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Old 04-03-2019, 09:23 PM   #21
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Quote:
Originally Posted by trentonmakes View Post
Nameplate said 240v. FLA 30

Guy I was with took the amp draw as maintenance guy started it up. Looking over his shoulder, it spiked to 50 for a second then held steady at 10..

Did it a couple more times and same readings. This is when I looked at the nameplate on the motor.

Only thing in the room was a disco and the compressor. Compressor did have a cutoff switch on it. I didn't notice anything else.

Motor was started several times while we were taking the reading. Motor/compressor is hooked up to the fire sprinkler system.

Maintenance guy took us downstairs, across the hall to where the panel was and pointed to a single pole 20a breaker marked compressor. He saod thays the one tripping at startup.

When we were in the van, I told the guy I was with, that couldn't have been the breaker because it's supposed to be a 240v motor. I wasnt going to bring it up infront of the maintenance guy.

I guess this is partly why I have been thinking about this, nothing seems right about any of it.





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Might be a breaker with the handle tie removed... Or the maintenance guy is a goof.
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Old 04-03-2019, 09:26 PM   #22
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Might be a breaker with the handle tie removed... Or the maintenance guy is a goof.
This is very possible!

I dunno who marked it, but panel said compressor 7 A-B

No clue what thats about

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Old 04-03-2019, 09:26 PM   #23
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Quote:
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Might be a breaker with the handle tie removed... Or the maintenance guy is a goof.
Dual voltage motor 480/240 fed out of 480v panel?
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Old 04-04-2019, 05:14 AM   #24
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Check to see if the SP breaker is being used for control voltage on the starter coil. Iv'e seen it done on r-mix plants more than once, but a NEMA 2 starter coil tripping a 20 amp breaker will not last long.
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Old 04-04-2019, 05:36 AM   #25
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It could be a 120/240 volt single phase motor wired for 120 volts.

I’m guessing it’s the jockey pump for a dry system? Breaker should be painted red and there should be a breaker lock on it so that it doesn’t accidentally get shut off.

Do they get a low pressure alarm through the fire alarm panel?
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Old 04-04-2019, 05:48 AM   #26
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It was probably a packaged unit with all the fire sprinkler stuff connected. That’s why there was a tag or whatever saying use #6 wire. It’s all pre-wired for 120 volts.
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Old 04-04-2019, 06:04 AM   #27
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Quote:
Originally Posted by HertzHound View Post
It could be a 120/240 volt single phase motor wired for 120 volts.



I’m guessing it’s the jockey pump for a dry system? Breaker should be painted red and there should be a breaker lock on it so that it doesn’t accidentally get shut off.



Do they get a low pressure alarm through the fire alarm panel?
Wouldn't the name plate say 120/240?


They said it was part of thier schedule so maybe a maintenance thing to avoid the alarm?

Definitely need to get more info on all this.

I'll find out today what's going on with this and if we're scheduled to go back or if someone else got it.

This company seems too bounce us around on jobs.

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Old 04-04-2019, 06:40 AM   #28
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Yeah check the name plate. If it’s a jockey/pressure maintenance pump they are usually 120v. I don’t think I’ve ever wired one for 240 or 208.

They probably never noticed a problem because normally the compressor never turns on. Now maybe they have a leak and the pump needs to run from time to time to keep water from entering the system. If a head pops the small pump is not supposed to keep up and then water flows.
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Old 04-04-2019, 08:33 AM   #29
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Apparently thos got pushed back until they call with an issue again.

Guess we'll be going back again in may

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Old 04-04-2019, 08:43 PM   #30
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If the full-load current actually is 30.0 amps, 240 single phase, it's a 7.5HP.

The starting current of this motor will be roughly 150 amps. On some meters, it's easy to miss the 1.

If this motor is supplied with 120, it'll produce maybe 15% of its starting torque and about 20% of its rated HP. It'll start fairly slowly with no load connected to the shaft. It will not start any sort of air compressor. I could possibly see the starting amps at 50 and 10 for running, again, with no load.

It's also possible that the single pole breaker has been installed in a 120/240 3Ø 4 wire panel on the high leg bus. In this case, it'll be operating on 208 volts. But both starting and running current are way low unless it actually is 150 amps and no load is connected.
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Old 04-04-2019, 10:59 PM   #31
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Come on T, you owe it to us to go back an take a picture of the name plate. We already have an unsolved mystery of buildings changing phase rotation from someone else’s post. Now this!!!

I have a question. How often are motors marked 240v. I was always told 230v rated motors were within the 10% of the rated voltage. So they will run on 208 to 240v. If it is marked 240v it shouldn’t be wired to a 208v system.

I was curious, so I checked the motors at the Baldor site. Most single phase were rated 120/230v. There were some rated straight 220v, but they were 50hz. There were none that I saw that were straight 240v. I didn’t check the thousands of motors at their site. Just a couple pages.

Also, was it possible that it was a Square D two pole breaker. The ones with a single space handle internally throwing both poles. I’ve seen guys put the covers on without breaking out the center strip of metal. Makes it look like a single pole in a way. They don’t make those panel covers anymore.
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Old 04-04-2019, 11:12 PM   #32
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He's either describing a jockey-pump or an air compressor for a tricked-out 'dry-pipe' fire sprinkler scheme. ( These are used for ultra-high value locations such as computer rooms that have to be shunt-tripped to kill the juice before the flood comes. )

The rest of the details just don't add up.
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Old 04-04-2019, 11:30 PM   #33
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Dry systems are common as dirt here. Not just for computer rooms but for the freezing temperatures. While most of the building would be a wet system, there’s usually a part that would get the dry system. Like under an awning at a store front, or some underground parking.
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Old 04-05-2019, 12:59 AM   #34
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Either way, such motors are tiny.

However, 240VAC could be expected.

For such tiny loads, ( <2hp ) single phase would be typical.
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Old 04-05-2019, 05:45 AM   #35
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I'll get the pic today. Lol

It could have read 220 and I just said 240

If it helps at all, this was in a senior center/complex

Condos/townhomes/assisted living.....


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Old 04-05-2019, 06:26 AM   #36
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Don't ask the customer anything, they have no idea. Get the nameplate, you usually don't get far without the nameplate info.

I know the usual voltage drop rule is a suggestion, but fire pumps have voltage drop requirements. The usual thinking regarding OCPD does not apply with fire pumps, the idea being it's OK to risk damaging the conductors if the building's on fire.

I would either

disregard everything the customer has told me, review article 695 carefully, and go over it with someone that knows their stuff

or

pretend it's a wrong number when this customer calls.

I do NOT want to be the last person that touched a non-compliant fire pump installation at a senior citizen's complex.

Sometimes with the time it will take to come up to speed on these things, you're better off letting someone that does a lot of this work have it. If you really don't want to share, and they're willing, subcontract them.
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Old 04-05-2019, 11:04 AM   #37
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I would not have expected a dry-type scheme in a senior center. They cost more.

This case gets stranger and stranger.
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Old 04-05-2019, 04:35 PM   #38
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Quote:
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Check to see if the SP breaker is being used for control voltage on the starter coil. Iv'e seen it done on r-mix plants more than once, but a NEMA 2 starter coil tripping a 20 amp breaker will not last long.
Ding ding ding! Winner! (In my opinion).

The motor is undoubtedly powered from a separate circuit, likely a 60A disconnect (minimum size of disconnect switch that will have a 5HP 230V single phase motor rating). 50A inrush on a motor with 30A FLC is nothing... it should be something like 180A or more, your meter may not be fast enough to catch it though.

The 1P 20A breaker is just for the control circuit, feeding the entire dry pipe control system in general. The end user doesn't really understand this, they just know that if you turn that breaker off, the compressor doesn't run.

The control circuit breaker is probably tripping because of one or more of the following;
A) there is a short in the contactor coil for the compressor,

B) the contactor is chattering

C) the main power for the compressor is causing a severe voltage drop on the system, the voltage drop then causes the control circuit to increase current.
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Old 04-05-2019, 06:44 PM   #39
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I guess I'm just imagining something much smaller. No starters.
Attached Thumbnails
Amp Spike On Startup-fire-pump-specs.jpg  

Amp Spike On Startup-fire-pump-specs-2.jpg  

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Old 04-05-2019, 06:57 PM   #40
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I guess I'm just imagining something much smaller. No starters.
Me too.

These puppies barely run as the system is tested to be air-tight in the first place.

Further, they are deliberately modest so that they can't hide the pressure drop of a popped head.

What do you bet that 5 hp turns out to be 0.5 hp?
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