Clone 320.40 into 330

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msd

Senior Member
Re: Clone 320.40 into 330

If someone could explain to me how, by whatever mechanism, MC has some sort of immunity to damage from rough armor ends that AC somehow doesn't have, then I'll become a believer that everything is fine the way it is
inside ac cable is twisted/braded paper leaving conductors exposed to contact with the jacket.

inside mc cable the conductors are wrapped in a plastic jacket. sort of a pre-anti-short bushing

when properly installed in a prebushed compatible connector (ex. SpeedLock or Arlington L15A)the "plastic wrapping" acts as the anti-short bushing. the plastic wrapping should extend throught the insulated throat of the connector.

the connectors are ul listed for use without the anti-short bushings.

what i see all too often is mc cable that has been cut in the field with either "wire cutters" or "tin snips" and the plastic jacket cut or folded back before being placed in the connector. RED TAG for that !!!!

use a Roto-Split to cut your mc cable and bring the plastic wrap through the insulated throat of the connector and you have a code compliant and ul listed install.

that being said - i always use anti-short bushings with mc too.
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: Clone 320.40 into 330

Originally posted by msd:
when properly installed in a prebushed compatible connector (ex. SpeedLock or Arlington L15A)the "plastic wrapping" acts as the anti-short bushing. the plastic wrapping should extend throught the insulated throat of the connector
Can you provide any reference for that?

I have never seen any instructions or codes that require the plastic wrap to extend through the connector.

I do not believe for a moment that the plastic wrap is there to act as an anti short bushing.

NEMAs own statement about terminating MC makes no reference to the plastic wrap.

Originally posted by msd:
what i see all too often is mc cable that has been cut in the field with either "wire cutters" or "tin snips" and the plastic jacket cut or folded back before being placed in the connector. RED TAG for that !!!!
Red Tag?

What code section do you cite?

Unless the folded back plastic is interfering with the grounding of the MCs sheath I see no violation.

There are snips on the market specifically for stripping MC.

In my opinion you are trying to enforce your own preferences not actual code requirements.

Bob

[ November 17, 2004, 03:45 AM: Message edited by: iwire ]
 

peter d

Senior Member
Location
New England
Re: Clone 320.40 into 330

Sometimes local codes require the use of "rotosplits" and insulated throat connectors.


(Add) 13.8.10.6.2.3

A cable-cutting tool with controlled depth of cut shall be used in all MC cable installations.

(Add) 13.8.10.6.2.4

UL listed type MC cable connectors with insulated bushings and screw type cable attachments shall be used in all MC cable installations. Connectors shall be steel, not the cast type.
Taken from Rhode Island Fire Safety Code

The above rules apply to fire alarm system wiring only.

[ November 22, 2004, 07:55 PM: Message edited by: peter d ]
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: Clone 320.40 into 330

Peter I was unaware of that RI FA rule, thanks. :)

I am familiar with the strictly enforced color code and the "no wire nuts" rule. :roll:

It was not until recently that you could get permission to run MC, pipe was preferred.

Bob
 

peter d

Senior Member
Location
New England
Re: Clone 320.40 into 330

Bob,

You're welcome. :)

That was my reaction as well when I did my first fire alarm: :D

It's ok to wire nut 277 volt circuits together, but not 24 volt FA circuits. :confused:

Here are the specifics:

(Add) 13.8.10.6.5

Any fire alarm wiring between the fire alarm control unit and remote terminal cabinets or between remote terminal cabinets may, at the option of the installer, be a multi-conductor cable with each conductor numbered at two-inch (2") intervals. All wiring from a terminal cabinet(s) to an alarm device(s) shall conform to the color code specified before herein. Terminal cabinets with hinged, lockable red covers shall be provided at all junction points. All conductor splices or terminations shall be made on screw-type terminal blocks - wire nuts, butt or crimp type connectors shall not be used. All terminals within a terminal cabinet shall be properly labeled. EXCEPTION: Crimp-type connectors may be used on bonding conductors.

(Add) 13.8.10.6.1

All fire alarm system wiring within a building and between buildings in multiple building clusters shall be installed in metal raceway with steel couplings and box connectors or type MC cable rated as FPLP and 2-hour fire rated for penetrations by UL.

(Add) 13.8.10.6.2.1

All conductors shall be minimum #16 gauge solid copper, type thhn, thwn or tfn. All wiring shall be run continuously from device to device. With the approval of the AHJ, junction points may be made due to construction hardships where a continuous run would be impractical or when one of the exceptions to 72:6.4.2.2.2 applies, provided the requirements of ? 13.8.10.6.5.1 are met.
I'm sure you've been to the Providence Place Mall. There's miles of FA MC in there.

Out of curiosity, how do you do FA's in Mass? FWIK, every town seems to have their own code.

Edited to include ammendments, because I just found them.

[ November 23, 2004, 08:14 PM: Message edited by: peter d ]
 

jwelectric

Senior Member
Location
North Carolina
Re: Clone 320.40 into 330

Gentlemen
I had the good fortune of being at the seventy fifth Diamond Jubilee meeting of the IAEI in Orlando Fla. We were at lunch break and at the table beside where we were eating I overheard the discussion about AC and MC Cable and its use. To make this short and sweet they said that the biggest problem with MC Cable was that the installer?s way of cutting the amour. MC comes with a plastic wrap between the amour and the conductors and the use of lineman and diagonal cutters being used to cut the amour was the problem in the abrasion of the conductors.
The one thing to remember when making a proposal for a code change is that personal prefaces are not considered.
 
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