Power Distribution Options - 150 Amps

tspisak · Mar 10, 2015

Does anyone know of a clever way to distribute 480 vac, three phase voltage for applications over 100 amps? I have a project where the customer wants to have a single point power disconnect of 150 amps for multiple cells. The power gets split out to power for transformer, automation, conveyor motors, and the PLC panel.

The wire size is too large coming out of the disconnect to fit in to the 30 amps fuse holders. May just have to put in an intermediate fuse allow the use of smaller gauge wire and just up-size the enclosure.

Gomez_ · Mar 10, 2015

Normally we come out of our main disconnect into something like this:
http://www.mscdirect.com/product/details/84720556

Then go into whatever type of branch protection we are using.

You'll have to find the correct unit for the wire sizes you need.

nonuke · Mar 10, 2015

This is a brand-new power distributor that effectively reduces your wiring complexity in the field with M12 power distributor connectors.

Drawback:
Only up to 32 A and 10A for each M12 plug.

http://catalog.weidmueller.com/proc...6DC7BDE?productId=([1542580000])&page=Product

jseavers · Mar 10, 2015

I like these Bussman Ones:

tspisak · Mar 10, 2015

We use power distribution terminal blocks too (I prefer the IEC type but they are expensive). The problem is the wire size (#1 AWG) is too big to fit into a 30 amp fuse holder.

Gomez_ · Mar 10, 2015

tspisak said:
We use power distribution terminal blocks too (I prefer the IEC type but they are expensive). The problem is the wire size (#1 AWG) is too big to fit into a 30 amp fuse holder.

If you use the distribution blocks then why are you running a ~200 amp wire into a 30 amp fuse?

jstolaruk · Mar 10, 2015

Unless he's trying to get away with not using PDPs, hoping to jump from the disconnect-to-holder-then-to-holder, etc. And that would not be good.

"May just have to put in an intermediate fuse allow the use of smaller gauge wire and just up-size the enclosure. "

Best fire the panel designer, spring for the PDPs, and make sure its in the quote for the next panel. Multiple wires coming out of the intermediate fuse holders will look poor to anyone used to dealing with power distribution. My customer's would reject it.

tspisak · Mar 10, 2015

The order of the devices would be:
200 amp disconnect with 150 amps fuses
Power Distribution Terminal Block
(6) 30 amp - 3 phase fuse holders

The wire to handle to 150 amps into and out of the power distribution block is too big to fit into a 30 amp fuse holder.

Shouldn't the the wire be sized to match the 150 amps fuse that is protecting the wire downstream of the disconnect until the next fuse?

Gomez_ · Mar 10, 2015

tspisak said:
Shouldn't the the wire be sized to match the 150 amps fuse that is protecting the wire downstream of the disconnect until the next fuse?

The wire from the distribution to the 30A fuse should be sized for that.

jstolaruk · Mar 10, 2015

The power distribution block should a single connection to the inboard side and the outboard side should have multiple 30 amp wire connections. Sounds like you've got the wrong model there?

TWS · Mar 10, 2015

Per NEC 240.21 (B) you can use 1/0 AWG (150A)wire from your main disconnect to your power distribution blocks. then use 10AWG (30A) wire to your 30A fuse holders. The total length can not exceed 10 feet. The tap conductors can not extend beyond the the panel that your main disconnect is in.

rkukl · Mar 10, 2015

Are all of the fuse holders in the same enclosure?

TWS · Mar 10, 2015

TWS · Mar 10, 2015

Per code they have to be

tspisak · Mar 10, 2015

TWS - Thanks! That is what I needed. I thought that you had to size ALL of the conductors for the fuse above the PDTB in case of a direct short to ground.

All of my power distribution is in the same cabinet so I am good to go.

Power Distribution Options - 150 Amps

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