UL508A - Type E Disconnect at Motor

480V. 40HP to 50HP pumps. PLC control. 24DC.

Customer specified Fused Disconnects at each pump. We are opting to do Fused Disconnect (UL98) - Contactor - Overload at each. Through the door handle with lockout/tagout.

Can I also use a Type E Combo Disconnect - Contactor?
Id the Type E treated the same as a Fused Disconnect?
Looks like it will, but I want to be sure before proposing this option to customer. See attached PDF.

When I see the phrase "fused disconnect at each pump" I think of this kind of device ( https://www.mcmaster.com/#fusible-disconnect-switches/=16sn4de ) mounted in close proximity to the pump motor. It appears the Type E device is intended for mounting inside a panel, and it sounds like you are intending this to be a full motor starter. I'd check with the customer to make sure of what they want.

Normally, I do all in one Control Panel. 480V main, PLC, and full motor starters. Everything must be UL508A.
I don't want to put fused disconnects at the outputs of the starters. If I'm doing fused disconnects at pump, then I can do a full starter, and eliminate the 480V in the Control Panel. Just have them do a 480V drop to each motor. I'll do 24V control from Control Panel to Starter.

Everything is outdoor.

If your control panel is "within sight" of the motors and the handles for your Type E devices are on the outside and lockable, then it should be an acceptable option. But if their spec calling for a disconnect at the motor is because you are required to have a LO/TO point within sight, and your control panel is not, then I'd say you need another disconnect. Now would that need to be FUSED if the starter feeding it is fused or a Type E starter? No. Although having redundant OCPDs is not forbidden, it's a bad idea because you add potential confusion when it stops working; which OCPD cleared and where?

BUT...
I've never seen a UL Listed Type E starter like what you showed that is rated for 50HP, they typically stop at 20-40HP depending on the mfr. Some make larger versions (up to 60HP), but those are not Type E, they are only UL 508 listed for GROUP motor installations, meaning they require additional coordination with upstream protection devices, usually current limiting fuses, which for your purposes, kind of makes them pointless.

Side note: Every IEC based Type E starter I have ever seen is rated for use ONLY on 480Y277V systems. They CANNOT be used on 480V delta power sources. That's rare now, but worth noting.

the rules may have changed since I built controls, but this is my take on the code.

in the main control panel, you have your 480 volt contactors with overload
protection.

this overload protection protects the panel and wiring to the motor against
shorts, cut wires.

you then have to go to the motor.
NEC line of sight is defined as 50ft and you HAVE A DIRECT LINE OF SIGHT to the main control panel disconnect. No turning corners or placing objects later on in the line of sight, so I would put a disconnect with loto capabilities at the motor.

from the disconnect, you can go 6ft if my memory is correct using metallic sealtite.

regards,
james

Thank you, jraef. Local LO/TO is required "at pump".
I was considering LS MMS-100H. The PDF says Type E.
I hate fuses. They are expensive. If only one clears, then the motor is single-phased until another one clears. Aware of cost, the electrician only replaces the blown ones, leaving the last "margined" fuse to nuisance trip next week.

James, they want to put a box on the motor/pump frame. The sealtite is about 3 feet. Normally, I just use an unfused disconnect here with LO/TO.

3ft is ok.

you still need to protect the system from the main panel to the motor disconnect if a wire gets cut! please check nec 70, I think its section 430

if we do it the way the customer wants and a #4 (best guess) wire gets cut or shorts to ground, How much current do you think will be going through that wire to ground? what do you think the calories generated will be in regards to arc flash requirements?

With todays code, you not only have to design the panel and wiring, but you also have to take into account NEC70E - Arc Flash.

if you did it the customer's way, just a guess on my part, but I would say that a cat 4 suit will be required just to open the door of the enclosure. maybe a cat 6.
what if someone is in that panel when the wire gets cut, the arc flash can do major damage to them.
I just saw the result in a plant last month and osha was not happy.

Please look at NFPA79, NEC 70 and NEC70E for your requirements.
if the code says protect the wiring from the panel to the motor disconnect, end of discussion, you protect the wiring. Doesn't matter what the customer wants, you must build panels to the current electrical standards OR face the consequences later and you (the designer) will also be right there with your boss.

Others may disagree with me and that's fine. I am stating my experience of designing for 30+ years.

I apologize if this post offends anyone, Safety begins at the design stage, build stage, and every day operations. No one needs to go through what happened to that individual ! EVER !

regards,
james