City of LA Not Allowing Current Limitation Fuse Let-Through fues

[stuartdmc]

We've installed a 600 amp 120/240v 3 wire meter section with (6) meters and (6) 100 amp mains type "T" pull-out fusses feeding (6) different units in the city LA.

We had to update the plans and while during plan check the plan checker stated that LA City does not allow fuse let through and that we'll have to remove the meter section's main fuses and replace them with circuit breakers.

I need to try and find away to fight the city on this or to find an exception to the ruling. Does anyone know of this ruling and how to get around it?

FYI
In the (6) different units, the panel-boards are all different manufactures ones a cutler hammer ones a square D, etc. so to avoid changing out all panel-boards we installed fused mains.

Does anyone know of a slick fix?



Thanks.
Stuart

 

[Sierrasparky]

Was the project already approved with the fuse layout as you have indicated?
I would check to see if they have an ordinance in place.

Many years ago we had a project that was designed by an engineer and he made a mistake and used fuses in the plans eventhough we told him we were using breakers. The inspector refused to allow the breakers and we had to re-submit with a breaker single line to get approved.

 

[acrwc10]

I have never heard of a "no fuse" code. I would ask the city code section. Not saying they don't have such a code but sounds odd.

 

[hmspe]

I'd ask for a specific Code reference or a copy of the written policy. The only way this makes sense to me is if the reviewer is referring to current limitation during short circuit conditions -- the "up, over, and down" approach. The up, over, and down method for fuse/breaker systems went out of favor 15 or so years ago. Have you done fault current calculations? If the panels are reasonably new you should be able to series rate with the fuses, but if I was the reviewer I would expect to see calculations to justify the rating.

 

[rbalex]

Presumably he is citing the City's Electical Plan Check Corrections List, Section F.6. However, if you check the citations used to justify it, CEC 110.9&10 and LA City's Muncipal Code 93.0207, NONE of them nor the LA City Amendments say anything like that. I don't know who authored the Plan Check Crrections List, but it is full of preferential material that hasn't actually gone through the City, much less the California Building Commission's review. If you're willing to fight it, take it up the ladder with what I told you - even to the CBC, if necessary.

For 93.0207 "easy" reference:

SEC. 93.0207 INFORMATION REQUIRED ON PLANS OR SPECIFICATIONS.
The following information is required to be shown on plans, specifications and diagrams submitted for review by the Department: (Amended by Ord. No. 176,775, Eff. 8/1/05, Oper. 8/1/05.)
(a) A complete plan showing the layout of the proposed electric systems for each floor or area, including dimensions of all working spaces, a full scope of the project and a legend of all symbols used. (Amended by Ord. No. 172,593, Eff. 6/28/99, Oper. 7/1/99.)
(b) The type, location and capacity of all service equipment.
(c) The size and the length of all service raceways to the manhole, vault or pole of the serving agency or to the service head.
(d) The size of all raceways and the length of all feeder raceways.
(e) The dimensions of all pull or junction boxes larger than four inches trade size.
(f) The number, size, and type of all conductors to be installed in wiring enclosures.
(g) The location of every proposed outlet and switch in all parts of the building or structure including all fixed showcases, wall cases, and similar wiring.
(h) The wattage or ampere ratings of each outlet for noninductive loads and the volt-ampere rating of each unit or transformer for electric discharge lighting.
(i) The location, voltage, and H.P. rating of every motor and the K.W. rating of every generator. The type and code letter of every A.C. motor shall be given unless otherwise satisfactory to the Department.
(j) The location and K.V.A., or equivalent rating of each transformer, capacitor, ballast, converter, frequency changer, and similar equipment and the location and ampere or wattage rating of other appliances of the noninductive type.
(k) Details of panelboard, switchboard, and distribution centers, showing type and arrangement of switches, overcurrent devices, and general control equipment.
(l) Panelboard and switchboard schedules showing wattage and amperage, the number of active branch circuits to be installed, and the number of spare branch circuits for future use. This shall include identifying the circuits to which the outlets are connected.
(m) The existing load, as calculated in accordance with Articles 210 and 220 of the C.E.C. or by other methods satisfactory to the Department, shall be indicated for existing installations having alterations or additions made to them. (Amended by Ord. No. 172,593, Eff. 6/28/99, Oper. 7/1/99.)
Other additional information as the Department may consider necessary for proper enforcement of this Code.
(o) On all occupancies indicating location, rating and method being served for all new and existing power distribution equipment. (Added by Ord. No. 172,593, Eff. 6/28/99, Oper. 7/1/99.)
(p) Any or all engineering calculations as applicable for the installation. (Added by Ord. No. 176,775, Eff. 8/1/05, Oper. 8/1/05.)
(q) Interconnected wiring between all devices in each branch circuit from any panelboard or switch-board to the last device or load. (Added by Ord. No. 176,775, Eff. 8/1/05, Oper. 8/1/05.)

BTW the City Amendments have some good stuff in them; e.g., the "proper" ambients to use.

 

[dkidd]

LA City does not allow fuse let through

It seems that is a reference to item F6. What the checklist is saying is that a short circuit analysis is required, and you can't use the old up over and down method of calculating faults through current limiting fuses. The reviewer may be misinterpreting this.

 

[dkidd]

so to avoid changing out all panel-boards we installed fused mains.

I'm guessing this is a continuation of http://forums.mikeholt.com/showthread.php?t=138813

Did you find UL listed series ratings for the fuses and the existing panel breakers and submit the documentation with the plans?

 

[cowboyjwc]

I'd ask for a specific Code reference or a copy of the written policy. The only way this makes sense to me is if the reviewer is referring to current limitation during short circuit conditions -- the "up, over, and down" approach. The up, over, and down method for fuse/breaker systems went out of favor 15 or so years ago. Have you done fault current calculations? If the panels are reasonably new you should be able to series rate with the fuses, but if I was the reviewer I would expect to see calculations to justify the rating.

I would guess that you're right.

 

[stuartdmc]

I'm guessing this is a continuation of http://forums.mikeholt.com/showthread.php?t=138813

Did you find UL listed series ratings for the fuses and the existing panel breakers and submit the documentation with the plans?

You Are Correct.

The City's Electical Plan Check Corrections List, states to provide a short circuit analysis including motor contribution. Fuse let-thru is not acceptable. Is he misapplying the is section?

We installed Main Fuses and now we have a problem. I'll ask that the engineer of record provide a short circuit analysis as to provide a series rating for the down stream breakers.



Stuart

 

[dkidd]

He does not seem to be misapplying the section. It is not a calculation issue so much as a UL listing. You really need to look up the circuit breaker manufacturer?s series rating information.

 

[stuartdmc]

He does not seem to be misapplying the section. It is not a calculation issue so much as a UL listing. You really need to look up the circuit breaker manufacturer?s series rating information.

We have, (3) units have GE panels and branch breakers, (2) have Square D. and (1) has Crouse Hinds all rated for 10k AIC. the Fault current at the meter is 33kaic

All the units are retail units, lighting and plugs only.

Does Motor Contribution apply? we don't have any motors other then the AC equipment?

The section is applying to motor contribution when it states Fuse let-thru is not accepted?

 

[dkidd]

6. Provide short circuit analysis including motor contribution. Fuse let-thru is not acceptable. _______________________ ______________________________ (110.9 & 10, 93.0207)
7. If series rating is used for short circuit protection:
a. Indicate the series combination interrupting rating of overcurrent devices. Identify on the plan, the fuse class and the circuit breaker manufacturer, model designation, type and electrical rating used as part of series rating. Include manufacturer specification sheet(s).
b. Series combination interrupting rating shall not be used when the second device in the series is subjected to a total connected full load motor current of more than 1% of it=s AIC rating.
c. Motor circuit protectors shall not be used as part of a series combination interrupting rating.__ (110.3, 93.0402)
d. If series combination ratings are used, provide a cautionary label to the series rated device cover stating ACaution - Series Rated System _________________ A available. Identified replacement component required.@ (240.86, 110.3, 110.22, 93.0402, UL Recognition Directory)

 

[rbalex]

The Electical Plan Check Corrections List, F.6 is a misapplication of CEC 110.9&10, LA City's Muncipal Code 93.0207 and the LA City Amendments since none of them call for it specifically. Section F.6 should also reference 240.86(A); it does call for an engineering evaluation, but once submitted as such, it should be accepted. They could reasonably require it to be a PE evaluation.

 

[stuartdmc]

6. Provide short circuit analysis including motor contribution. Fuse let-thru is not acceptable. _______________________ ______________________________ (110.9 & 10, 93.0207)
7. If series rating is used for short circuit protection:
a. Indicate the series combination interrupting rating of overcurrent devices. Identify on the plan, the fuse class and the circuit breaker manufacturer, model designation, type and electrical rating used as part of series rating. Include manufacturer specification sheet(s).
b. Series combination interrupting rating shall not be used when the second device in the series is subjected to a total connected full load motor current of more than 1% of it=s AIC rating.
c. Motor circuit protectors shall not be used as part of a series combination interrupting rating.__ (110.3, 93.0402)
d. If series combination ratings are used, provide a cautionary label to the series rated device cover stating ACaution - Series Rated System _________________ A available. Identified replacement component required.@ (240.86, 110.3, 110.22, 93.0402, UL Recognition Directory)

Ok.
We have provided all the above listed information. We have proven that the T rated fuses are series rated with the down stream CB's. So, why then aren't Fuses acceptable?