ron

Senior Member
UL 2200, the Standard for Safety of Stationary Engine Generator Assemblies, was first introduced in 1998 and many generators are sold / installed without a listing, even today. Granted it is more likely that it is if it is an Article 700 or 701 gen, but even then some AHJ's do not require it.

It is very possible that the generator is not listed as an assembly, so you can replace the CB with the concern of messing with a listing if it isn't listed. So you should try to look to see if it is listed under UL2200.
 

RumRunner

Senior Member
Location
SCV Ca, USA
Occupation
Retired EE
After hearing it for years, and never seeing it happen, it finally happened to us.

We are named as defendants in a lawsuit right now against an insurance co. that doesn't want to pay out for fire damage to a customers premises. The customer is on our side and has been one of our most loyal customers for YEARS.

In any case, I don't think it's going to end well.

Insurance companies are in this to collect premiums, not pay claims. As such they have a team of lawyers at their disposal.

You better be 100% before you change that breaker. Personally, I would only do it with a document from the generator manufacturer giving us their blessing.
Cow​
The bum steer could sway someone to the dung heap. :)


The circuit breaker that comes with generator is meant to protect the conductors that deliver power to the intended load.​
Not intended to protect the generator itself.


OP stated that the wire 2/0 is good for 175 Amps.. . . and it is-- according to NEC Tables.​
Clearly, based on the output power of the generator-- which is rated 100 kW-- the max current that will go through these conductors (not even considering the power factor of .80 ) is far less than the 2/0 wires can handle.


100000/460*sq rt 3=125.65​
If we apply the .80 power factor--we would come up with 100 Amp current that will travel through the wires at full load. Much less than the wire ampacity.


Changing the breaker from 125 Amp to 175 Amp would not cause fire.

Here's why:


Most consumer type generators are the closed loop model that are equipped with self-excited field rotor. When I say self-excited it means no independent source for excitation.
In the event that overload or short circuit occurs-- the output of the generator will bog down and stop due to the collapse of the excitation voltage to the field rotor.


Without excitation power to the rotor --no voltage would be generated to cause fire.


This is one reason why NEC won't even bat an eye regarding "oversized" circuit breaker.
As long as the electrician is in his right mind and would not attempt to install a protective device that will exceed the conductor ampacity, AHJ won't give a damn.​
Look it up in Art 700 if you find any restriction.


If what you are saying here were to be trusted. . .you need a good Electrical Engineer as expert witness that will take the stand and your attorney--that this is more than just a play of legalese.



This is more science and common sense than anything else.


You need your attorney to explain this to the jury (or judge). . . and even your knowledge of the electrical trade would help.​
Attorneys are not engineers.


I'm not an attorney but I've been in lawsuits similar to this. . . not that I've been sued.


My hands are clean. LOL
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
Cow​
The bum steer could sway someone to the dung heap. :)


The circuit breaker that comes with generator is meant to protect the conductors that deliver power to the intended load.​
Not intended to protect the generator itself.


OP stated that the wire 2/0 is good for 175 Amps.. . . and it is-- according to NEC Tables.​
Clearly, based on the output power of the generator-- which is rated 100 kW-- the max current that will go through these conductors (not even considering the power factor of .80 ) is far less than the 2/0 wires can handle.


100000/460*sq rt 3=125.65​
If we apply the .80 power factor--we would come up with 100 Amp current that will travel through the wires at full load. Much less than the wire ampacity.



A 100 KW genset @ .8 PF is 150 amps.
 
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