480 V panel for 208 V service

[SunFish]

Any code or functionality issues with using a 480 V rated breaker panel on a 208 V service?

Breaker panels have ridiculous lead times right now. I recently found someone that can provide a panel in slightly shorter lead times, but they only build 480 V panels.

 

[LarryFine]

Not an issue.

 

[ggunn]

Any code or functionality issues with using a 480 V rated breaker panel on a 208 V service?

Breaker panels have ridiculous lead times right now. I recently found someone that can provide a panel in slightly shorter lead times, but they only build 480 V panels.

Not a problem as long as the current ratings are sufficient for your needs, but once I got deceived by equipment used this way. I designed a PV system for a 480/277V service that turned out to be 208/120V. Lesson learned: ALWAYS check the voltage; don't just look at the equipment nameplates.

 

[electrofelon]

On a recent order of 208/120 factory siemens panelboards, some of the breakers supplied were BQD's (their typical 480/277 breaker) instead of the typical BL's. The branches were spec'd at 22KAIC instead of the usual 10, so maybe they were out of some of those as they are less common so provided the BQD's instead. Whatever the reason, there is no issue.

 

[Carultch]

Not a problem as long as the current ratings are sufficient for your needs, but once I got deceived by equipment used this way. I designed a PV system for a 480/277V service that turned out to be 208/120V. Lesson learned: ALWAYS check the voltage; don't just look at the equipment nameplates.

I feel your pain. Your initial site visit team is probably not equipped to take panels apart and work energized. Then you plan everything on the assumption of 480V with no data to tell you the actual situation. Also frustrating when a dead front covers the identity of a breaker, so you can't investigate its specs in more detail.

Seems like a situation that should require field-installed markings.
"If distribution equipment has a nameplate voltage rating exceeding 120% of the largest nominal voltage rating present within the system, the enclosure shall be field-labeled with the nominal voltage of the system, in a location visible without exposing live parts."

The 120% number allows the status quo for 208V systems using 240V equipment, where other clues likely tell you this information. Probably a good idea to label it anyhow.

 

[ggunn]

I feel your pain. Your initial site visit team is probably not equipped to take panels apart and work energized. Then you plan everything on the assumption of 480V with no data to tell you the actual situation. Also frustrating when a dead front covers the identity of a breaker, so you can't investigate its specs in more detail.

It's more painful than that; the initial site team was me and one other guy; it was one of the first commercial site assessments I participated in. There were eleven sites in this project and all the services used 600V switchgear, but only this one was a 208/120V service. All the rest were 480/277V. Checking the voltage never occurred to me at the time, but it certainly does now.

 

[winnie]

BQD's (their typical 480/277 breaker) instead of the typical BL's. The branches were spec'd at 22KAIC instead of the usual 10, so maybe they were out of some of those...

Many breakers have different KAIC ratings at different nominal voltages. Eg the same breaker might be labeled 14KAIC at 480V and 65KAIC at 240V.

This is relevant to the OP: if you are using 480V equipment at 208V, and you need high KAIC ratings, don't pay extra for the 480V high interruption rating, because the equipment probably has a huge 240V or 208V rating already.

Jon

 

[electrofelon]

Many breakers have different KAIC ratings at different nominal voltages. Eg the same breaker might be labeled 14KAIC at 480V and 65KAIC at 240V.


Jon

Yeah IIRC, that's exactly the ratings on the BQD's. They do make a 65k 240 breaker, not sure how price and availability compare to a BQD which is 65k at 240.

 

[pv_n00b]

It's more painful than that; the initial site team was me and one other guy; it was one of the first commercial site assessments I participated in. There were eleven sites in this project and all the services used 600V switchgear, but only this one was a 208/120V service. All the rest were 480/277V. Checking the voltage never occurred to me at the time, but it certainly does now.

I ran into a 480V service SWBD once where the service voltage was actually 460V. Only one I have ever seen. Luckily there was a sticker that had in big red letters "460V".