Cable Limiters as OCP? Looks fishy to me.

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lile001

lile001

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Midwest
This can't be legal, but I am not sure how yet.

I have a large service entrance, fed with 10 sets of 750MCM aluminum cable. Each 750MCM cable ends in a Buss KFM 750MCM Cable limiter.

The switchgear consists of six bolted pressure switches. There are no main fuses, other than those cable limiters.

Loads downstream include MLO panels, automatic transfer switches, and other items without any overcurrent protection.

Am I correct in my belief that these 750 MCM Cable limiters are inadequate as the only OCP in the service entrance?

I understand the "six throws of the hand" rule, but was it really meant to indicate six unfused switches?
 
Cable limiters are typically used as a supplementary product to keep a system running if one cable goes bad. I don't see how using them as described would allow you eliminate overcurrent protection at the service. Here's some info if anyone is interested:

http://www.bussmann.com/pdf/1042.pdf
 
benaround said:
Lawrence,

Without knowing more, what you discribed is code compliant 230.70 & 230.71
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So what provides overcurrent protection for the downstream feeders?
 
After the 6 switches, the feeders require overcurrent protection Article 240.
Without OCPD, what is the withstand rating of the switches? Are they high enough for your available fault current? Usually not without fuses or other actual OCPD.
 
Trevor,

My guess is that from the location described by OP'er, that everything

downstream is run 'outside' and until they go 'into' a structure or just outside

will the OCP be required. Does that sound right to you?
 
id never heard of cable limiters before, so i have a dumb question: if for example, i had a service with 8 sets of parallel feeders with a cable limiter on each conductor, how would i ever know if i lost one or more cables until its too late?
 
wireguru,

It is my understanding that the c.l.'s would only be reacting after a 'short

circuit' on the system has already occured, their function would be to save

the conductors from arcing, burning, melting,etc., but that 'short' would be

your first clue that investigating 'upstream' in this case would be needed.

JMO
 
lile001 said:
I understand the "six throws of the hand" rule, but was it really meant to indicate six unfused switches?
Click to expand...
I guess the first thing that pops in my mind is to ask, are you sure that they're not fused under a panel right above each boltswitch?
 
benaround said:
Trevor,

My guess is that from the location described by OP'er, that everything

downstream is run 'outside' and until they go 'into' a structure or just outside

will the OCP be required. Does that sound right to you?
Click to expand...


You maybe right but that wouldn't be my guess given the information in the OP:

The switchgear consists of six bolted pressure switches. There are no main fuses, other than those cable limiters.
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I don't envisage this to be on the outside of the building.
 
Lawrence Lile, P.E. ,
Cable limiters are only for the protection of the individual wires and can not be used as the sole means of Overcurrent Protection. As Roger stated you will need to introduce a form of Overcurrent Protection, either a fuse or breaker.
I see Unility companies and Colleges using these alot.
Rob said it best
Cable limiters are typically used as a supplementary product to keep a system running if one cable goes bad. I don't see how using them as described would allow you eliminate overcurrent protection at the service. Here's some info if anyone is interested
Click to expand...
Just my $.03, used to be $.02, but corrected for inflation.
 
Don't you just hate it when someone posts a question and then never comes

back to clarify the situation. It leaves the question unanswered and little

benifit to the members.
 
benaround said:
Don't you just hate it when someone posts a question and then never comes

back to clarify the situation. It leaves the question unanswered and little

benifit to the members.
Click to expand...


Yes, you can add me to the list of haters.:mad:
 
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