240.85 for my employer

[chris kennedy]

I recently did a job with a 120/240V Delta system that was incorrectly engineered. Had to order about a dozen straight 240V rated 2 pole breakers at around $100 each to correct the issue. I worked today with a different crew that made it painfully obvious to me that the owner of my company has been bad mouthing me behind my back about ordering these. Even though this is time and material and he got to mark these up 20%, he just has a hard time with this, same old crap, "Who else would care", "You think the EI is going to catch that?"

I would like to present him with the dangers of using a slash rated beraker on this system. (available fault current issues)

Little help please?

Thanks

 

[kwired]

I recently did a job with a 120/240V Delta system that was incorrectly engineered. Had to order about a dozen straight 240V rated 2 pole breakers at around $100 each to correct the issue. I worked today with a different crew that made it painfully obvious to me that the owner of my company has been bad mouthing me behind my back about ordering these. Even though this is time and material and he got to mark these up 20%, he just has a hard time with this, same old crap, "Who else would care", "You think the EI is going to catch that?"

I would like to present him with the dangers of using a slash rated beraker on this system. (available fault current issues)

Little help please?

Thanks

Well at very least ask him what happens if EI does catch it?

Is it then your fault and he is on your butt anyway if it fails inspection?

What are penalties from AHJ if corrections are needed?

 

[chris kennedy]

Is it then your fault and he is on your butt anyway if it fails inspection?

I'm not familiar with the statement "fail inspection".

You miss the point, this guy made at least $120 bucks off of my attempt to comply with .85 yet...

Just kills me

End of rant.

Thanks

 

[kwired]

I'm not familiar with the statement "fail inspection".

You miss the point, this guy made at least $120 bucks off of my attempt to comply with .85 yet...

Just kills me

End of rant.

Thanks

It is up to you to decide if you do what you know is right or if you do what keeps you employed. If you do what your boss wants you will be more familiar with the statement "fail inspection". You will then have him on your case for failing inspections, so keep doing what you have been doing is probably best for you.

Do you know for a fact that he wouldn't have made even more if you used regular breakers? Same price to customer either way means more profit for the less cost method.

 

[Rick Christopherson]

I would like to present him with the dangers of using a slash rated beraker on this system. (available fault current issues)

Danger and compliance are not the same here. It's not compliant, but the danger is no different.

 

[iwire]

Totally non electrical related but Chris, have you ever bad mouthed someone without really meaning any harm?

Its human nature, forget about it and move on, you were not meant to hear what he was saying so don't even worry about it. You did the right thing.

 

[jumper]

I am no breaker guy but it seems to me that it is just simple math.

A 120/240V breaker is only rated to clear faults at 120V for a fault on one phase or 240V phase to phase.

If a fault occurs on the high leg, 208V to ground, the amount of energy on that pole is going to be 1.732 times greater.

The breaker was not built or tested for that. It may fail, blow up, whatever.. instead or clearing the fault.

Say the fault current is 100A, at 120V there is 12KVA present, at 208V it is 20.8KVA present. Big difference.

Ask your boss if he wants to be responsible if a problem occurs. It was never tested that way, so it is a crapshoot on what would happen.

 

[boboelectric]

Sounds like poor engineering/estimating.

 

[augie47]

To thine own self be true

 

[chris kennedy]

Sounds like poor engineering/estimating.

Ya think? This set of plans was approved by the building dept, bid by our shop and handed to me. Get to job and verify the existing system..."Houston, we have a problem."

 

[jim dungar]

Ya think? This set of plans was approved by the building dept, bid by our shop and handed to me. Get to job and verify the existing system..."Houston, we have a problem."

Actually this looks very well thought out.

Over my career I have seen many panels like that one.
Order it factory assembled and it will come with the correct nameplate, but they will probably assemble it as a 'hybrid'. One section will be supplied with bus connections for Phases A & C only, whil the othe will be supplied with predominantly A-C only connections. Other than in the 3-pole spaces, you can use standard slash-rated 2-pole breakers.

 

[hillbilly1]

Ya think? This set of plans was approved by the building dept, bid by our shop and handed to me. Get to job and verify the existing system..."Houston, we have a problem."

Whats the problem? Just because every third row of track lights would be a lot brighter is a problem?:lol: The engineer even stated on the prints it was a 120/240 volt system!:lol:

 

[chris kennedy]

I built what I needed and the EE came to the site to pick up my as-builts. I never pointed out the problem to her, she was quite nice and we had the new design into the BD in 2 days. I ended up using 1 225A 42/60 1? panel, 2 225A 42/60 3? pnls and 1 125A 12/24 3? pnl.

 

[don_resqcapt19]

Danger and compliance are not the same here. It's not compliant, but the danger is no different.

Rick,
Are you saying that there is no technical reason for this rule and that both a straight rated breaker and a slash rated breaker can safely interrupt fault currents on a delta system?

 

[Rick Christopherson]

I am no breaker guy but it seems to me that it is just simple math.

A 120/240V breaker is only rated to clear faults at 120V for a fault on one phase or 240V phase to phase.

If a fault occurs on the high leg, 208V to ground, the amount of energy on that pole is going to be 1.732 times greater.

The breaker was not built or tested for that. It may fail, blow up, whatever.. instead or clearing the fault.

Say the fault current is 100A, at 120V there is 12KVA present, at 208V it is 20.8KVA present. Big difference.

Ask your boss if he wants to be responsible if a problem occurs. It was never tested that way, so it is a crapshoot on what would happen.

When in operation, the breaker has no idea what voltage the circuit is. The breaker sees virtually zero volts when it is closed. When its open, it's still going to see 120 volts across its terminals if its single pole, and 240 if its 2-pole. It still sees 240 volts between adjacent stabs. It's not compliant with 240.85, of course, but the danger is no different.

 

[jim dungar]

It still sees 240 volts between adjacent stabs. It's not compliant with 240.85, of course, but the danger is no different.

The problem is the Line to Ground voltage.

Some breakers do not have 240V to ground insulation, this saves manufacturing money. Some breakers vent their operating gases towards their line side connections, gas content and exulsion rate which may not be a problem at 120V can cause serious panel engulfing plasma events when misapplied on higher voltages.

 

[hillbilly1]

I am no breaker guy but it seems to me that it is just simple math.

A 120/240V breaker is only rated to clear faults at 120V for a fault on one phase or 240V phase to phase.

If a fault occurs on the high leg, 208V to ground, the amount of energy on that pole is going to be 1.732 times greater.

The breaker was not built or tested for that. It may fail, blow up, whatever.. instead or clearing the fault.

Say the fault current is 100A, at 120V there is 12KVA present, at 208V it is 20.8KVA present. Big difference.

Ask your boss if he wants to be responsible if a problem occurs. It was never tested that way, so it is a crapshoot on what would happen.

Never gave it much thought, but that makes sense. I did a quick search and found Bussman basically explains it the same way. But the thing is if a fuse is rated 250 volt, then it would qualify, but the AIC rating may be too low.

 

[Rick Christopherson]

The problem is the Line to Ground voltage.

Some breakers do not have 240V to ground insulation, this saves manufacturing money. Some breakers vent their operating gases towards their line side connections, gas content and exulsion rate which may not be a problem at 120V can cause serious panel engulfing plasma events when misapplied on higher voltages.

Yeah, I forgot about the venting near the deadfront. I had seen a nice graphic explaining it a couple years ago, but couldn't find it any more.

 

[kwired]

I am no breaker guy but it seems to me that it is just simple math.

A 120/240V breaker is only rated to clear faults at 120V for a fault on one phase or 240V phase to phase.

If a fault occurs on the high leg, 208V to ground, the amount of energy on that pole is going to be 1.732 times greater.

The breaker was not built or tested for that. It may fail, blow up, whatever.. instead or clearing the fault.

Say the fault current is 100A, at 120V there is 12KVA present, at 208V it is 20.8KVA present. Big difference.

Ask your boss if he wants to be responsible if a problem occurs. It was never tested that way, so it is a crapshoot on what would happen.

I won't say that any of this is totally wrong but want to make a few comments.

If breaker blows up it clears the fault, it is probably more desirable though to design and use one that will not blow up under the conditioins it is expected to be subjected to.

If fault current is 100 amps @ 120 volts that doesn't mean it will also be 100A @ 208 volts even on same system. You have same conductor, but you have different voltage as well as different source impedance as there will be more source windings involved in the 208 situation.

Just something to consider.

 

[Dennis Alwon]

Chris if my boss bad mouthed me-- she does :lol:-- behind my back I would confront him and let him know that you heard from other people what he was saying. Then explain why the AIC rating is important and don't forget to tell him his comments to others was unnecessary and unprofessional.