New central vac kicking breaker

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magictolight.com

magictolight.com

Senior Member
Location
Indianola, Iowa
Went on a warranty call back today. Have a nutone central vac system which is blowing a dedicated 20 amp circuit, one leg in a 3 wire circuit. Name plate full load amps is 12.5. 120 volt system. Square D Homeline breaker panel, 200 amp service. System draw 63.5 amps at start up and levels out at 10.5 amps, voltage drops from 120.5 to 117.5 and then stabilizes at 119 volts, GFCI receptacle is 25' from breaker panel on #12 stranded THHN. This is a cord and plug connected appliance. Vac has been tripping circuit 2 or 3 times a week for months now. Only tripped once for me, was on site early in the a.m. and probably had not run yet today. Tripped only on the first start and the other 10 or 12 starts ran fine. Was hoping that I could increase the amp rating of the circuit to accomodate the inrush but can't find a good spot in the code that will let me do it with a 20 amp receptacle, Article 210. Thought I might get away with cutting the cord cap off and hard wiring also. I hate the idea of hacking this thing together but I am at a loss. Any ideas?
 
goldstar

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I'm just going to take some wild stabs at this :

  • Is this tripping the breaker or the GFI receptacle ?
  • If it's the GFI receptacle, is ther a reason why you didn't just use a single receptacle dedicated to serving the vac ?
  • Try pulling out the breaker and examining it. The jaws might not be sitting properly on the buss bar. If it isn't you'll see burn marks on the end of the breaker.
  • If it's a MWBC make sure the other hot leg of the cable is landed on an opposing phase. If it isn't chances are you're drawing too much on the neutral
  • Find out what is on the other leg of the MWBC, clip your amp probe on the affected circuit and start turning things on and see what happens.

Aside from there being an intermittant problem that you'll probably never find, that's about all I can think of at the moment. Hope this helps
 
P

partimer31

Member
breaker tripping

breaker tripping

See if there anything printed that tell you the recommend size breaker
1) single pole 15 amp.
2) single pole 20 amp.
3) single pole 25 amp.

Now check the circuit breaker. Some breaker are only
rated as a, SWD, used with flourescent lights.
Now most currently avaible. No rating the breaker would
trip when you turn of the fluorescent light.

So pull out the circuit breaker any read its label, which may be printed
the load connection screw, printed just below the toggle, of the circuit
breaker. Siemens breakers and now rate SWD, Plus HACR

So I would want to make sure I had a HACR rated circuit breaker before,
I would question the vacuum cleaner. Also check for bad wire connections.
The HACR rate breaker allows a higher inrush current.

Good Luck
 
Last edited:
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
goldstar said:
I'm just going to take some wild stabs at this :
  • If it's the GFI receptacle, is ther a reason why you didn't just use a single receptacle dedicated to serving the vac ?
Click to expand...

If he's under the 2008 NEC there is no longer a provision for a single receptacle in lieu of GFCI protection for this circuit. Unless of course he was in NJ where this is still permitted. ;)
 
S

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
With that 65a inrush it should be 50a ckt. LOL
Go with Goldstar
Inrush could be 10x name plate.
How long (time) is the inrush? should be just a blip.
GFI or Vac smell funny, making sounds, low suction?
Plug an other 10a motor load, big drill see what happens.
#12 is 20a max......
 
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R

rwreuter

Senior Member
You know, if I was called out on a service call for this problem and I had checked everything out and could not find a problem I would change the breaker out and see if it returns.

Breakers go bad all the time.
 
magictolight.com

magictolight.com

Senior Member
Location
Indianola, Iowa
Inrush is only at start up. Circuit trips only at startup on the inrush. No option to hard wire.

What impact would a shared neutral on this circuit have?

Already confirmed the circuits are on a phase and b phase. Even if the neutrals were on a common phase it could overload the neutral and not trip the breaker.
 
A

AV ELECTRIC

Senior Member
I would guess this is a circuit pulled in conduit with stranded wire the breaker trips but not the gfci ime sure you tried another breaker. does most of the trips happen at startup ?Is this circuit on a afci? If there was a fault you would think it would trip the gfci so overload would be the next best guess. If the unit is rated for a 20 amp circuit and your wiring checks out and no afci your good its a warranty issue on the unit or intsall of the hoses like the others said a clogged hose could make the unit work harder. Explaining that to the customer is always fun you can plug something else that runs at higher loads for a period of time so the customer can see its not your install.
 
C

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
Does Homeline make resi breakers with different trip curves?

Have you called the vacuum manufacturer and explained the problem to them?
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Home-Line does manufacturer a SP120 with a higher trip curve., HOM120HM. I think that might be my first step.
 
S

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
I think I read when a vac is plugged it draws less; it isn't doing work in a vacuum . I was thinking a bearing or the insulation on the windings could be going.
If this is new call the vac manuf. and find what the inrush should be.
 
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