10hp 230v single phase compressor wiring help

[wyliesdiesels]

pressure control switches are generally insulated with Teflon tape. This does not make for a good ground. I would like to see a pressure switch which is rated for more than .5 A without a ground terminal. The fusing only helps on both the circuit side and the safety side. You might consider this redundant, some manufacturers do as well (and they skate) under the NEC requirements for bonding. but it doesn't make it right.

Maybe the OP can show picture of the pressure control valve circuitry for more clarification?

Right but the starter enclosure is grounded(should be). SO why does it matter that the switch isnt bonded via the tank?

What does that have to do with a hot wire shorting to the grounded enclosure?

Why would the presence of a ground terminal effect the current capacity of a pressure switch?

If its not required by NEC, then why do you say its not right?

You really lost me here.

 

[Matt Matt]

Right but the starter enclosure is grounded(should be). SO why does it matter that the switch isnt bonded via the tank?

What does that have to do with a hot wire shorting to the grounded enclosure?

Why would the presence of a ground terminal effect the current capacity of a pressure switch?

If its not required by NEC, then why do you say its not right?

You really lost me here.

Let's be patient and see if the switch is required to have grounding.

 

[Matt Matt]

Right but the starter enclosure is grounded(should be). SO why does it matter that the switch isnt bonded via the tank?

What does that have to do with a hot wire shorting to the grounded enclosure?

Why would the presence of a ground terminal effect the current capacity of a pressure switch?

If its not required by NEC, then why do you say its not right?

You really lost me here.

I think what you're saying is the NEC writes the rules on manufacturing. This is not true. The NEC governs the rules, but manufacturing supersedes with when they have received a stamp from UL. Once a old ul has been achieved, it does not mean that New ul would (In the same situation). Under the NEC as soon as original manufacturing wiring has been modified or tampered with (outside of a certified manufacturing facility) A new inspection is required. A new certification sticker is required.

I personally do not possess or would plead to possess the ability to certify modified equipment. This is what my technologist does. I am only giving or trying to give some helpful information. You get what you paid for.

 

[wyliesdiesels]

I think what you're saying is the NEC writes the rules on manufacturing. This is not true. The NEC governs the rules, but manufacturing supersedes with when they have received a stamp from UL. Once a old ul has been achieved, it does not mean that New ul would (In the same situation). Under the NEC as soon as original manufacturing wiring has been modified or tampered with (outside of a certified manufacturing facility) A new inspection is required. A new certification sticker is required.

No Im not saying that. I was responding to your comment on how "some manu. consider it redundant to fuse control wiring under NEC bonding but it doesnt make it right."

If the unit is U/L tested and listed WITHOUT control fusing, then how does it make it "not right" in your opinion? That is what I was asking...

I personally do not possess or would plead to possess the ability to certify modified equipment. This is what my technologist does. I am only giving or trying to give some helpful information. You get what you paid for.

Right.

And the overload in the OPs case was factory wired so why are we suggesting he change how it is wired by the manufacturer? Which as you point out is modifying certified/listed equipment....

Why not just put the pressure switch and oil switch on L1/A1, add some fuses if we must, and call it good?

Overload relay block is already wired. Why change it around? What is the point is what I am asking... Doing more work when its not needed.

Dont take this the wrong way. Im asking questions to understand your thought process, idea behind your suggestions. Not saying you are wrong...

 

[Matt Matt]

I think the main point,you were dogging on my wiring schematic was the fact that I wanted to implement external wiring being fused properly??? The NEC now requires this. A UL inspector requires this too, or sufficient grounding.

But, i'm still waiting for the pressure control circuit picture.

 

[mm08822]

And the control ckt I drew and posted in post 34 shows the factory wiring intact and according to standard convention - o/l's after the coil. Just needs fuses since the control ckt leaves the starter enclosure.

 

[wyliesdiesels]

I think the main point,you were dogging on my wiring schematic was the fact that I wanted to implement external wiring being fused properly??? The NEC now requires this. A UL inspector requires this too, or sufficient grounding.

But, i'm still waiting for the pressure control circuit picture.

Actually the main thing i was pointing out was how the overload relay was already wired. why mess with that.

If fuses are required then i stand corrected.

Ive apparently seen many violations of 430.72...

 

[Matt Matt]

And the control ckt I drew and posted in post 34 shows the factory wiring intact and according to standard convention - o/l's after the coil. Just needs fuses since the control ckt leaves the starter enclosure.

I tried to say this toooo...

 

[mm08822]

And another point....aside from ocp of the control circuit conductors. If you did not have ocp in the control ckt, the external control devices remote from the starter would have to have the same size egc as determined by the power ckt ocp!
So in this case, the fmc would not be adequate. you'd be running #10 greens.

 

[matt_i]

Just curious why would you change the factory overload control wiring by adding in the pressure switch?

Why not leave it alone and just wire pressure switch and oil switch to L1/A1 side?

Unless Im misinterpreting your diagram..

Its just a functional diagram. The components can go in any order and will work exactly the same, just wire the control components (to include the NC oil=low contact that I don't show) in series is the only requirement.

I thought a little about the fuses. My first thought was "only one" would be required in the circuit. However being a vibratory piece of equipment, the control wiring could potentially rub thru to ground (this being a fail mode of the control circuit). And so there is a current path from L1->gnd and also L2->gnd. Its my personal opinion that asking a #14awg to carry enough fault current to trip a 60+ amp breaker might be stretching it. I think #12 awg would probably do it without a problem. So depending on the wire size used, definitely with thinner stuff the two fuses would be more useful. I would think something like a 2A glass fuse would be plenty. That should give around ~500VA capacity for actually running the control circuit as normally intended.

 

[mm08822]

Its just a functional diagram. The components can go in any order and will work exactly the same, just wire the control components (to include the NC oil=low contact that I don't show) in series is the only requirement.

I thought a little about the fuses. My first thought was "only one" would be required in the circuit. However being a vibratory piece of equipment, the control wiring could potentially rub thru to ground (this being a fail mode of the control circuit). And so there is a current path from L1->gnd and also L2->gnd. Its my personal opinion that asking a #14awg to carry enough fault current to trip a 60+ amp breaker might be stretching it. I think #12 awg would probably do it without a problem. So depending on the wire size used, definitely with thinner stuff the two fuses would be more useful. I would think something like a 2A glass fuse would be plenty. That should give around ~500VA capacity for actually running the control circuit as normally intended.

Only the o/l's after the coil to follow standard convention. Anything else in any order before the coil.

Two fuses would be required in this control ckt as either conductor can go to grd.

#12's would work without fusing but only for a 60A ocp. If the OP's inrush trips the 60, then he has to go higher and 10's would cover it up to a 90A cb.
Know many control devices handling #10's??? Fuse it and be done with it.

 

[thinktwicez71]

pressure control switches are generally insulated with Teflon tape. This does not make for a good ground. I would like to see a pressure switch which is rated for more than .5 A without a ground terminal. The fusing only helps on both the circuit side and the safety side. You might consider this redundant, some manufacturers do as well (and they skate) under the NEC requirements for bonding.but it doesn't make it right.

Maybe the OP can show picture of the pressure control valve circuitry for more clarification?

Is this what you were looking for ?

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[thinktwicez71]

Got the jumper wire installed

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[Matt Matt]

Yeah, that was what I was looking for. Is this a ground screw?

And generally Teflon tape or pipe dope is considered an insulator. So a ground wire should be ran with the power leads.

 

[thinktwicez71]

Edit.....I see what your pointing at now . I'll go back out and check if that's a ground screw , sorry


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[thinktwicez71]

For the low oil cutoff 2 wires and the pressure switch 2 wires tell me if this is correct .

One wire from the low oil switch goes to L1
One wire from pressure switch goes to A1
The second wire from both get wire butted together ?


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[mm08822]

For the low oil cutoff 2 wires and the pressure switch 2 wires tell me if this is correct .

One wire from the low oil switch goes to L1
One wire from pressure switch goes to A1
The second wire from both get wire butted together ?


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see pics in reply 34.

 

[thinktwicez71]

Is there a toggle switch I could add to this for my on off switch ? Is there one rated for this application?

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[thinktwicez71]

I got my answer in #37 from wylie ,( for the pressure switch wires) I'm horrible understanding drawings like that

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[wyliesdiesels]

Is there a toggle switch I could add to this for my on off switch ? Is there one rated for this application?

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One thing i dont recall if it was brought up is how far away is the panel from the compressor?

And is it within sight of the compressor?

As for the switch, theres a number of ways to go about it.

You could use an A/C pullout disconnect(you will need one if further than 50' away and not within sight of panel).

You could tie it into a dedicated light switch by a man door (make sure to use fuses on the control wires) or could put a switch on the starter housing.

 

[thinktwicez71]

One thing i dont recall if it was brought up is how far away is the panel from the compressor?

And is it within sight of the compressor?

As for the switch, theres a number of ways to go about it.

You could use an A/C pullout disconnect(you will need one if further than 50' away and not within sight of panel).

You could tie it into a dedicated light switch by a man door (make sure to use fuses on the control wires) or could put a switch on the starter housing.

Compressor is within 15 feet of panel box

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[mm08822]

[/ATTACH]

For the low oil cutoff 2 wires and the pressure switch 2 wires tell me if this is correct .

One wire from the low oil switch goes to L1 yes
One wire from pressure switch goes to A1 yes
The second wire from both get wire butted together ? yes


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Is there a toggle switch I could add to this for my on off switch ? yes Is there one rated for this application? 15A 240vac toggle switch

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See attached sketch. It would be better to put the toggle switch first. Just interchange the oil switch and toggle switch in my sketch.

 

[thinktwicez71]

Much appreciated , I understand that perfectly


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[matt_i]

If you do a traditional "wall switch" mounted in an actual wall it would be wise to mark or label the fact that you have 240vac present because most people would not be expecting that and even if I did that myself I would probably forget the details in about 2 years

 

[thinktwicez71]

If you do a traditional "wall switch" mounted in an actual wall it would be wise to mark or label the fact that you have 240vac present because most people would not be expecting that and even if I did that myself I would probably forget the details in about 2 years

Any switch I put on will be mounted to this compressor

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[wyliesdiesels]

If you do a traditional "wall switch" mounted in an actual wall it would be wise to mark or label the fact that you have 240vac present because most people would not be expecting that and even if I did that myself I would probably forget the details in about 2 years

The switch should only have 120v present since its switching only one side of the coil.

Its no different than a light swicth

 

[thinktwicez71]

The switch should only have 120v present since its switching only one side of the coil.

Its no different than a light swicth

Will a 15a 125v toggle switch work? That's how they turned the old motor starter on and off for 3 phase , I could just reuse this one .

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[mm08822]

You could b/c it is rated for 250vac. That is the voltage it is making/breaking.

 

[thinktwicez71]

Wouldnt it be 120v seeing as im only breaking one leg of the coil ?

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[mm08822]

Wouldnt it be 120v seeing as im only breaking one leg of the coil ?

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No. its a 240v coil fed from 240v. Each leg to grd is 120v, but you are opening a circuit between 2 hots. Therefor 240v.

Wire it up and with the oil switch closed and ps closed, measure the voltage across the open switch terminals.

 

[Matt Matt]

The switch should only have 120v present since its switching only one side of the coil.

Its no different than a light swicth

That would only be true in England but they are 240 to ground/common . But North America, we have +120 V -120 V through the zero line for single phase.

 

[Matt Matt]

Will a 15a 125v toggle switch work? That's how they turned the old motor starter on and off for 3 phase , I could just reuse this one .

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The switch you have is a double pole double throw. Since commonly you are suppose to stop all hot power during switching, this switch can do that. This which is similar to a double breaker (240 V breaker). On the back you have the centre connection. This is also known as a common in this type of switch. The connections on the on the side would go from common to on. There is also a common to off switch. You could send power to something when it's in it's off position.

 

[Matt Matt]

Wouldnt it be 120v seeing as im only breaking one leg of the coil ?

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Again no. You are switching a 240 V circuit. The coil is 240 V and you have 120 V going to both sides of the coil . It does not matter where you measure the voltage in the circuit, you will always be switching 240 V.

Now if you wanted to get advanced and you wanted to put a Edison three wire circuit in this would be true. We run an Edison three wire circuit in our homes (to an extent through the main panel). To get 120 V on a 240 V circuit you would need to lightbulbs or coils run in series. But without the common Centre tap, both devices would need to have the same wattage. The centre tap allows for the offset of wattage to be diverted into the common. To take this a little step further, if you brought along the neutral like provided in the stove plug, you could have multiple 120 V circuit's run from either leg. When the wattage becomes 100% balanced from both +120v &-120v The common would not be carrying any voltage. Even though common is known as a voltage carrying, it would not be returning anything.

 

[wyliesdiesels]

3hrs of sleep is NOT good for the brain.

Yeah duh the coil would be passing the other leg through to the switch. So yes 240v would be available at the terminals of the switch.

I think Ill go to bed early tonight....

 

[thinktwicez71]

For the motor connections itself I wanna make sure this is right . I have 4 motor leads inside the box. They are all labeled with a number like on the chart in the picture . So to make sure I understand this.... I got split bolts electrical tape and rubber tape from the motor shop , but failed to ask him how to wire it while I was there .

T1 FROM STARTER plus 1 and 5
T3 FROM STARTER plus 4 and 8 ?

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[wyliesdiesels]

For the motor connections itself I wanna make sure this is right . I have 4 motor leads inside the box. They are all labeled with a number like on the chart in the picture . So to make sure I understand this.... I got split bolts electrical tape and rubber tape from the motor of but failed to ask him how to wire it while I was there .

T1 FROM STARTER plus 1 and 5
T3 FROM STARTER plus 4 and 8

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yes if you want it to spin clock wise.

It all depends on the direction the pump needs to spin.

Verify the proper direction on your pump, then hook up motor leads accordingly.

 

[thinktwicez71]

Right , the clock wise rotation looking at the end opposite the shaft extension is based on the big flywheel on the pump has a arrow on it .


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[thinktwicez71]

Ok line wires are done I just gotta get a ring terminal for my ground wire in the motor box, or maybee a panel box add on ground lug for it . Pretty sure 6 guage thhn isn't gonna fit behind a usual hex head ground screw .

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[thinktwicez71]

How would you attach that 6 guage green thhn wire to that green ground screw ?

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[matt_i]

I would use this

http://www.homedepot.com/p/Steel-Ci...ed-to-14-Solid-Wire-2-Pack-L70-B2-5/100141680

Google "Home Depot Copper Mechanical Lug"