240 highleg to feed hot tub GFI ???

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rt66electric

Senior Member
Location
Oklahoma
I'm have a customer that is installing a 10kw heater and 3/4 cirulating pump to a steel tank, very similar to hot tub set-up. The installation calls for a 240v 50amp GFI diconnect for the heaters and a seperate 110 gfi for the pump.. The service is a 3 phase 240 wildleg setup with few 110 spaces to spare. Is it permissible to put the heater on the wild leg?? The the BR 2pole 50 amp breaker has a white pigtail and a white terminal lug. The pig tail is connected to the neutral bus, but the heater uses calls for 2poles . Will the gfi work properly ??
 
S

SEO

Senior Member
Location
Michigan
Some hot tubs require a neutral if that's the case your looking for trouble even if the breaker is a straight 240V.
 
2

220/221

Senior Member
Location
AZ
I don't understand the technical side of the GFCI but I thought it measures the amps on both legs and if they are not equal, it means something is going to ground and it trips.

I am probably wrong but if this IS the case, wouldn't the amps on the higher leg be less? No...I guess not. The volts to ground are different but they are the same across phases so....don't mind me...I am talking to myself.....again.


We have a lot of residential 3 phase deltas here and, to be safe, I NEVER use the high leg for ANY single phase load. I don't want to confuse some hvac guy, handyman or homeowner down the road.
 
jrannis

jrannis

Senior Member
Location
Fort Lauderdale/ Miami
Good Practice!
I try to keep the three phase seperate too.
Maybe the OP should setup a seperate equipment panel just for the three phase and put loads like this in a single phase panel.
 
mxslick

mxslick

Senior Member
Location
SE Idaho
The problem would most likely arise as the high leg voltage is unstable , as referenced to neutral.

So if the hot tub requires a neutral, depending on how things are wired internally, the high leg may end up feeding a load L-N which can result in a lot of bad things happening as well as upsetting the measured current balance from each hot to neutral.
 
Cavie

Cavie

Senior Member
Location
SW Florida
rt66electric said:
I'm have a customer that is installing a 10kw heater and 3/4 cirulating pump to a steel tank, very similar to hot tub set-up. The installation calls for a 240v 50amp GFI diconnect for the heaters and a seperate 110 gfi for the pump.. The service is a 3 phase 240 wildleg setup with few 110 spaces to spare. Is it permissible to put the heater on the wild leg?? The the BR 2pole 50 amp breaker has a white pigtail and a white terminal lug. The pig tail is connected to the neutral bus, but the heater uses calls for 2poles . Will the gfi work properly ??
Click to expand...


Answers=yes and yes.
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I guess it would depend on whether the tub 120 volt cir used the high leg rather than the other leg-- of course-doh. I believe one could figure which circuit is using the neutral and make sure that the high leg is not hooked to it.
 
C

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
They don?t make 240 volt GFCI breakers. All GFCI breakers are 120/240 volt. None of the supply houses in my area even stock standard 240 volt 2-pole breakers only 120/240. If I wanted to use the high leg for anything I would need to special order a breaker of use 2-poles of the 3-pole breaker. I?m guessing that the electronics of the GFCI would go up in smoke if you connected it to the high leg.
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
curt swartz said:
They don?t make 240 volt GFCI breakers. All GFCI breakers are 120/240 volt. None of the supply houses in my area even stock standard 240 volt 2-pole breakers only 120/240. If I wanted to use the high leg for anything I would need to special order a breaker of use 2-poles of the 3-pole breaker. I?m guessing that the electronics of the GFCI would go up in smoke if you connected it to the high leg.
Click to expand...

The DP gfci can be used as straight 240 volts or they can be used as 240 volt with a neutral connection.

I tend to agree that the unit may not function on the high leg- I would call the manufacturer for that info
 
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curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
Dennis, you can not use a 120/240 volt breaker on the high leg (208 volt) GFCI or not. You must use a straight 240 volt rated breaker.
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
curt swartz said:
Dennis, you can not use a 120/240 volt breaker on the high leg (208 volt) GFCI or not. You must use a straight 240 volt rated breaker.
Click to expand...

I can accept that -- so are you saying that there is a straight 240 GFCI breaker that does not utilize a neutral pigtail.
 
C

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
Dennis Alwon said:
I can accept that -- so are you saying that there is a straight 240 GFCI breaker that does not utilize a neutral pigtail.
Click to expand...

I highly doubt they exist. I have never seen a 240 volt rated standard 2-pole circuit breaker but they do exist. They may be readily available in some areas of the country where delta systems are more common but not in my area. Also we need to remember that most delta systems are open type and the transformer supplying the high leg is very small in comparison to the main transformer. The high leg is only supposed to feed a small portion of the load in the building such as the A/C. The majority of the load is supposed to be connected to the other legs.
 
Cavie

Cavie

Senior Member
Location
SW Florida
OP states 240 for heater (can you say no neutral) heater will not care about hight leg.
OP states seprate 120 circuit for pump. Pump will care about high leg. Stay away from it.
 
C

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
Cavie said:
OP states 240 for heater (can you say no neutral) heater will not care about hight leg.
OP states seprate 120 circuit for pump. Pump will care about high leg. Stay away from it.
Click to expand...

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.
 
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