a question about multiple motors on the same starter...

[iwire]

How do you interpret:

He was, in my opinion, counting on a single overload device to provide the OCP for all the motors. Others seem to read it the same way and the OP has not disputed it.

But this is a foolish discussion considering the OP is alive and able to jump in here.

 

[Besoeker]

He was, in my opinion, counting on a single overload device to provide the OCP for all the motors. Others seem to read it the same way and the OP has not disputed it.

I took:

protection ......... for each individual motor

to mean protection for each individual motor.
I can't see how it could be interpreted in any other way. Of course he might have stated it that way but meant something else.

But this is a foolish discussion considering the OP is alive and able to jump in here.

Quite so.
Come in mr biker...

 

[iwire]

I took:

to mean protection for each individual motor.
I can't see how it could be interpreted in any other way. Of course he might have stated it that way but meant something else.

Well here is the thing, he seemed to be planning to run a single set of 8awg cable for all five motors. Given that I don't see how he would have been doing individual overloads for each.

 

[augie47]

Pending correction by the original poster, I would have to say I read it the same as iwire.
Having never seen a 3 HP 3 phase motor with internal overload protection and from reading the OP, I also thought he was planning on one OCP device sized based on the total load of all motors.

 

[Besoeker]

Pending correction by the original poster, I would have to say I read it the same as iwire.
Having never seen a 3 HP 3 phase motor with internal overload protection and from reading the OP, I also thought he was planning on one OCP device sized based on the total load of all motors.

But

for each individual motor

Don't see how that equates to one total.

Ignorant Brit strikes again........

 

[iwire]

But


Don't see how that equates to one total.

He is, like me, an electrician first and a student of good writing much further on down the line.

Are you going to OK?

 

[iwire]

looks like i'm gonna end up bidding it as a nema 1 box large enough to handle
5 din rail 3 phase fuse blocks, 5 din rail starters with running overcurrent protection,
5 disconnects up on the roof, i can feed all of them with one set of #8 wires on a single
breaker, and put the box on a column in the center of the building, so it limits the
length of the individual motor leads. i'll run individual 1/2" emt to each motor, with #12 in it,
not on the roof, without j boxes in the runs, just transitioning to GRC to penetrate
the roof, with a transition to sealtight, going to the disconnect. i'm looking at using
motor rated switches inside the mushroom fan housings. i can mount the T stat controlling
the whole thing on the nema one box, and call it good. i could use MC cable for the motor
leads, but that would just look cheezy, imho.

is there anything else i have to derate for, like the political situation in the middle east?

btw, thanks for the feedback.

I know I am not on your Christmas card list but none the less I will toss this out.

Your above plan means you are intending on making a 'Industrial Control Panel' as such you will have to follow the requirements in article 409.

Here are the biggies

409.110 Marking. An industrial control panel shall be
marked with the following information that is plainly visible
after installation:

(1) Manufacturer?s name, trademark, or other descriptive
marking by which the organization responsible for the
product can be identified.

(2) Supply voltage, number of phases, frequency, and fullload
current for each incoming supply circuit.

(3) Industrial control panels supplied by more than one
power source such that more than one disconnecting
means is required to disconnect all power within the
control panel shall be marked to indicate that more than
one disconnecting means is required to de-energize the
equipment.

(4) Short-circuit current rating of the industrial control
panel based on one of the following:

a. Short-circuit current rating of a listed and labeled
assembly

b. Short-circuit current rating established utilizing an
approved method

Informational Note: UL 508A-2001, Standard for Industrial
Control Panels, Supplement SB, is an example of an
approved method.

Exception to (4): Short-circuit current rating markings are
not required for industrial control panels containing only
control circuit components.

(5) If the industrial control panel is intended as service
equipment, it shall be marked to identify it as being
suitable for use as service equipment.

(6) Electrical wiring diagram or the identification number
of a separate electrical wiring diagram or a designation
referenced in a separate wiring diagram.

(7) An enclosure type number shall be marked on the industrial
control panel enclosure.

Are you ready to do all that?

Here is my thought and it is radical.

Purchase five correctly sized enclosed magnetic motor starters a piece of wireway and put them together. Don't forget these are motor controllers and require a disconnecting means in sight of them.

430.102 Location.
(A) Controller. An individual disconnecting means shall
be provided for each controller and shall disconnect the
controller. The disconnecting means shall be located in
sight from the controller location.

Exception No. 1: For motor circuits over 600 volts, nominal,
a controller disconnecting means capable of being
locked in the open position shall be permitted to be out of
sight of the controller, provided the controller is marked
with a warning label giving the location of the disconnecting
means.

Exception No. 2: A single disconnecting means shall be
permitted for a group of coordinated controllers that
drive several parts of a single machine or piece of apparatus.
The disconnecting means shall be located in
sight from the controllers, and both the disconnecting
means and the controllers shall be located in sight from
the machine or apparatus.

Exception No. 3: The disconnecting means shall not be
required to be in sight from valve actuator motor (VAM)
assemblies containing the controller where such a location
introduces additional or increased hazards to persons or
property and conditions (a) and (b) are met.

(a) The valve actuator motor assembly is marked with
a warning label giving the location of the disconnecting
means.

(b) The provision for locking or adding a lock to the
disconnecting means shall be installed on or at the switch
or circuit breaker used as the disconnecting means and
shall remain in place with or without the lock installed.

That being the case it usually makes sense to place the motor starters in sight of the panel they are supplied from and run each circuit from there to the motors. 250' is not long considering you could use 12 or likely even 14 AWG for them.

Also from a maintenance and service perspective having the starters in some odd place just to make the installation easier stinks.

As far as MC or pipe ........ are you in business to make money or make art?

I would let the customer decide that, provide prices for both ways and let them decide if it is 'cheezy' or not.

 

[Besoeker]

He is, like me, an electrician first and a student of good writing much further on down the line.
Are you going to OK?

Well, the each and the one seem contradictory to me, literary skills notwithstanding............
We need the biker back....

On a nearly completely unrelated topic, television cooking shows have become rather popular here.
One such is called "The Hairy Bikers".
To look at they are archetypal Hell's Angels. But magic in the kitchen (where they might use electrical appliances..........had to get that in).

 

[Fulthrotl]

I know I am not on your Christmas card list but none the less I will toss this out.

Are you ready to do all that?

Here is my thought and it is radical.

Purchase five correctly sized enclosed magnetic motor starters a piece of wireway and put them together. Don't forget these are motor controllers and require a disconnecting means in sight of them.



That being the case it usually makes sense to place the motor starters in sight of the panel they are supplied from and run each circuit from there to the motors. 250' is not long considering you could use 12 or likely even 14 AWG for them.

Also from a maintenance and service perspective having the starters in some odd place just to make the installation easier stinks.

As far as MC or pipe ........ are you in business to make money or make art?

I would let the customer decide that, provide prices for both ways and let them decide if it is 'cheezy' or not.

"This thread has more than 10 replies. Click here to review the whole thread."

geeze... i can feel the lurve from here.....

i'm not ready to do "all that". it was about all i could do to wade thru the replies... :dunce:
i was trying to figure a way not to have to run 1,000' of 1/2" emt for five little motors.

your thought about 5 starters in individual enclosures was my first choice.
and the one i'd bid with, before i got busy trying to be creative
and painting myself into a corner. thank you for taking the time to respond.

each fan draws 4.8 amps... so even allowing for derating for multiple wires
in the conduit, #12 will still be ample, and the voltage drop on 480 will be
1.36% with #12 wire, so that isn't a problem, and the fugly truth is, doing
it your way will need *far less* pipe and wire than doing it my way.

the bestest way to do it would be to drop j boxes with 1/2" emt down thru
the sleeves on the fans, and connect it with 1" emt, and T condulets. put a
pull string in the pipe, and start at the end, and work my way backwards,
pulling a set for each fan. pull 10' out of the t, and shove it up to the roof.
put the cover on the t. move on.

add another pair of wires for the T stat, and put a t and run down a column
wherever the customer wants the t stat. use a 110 volt t stat, and thhn wire
for the t stat leads.

so, i've got one 1" emt run feeding five motors, five motor starters in individual
cans, one 1" emt going to the switchgear with some #8's in it to feed the starters,
a T stat on a column with a pair of wires going to it. the dots are connected, make
up the stuff, and i'm done.

the area the job is at..... it's bell gardens..... for those of you who know LA, it's
not the best area to work in.... but... it's better than compton... :happyyes:
at least i don't have to bring a helper to provide covering fire while i go to the
van for material...