How to reduce wire size

[LMAO]

I was just wondering if there is a way (adapter/reducer) to reduce a wire size so it can fit in a distribution block (power terminal block) that otherwise cannot fit that wire size? For example, I need to terminate 300MCM wire into a terminal block that can accept up to 1/O wire. Maybe something like a big ferrule except with much smaller end that can fit in the terminal block.
Sorry if a dumb question.

 

[ActionDave]

There are pin adapters made or you can use a polaris connector to spliced down to a smaller wire.

 

[Julius Right]

See-for instance:
http://ecat.burndy.com/Comergent//burndy/documentation/section k-underground.pdf
page K-67 Type YRB31U25TW
There are other possibilities also.

 

[infinity]

I'm not sure that a pin style adapter would allow you to reduce from a 300 kcmil all the way down to a #1/0 (there has to be a practical limit before heating becomes a factor) . These from Ilsco only go down to a #4/0 from 300 kcmil.

https://commerce.ilsco.com/e2wShoppingCatalog.aspx?parentId=3100012972&parentLink=:3100012972

 

[GoldDigger]

I'm not sure that a pin style adapter would allow you to reduce from a 300 kcmil all the way down to a #1/0 (there has to be a practical limit before heating becomes a factor) . These from Ilsco only go down to a #4/0 from 300 kcmil.

You could get away with a higher ratio transition if the larger diameter wire was used only for voltage drop purposes, not for ampacity.

 

[infinity]

You could get away with a higher ratio transition if the larger diameter wire was used only for voltage drop purposes, not for ampacity.

I agree, I would guess that the manufacturers have this all figured out.

 

[mjmike]

FYI, I have ran into problems where a panelboard manufacturer would not stand behind the use of the pins because of the limited bend radius of the conductors; add the pins and not enough room for the bend radius.

 

[petersonra]

FYI, I have ran into problems where a panelboard manufacturer would not stand behind the use of the pins because of the limited bend radius of the conductors; add the pins and not enough room for the bend radius.

get a couple crimp on lugs and bolt them together and put some heat shrink over the splice.

 

[Smart $]

FYI, I have ran into problems where a panelboard manufacturer would not stand behind the use of the pins because of the limited bend radius of the conductors; add the pins and not enough room for the bend radius.

Technically, the manufacturer does not have to stand behind the use of pin terminals. The manufacturer has to provide the minimum required bending space. That is where their burden ends.

Even under the NEC, there is only a minimum bend space requirement. There is no minimum bend radius for the conductors.

 

[Smart $]

get a couple crimp on lugs and bolt them together and put some heat shrink over the splice.

I'd like to see a ring-crimp sleeve that permitted trimming off strands on the terminus side. It is essentially no different than the wire type reducer like Rob posted earlier.

 

[LMAO]

Thank you all. Very useful info.

 

[Carultch]

You could get away with a higher ratio transition if the larger diameter wire was used only for voltage drop purposes, not for ampacity.

If 110.14(C) terminal ampacity is an issue at the largest size that can practically be terminated in the piece of equipment in question, then the product should've never passed UL standards in the first place.

One possible explanation if you do come across a situation that might seem insufficient, is that the equipment manufacturer expected you to use a different quantity of sets in parallel, than you intend to use. For instance an 800A breaker that is built for maximum 500 kcmil. If you need to get the full 800A, you can't use 2x500's, and you can't directly connect 2x600's. You are likely expected to use 3 sets in parallel. You'd therefore need a 5-terminal tap block, capable of up to 600 kcmil, to rearrange the paralleling from 3x300 to 2x600.

 

[electrofelon]

terminal blocks and splicers are never provided with a current rating, so how do we know when or how much we can reduce?

 

[petersonra]

terminal blocks and splicers are never provided with a current rating, so how do we know when or how much we can reduce?

every terminal block I have used comes with a current rating.

 

[electrofelon]

every terminal block I have used comes with a current rating.

Oh really? OK, I guess I rarely use terminal blocks. I guess I am thinking more of polaris type connectors, and SS butt splices.....

 

[petersonra]

Oh really? OK, I guess I rarely use terminal blocks. I guess I am thinking more of polaris type connectors, and SS butt splices.....

those are not terminal blocks.

my understanding is that the Ul stds for connectors like the polaris blocks require that they be able to handle the largest amount of current the conductors can bring in based on the NEC. I think that is why they get to be so big sometimes.

 

[Besoeker]

You could get away with a higher ratio transition if the larger diameter wire was used only for voltage drop purposes, not for ampacity.

Totally agree. As I see it, the correct solution would be to change the termination block.

 

[Carultch]

those are not terminal blocks.

my understanding is that the Ul stds for connectors like the polaris blocks require that they be able to handle the largest amount of current the conductors can bring in based on the NEC. I think that is why they get to be so big sometimes.

So suppose you have one that is rated for 6x 3/0 conductors. In terminals 1 thru 3, you connect the inbound wires. In terminals 4-6, you connect the outbound wires. All 3/0. This means that at the extreme corss section, it would have to be rated for 675A, to handle the maximum current that 3 sets of 3/0 could handle.

Is this correct? Are these types of connectors rated for the maximum possible current that could be present, no matter how you arrange inbound & outbound wires? I take it that it is designed assuming that half of the terminals are fed with the 90C rating of the maximum possible conductor one can connect.

Ideally you would arrange the wires to minimize the current on the connector, so that it cancels rather than accumulates.

 

[Smart $]

... Ideally you would arrange the wires to minimize the current on the connector, so that it cancels rather than accumulates.

Been a while since I read instructions but I believe it states something to the effect of staggering line and load conductors for this purpose.

 

[JFletcher]

So suppose you have one that is rated for 6x 3/0 conductors. In terminals 1 thru 3, you connect the inbound wires. In terminals 4-6, you connect the outbound wires. All 3/0. This means that at the extreme corss section, it would have to be rated for 675A, to handle the maximum current that 3 sets of 3/0 could handle.

Is this correct? Are these types of connectors rated for the maximum possible current that could be present, no matter how you arrange inbound & outbound wires? I take it that it is designed assuming that half of the terminals are fed with the 90C rating of the maximum possible conductor one can connect.

Ideally you would arrange the wires to minimize the current on the connector, so that it cancels rather than accumulates.

I was looking at some connectors the other day and arrangement of the i/o did matter. No idea their amperage rating, tho Polaris connectors and the like look beefy enough to take any current the connected wires would... iow, if there were some extreme fault and the OCPD didnt trip/wasn't there, I doubt the connector would be the failure point.