plan review wire sizing and cord drops

[Krusscher]

I was handed off a project that started before I got to the college and they just got an approval on the plan review that I am seeing for the first time. I am assuming that they can get away with running #10 from a 35A breaker because it is feeding motor circuits? I would like to feed these with cord drops from the ceiling that only like 15/20ft and want to make sure what I am think is ok. Can I use strain reliefs from a 4 square to a twist lock recept with a strain relief on it? would I need to add strain relief to the whip from the machine? Does my Recept have to be sized for the breaker or can I size it for the actual load like they did with the wire? if anyone has any suggestions on the best way to do it/products I'm all ears.

 

[Little Bill]

I don't think you can use 4 sq boxes unless they have hubs.

(H) Pendant Boxes. An enclosure supported by a pendant
shall comply with 314.23(H)(1) or (H)(2).
(1) Flexible Cord. A box shall be supported from a multiconductor
cord or cable in an approved manner that protects the
conductors against strain, such as a strain-relief connector
threaded into a box with a hub.

 

[EricHL]

I don't think you can use 4 sq boxes unless they have hubs.

I appreciate you sharing this code. I was not aware of it or had forgotten. Recently I had a customer ask me to change from 4 sq to bell boxes for pendants but his reason was more durability than the hub. I interpreted the OP as asking if he could terminate the cord at the top in a 4 Sq box with strain relief and use cord cap receptacles with strain relief at the pendant end.


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[Krusscher]

I appreciate you sharing this code. I was not aware of it or had forgotten. Recently I had a customer ask me to change from 4 sq to bell boxes for pendants but his reason was more durability than the hub. I interpreted the OP as asking if he could terminate the cord at the top in a 4 Sq box with strain relief and use cord cap receptacles with strain relief at the pendant end.


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correct, I am putting a kellems grip after the 4 square in the ceiling to support it. I know I have seen cord cap recepts on the end of drops I just can't find anything that says it is or isn't ok in the code book.

 

[Krusscher]

Also they have a 20 amp breaker feeding this mill but there is no over current protection on the mill. It's intermediate duty so i believe it can be protected with the breaker but I don't think it can be that. According to 430.33 it looks to me like it would unfortunately need a 14.5 amp breaker unless i am missing something I would have to put a 10a in, would that hold? the other option I could do is put a disconnect with fuses.

 

[augie47]

You are correct, 430.33 allows you to use the branch circuit device to provide OL protection on this motor.
IMO, a 2HP motor would (Table 430.250) using 430.52 (next size up) would be protected by the 20 amp breaker.

 

[Krusscher]

You are correct, 430.33 allows you to use the branch circuit device to provide OL protection on this motor.
IMO, a 2HP motor would (Table 430.250) using 430.52 (next size up) would be protected by the 20 amp breaker.

ahh yes, I haven't had my coffee yet this morning and seem to have got ahead of my self and calculated using FLA and missed the exception in 430.52. Thanks! Do you have any input on the power drops for these?

 

[augie47]

I see no problem with using a cord with strain relief at the origon and a box with hub OR cord connector on the end.
Very common installation here.

 

[Krusscher]

Can someone site the code that allows the feeder conductors to be smaller then the SC/GF breaker feeding the motor controller? I thought I saw it yesterday but can't seem to find it today.

 

[augie47]

240.4. In your case 240.4(G)

 

[Krusscher]

maybe I am imagining it because I just can't find it in 430.

 

[augie47]

I don't think there's explicit wording in 430. Art 240 requires a conductor to be protected at it's ampacity WITH AN EXCEPTION for 240.4(G) which includes motor conductors and 430 Part II provides for conductor sizing whereas Part IV covers GFSC protection and applying those two parts allows you to comply with the 240.4(G) exception.

 

[Krusscher]

I don't think there's explicit wording in 430. Art 240 requires a conductor to be protected at it's ampacity WITH AN EXCEPTION for 240.4(G) which includes motor conductors and 430 Part II provides for conductor sizing whereas Part IV covers GFSC protection and applying those two parts allows you to comply with the 240.4(G) exception.

Ahh ok, thanks for that explanation, I was going crazy trying to find where it spelled it out that you can do it.

 

[Todd0x1]

So I have this right, you have a cord drop hanging from the ceiling with a female twistlock connector on it, and a cord coming from the machine with a male twistlock plug on it which is plugged into the cord drop? I HIGHLY suggest swapping those twistlocks for IEC 60309 series pin and sleeve connectors. I have been implementing them wherever I can with great success. Price wise they're only a few bucks more than a hubbell HBL series twistlock so money isn't a big deal.

 

[Krusscher]

So I have this right, you have a cord drop hanging from the ceiling with a female twistlock connector on it, and a cord coming from the machine with a male twistlock plug on it which is plugged into the cord drop? I HIGHLY suggest swapping those twistlocks for IEC 60309 series pin and sleeve connectors. I have been implementing them wherever I can with great success. Price wise they're only a few bucks more than a hubbell HBL series twistlock so money isn't a big deal.

That is how I was thinking. there are a few pieces of equipment hooked up now with a piece of EMT 90 down with FMC going to the equipment unsupported, which I believe is allowed up to 3 feet but I think they may have got liberal with it, not sure how it passed but it must have. The way I've done it in the past is dropping rigid from the ceiling to an anchored post and putting an disconnect/outlet on it which I might consider instead just for looks and safety.

 

[Todd0x1]

Nice Haas.

I'd land the conduit in a box at the ceiling, drop Bus Drop Cable down from there into a pin and sleeve connector. Normal cable grip into the box, then independently support the drop with a Bus Drop Cable Clamp.

I've done a few of these where they wanted a lockable disconnect external to the machine so we would build a strut frame next to the machine with conduit from the ceiling into a disconnect switch, then jump from that to the machine with liquidtite. We'd also bring the air line down the strut frame, add ball valve, moisture trap, and point of use filter/regulator. I doubt your guys would want to lose the floor space to the strut frame.

Take a look in a mcdonalds kitchen, many(most?) of them have the equipment fed from overhead with bus drop cable and pin+sleeve connectors.

 

[Little Bill]

So I have this right, you have a cord drop hanging from the ceiling with a female twistlock connector on it, and a cord coming from the machine with a male twistlock plug on it which is plugged into the cord drop? I HIGHLY suggest swapping those twistlocks for IEC 60309 series pin and sleeve connectors. I have been implementing them wherever I can with great success. Price wise they're only a few bucks more than a hubbell HBL series twistlock so money isn't a big deal.

Curious, why the pin & sleeve instead of twist lock?

 

[Todd0x1]

Curious, why the pin & sleeve instead of twist lock?

It's just a better connector, and the good twistlocks have gotten so expensive you can get pin and sleeve for not much more $.

 

[Krusscher]

Nice Haas.

I'd land the conduit in a box at the ceiling, drop Bus Drop Cable down from there into a pin and sleeve connector. Normal cable grip into the box, then independently support the drop with a Bus Drop Cable Clamp.

I've done a few of these where they wanted a lockable disconnect external to the machine so we would build a strut frame next to the machine with conduit from the ceiling into a disconnect switch, then jump from that to the machine with liquidtite. We'd also bring the air line down the strut frame, add ball valve, moisture trap, and point of use filter/regulator. I doubt your guys would want to lose the floor space to the strut frame.

Take a look in a mcdonalds kitchen, many(most?) of them have the equipment fed from overhead with bus drop cable and pin+sleeve connectors.

Do the cord caps need any sort of extra strain relief added to them?

 

[Krusscher]

I've also just added a rack off the picking bolt holes on the top of the panel to support a conduit going into the top of a panel. But i believe if you hard pipe it in the machine has to be anchored and the ones I'm connecting are not.