240 highleg to feed hot tub GFI ???

[hardworkingstiff]

Forget about the heater or any load. You can not connect a 120/240 volt rated breaker to a buss that has a voltage greater than 120 volts to ground.

Does anyone know why? I wonder if the 2-pole 120/240-volt breaker is made with the same parts as the 3-pole 240-volt breaker?

Is it really a breaker issue or is it just a way to not allow a non 3-phase load to be connected to the "wild leg"?

 

[jim dungar]

Does anyone know why? I wonder if the 2-pole 120/240-volt breaker is made with the same parts as the 3-pole 240-volt breaker?

Is it really a breaker issue or is it just a way to not allow a non 3-phase load to be connected to the "wild leg"?

The internal guts of the breaker are not made to handle much more than 120V to ground. It has to do with things like interphase insulation and the discharge path for gases created during the contacts opening. You want things cheap and dirty for the residential marketplace place, a manufacturers makes it 'less expensive' by not putting in parts that are not needed.

You can always connect non 3-phase loads to the high-leg simply by purchasing fully rated 240V 2-pole breakers.

 

[danickstr]

since no one ever knows how this stuff is wired internally I would definitely not use the high leg if there is a neutral going to the brains, 240 gfi or not. If the engineer that designed it randomly took power off of one of the "phases":wink: then we have no way to insure that future work on the panel would take that into consideration whether or not we do. I could see myself overlooking that point if I rebuilt the panel for them after this work was done. In other words, if someone had to rebalance the loads they could inadvertantly burn up the thing by swapping the UGC's going to the heater brain. Why dont they use gas?

 

[rt66electric]

smoke test update wild leg kills GFI

smoke test update wild leg kills GFI

WELL NOW we KNOW wild leg KILLs GFI breakers

a BR 2pole 50amp GFI breaker. (hot-tub)

Installed such a breaker on a job similar to hot tub. 3/4 pump on seperate 110 GFI. 10,000kw HEATER on 240 50amp GFI

DUE to limited # of empty breaker slots I pu the breaker on WILD_LEG B-C phase.

A-N 126v
B-N 209v
C-N 126v
A-B 246v
B-C 246v
C-B 246v

Installed 50a gfi breaker W/no load
The left lug or normallt A-phase connected to wild lg at 209 to grnd
The right lug or normally B-phase connected to C-phase 120 to grnd


When the breaker was energized with the handle still in the factory "TRIPPED" positon.--- all held normal

When the handle was reset and turned on-- it made that distintve sound--
ya-know the same as when a 120 motor is connected to 220..

HAD to go to PLAN B. replace breaker etc....

(or it could have been a bad breaker -probably not- I didn't want to gamble another $60 )

 

[rt66electric]

Hindsight

Hindsight

since no one ever knows how this stuff is wired internally I would definitely not use the high leg if there is a neutral going to the brains, 240 gfi or not. If the engineer that designed it randomly took power off of one of the "phases":wink: then we have no way to insure that future work on the panel would take that into consideration whether or not we do. I could see myself overlooking that point if I rebuilt the panel for them after this work was done. In other words, if someone had to rebalance the loads they could inadvertantly burn up the thing by swapping the UGC's going to the heater brain. Why dont they use gas?

I wasn't able to read your quote befor the smoke test. I agee with your line of reasoning. I considered about switching the high leg from right leg to left leg, but did not want to risk burning up the last breaker in the supply house. DENNIS

 

[220/221]

WELL NOW we KNOW wild leg KILLs GFI breakers

Thanks for reporting back. It is always preferable to learn from someone else's mistakes.