Conduit seal dilemma
- Thread starter a.bisnath
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- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
What is the area classification? What is the cable type? (It should be marked something like "TC," "MC," etc.) Your discription has something of a "European" tone and I need a more clearification.
Clarification
Clarification
class1 division 2,cable is p.v.c. outer sheath does have mc written on it and a british standard number that is now faded,inner cores have varnished cambric insulation strips twisted around them,the transformer is out of the 40 metre loading radius,cable very stiff
Clarification
class1 division 2,cable is p.v.c. outer sheath does have mc written on it and a british standard number that is now faded,inner cores have varnished cambric insulation strips twisted around them,the transformer is out of the 40 metre loading radius,cable very stiff
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
There are still some incongruencies. Where is the facility itself located? The US? Somewhere else?
While the area classification may be documented Class I, Division 2 the cable is odd. A British Standard marking is not of particular interest, but ?steel wire? armoring is. It isn?t a recognized US domestic cable construction for the installation you described. This doesn?t at all mean it is a substandard product; only that it has not been certified to a US standard for the application. If it had been marked ?TC? though with a NRTL mark ? I wouldn?t bat an eye.
If British IP or CENELEC Standards are being used for this design or installation, as the ?40 metre loading radius? seems to imply, it would be a classic case of attempting to ?mix and match? NEC and IEC systems. Actually, it can be done, but it takes a great deal of experience to do it correctly ? and even then it often produces some odd results. Still safe ? but nonetheless odd and usually suspicious.
If we were permitted to assume the cable would otherwise be acceptable in Division 2, then no seal would generally be required at the transformer. If the cable were routed through or terminated in an unclassified location though, Section 501.15(E)(4) comes into play and a boundary seal would be required. This is extremely unusual for cables as opposed to conduits. The steel wire armored cable construction described is not considered to have gas/vaportight sheath because the interstices of the wire create a breach path ? even with the PVC jacket.
In the ?real? world, I don?t believe seals are necessary at all in the installation as I understand it; but that is definitely a non-authoritative opinion.
clarification and gratitude
clarification and gratitude
the platform was originally wired to american standards,in aluminium conduits ,sea blast 'ate conduits' even some with pvc coating on them,over the years(platform is 30 years old),started to change same to armoured cables, never had a problem,however 'because it works do not mean it is correct.
clarification and gratitude
the platform was originally wired to american standards,in aluminium conduits ,sea blast 'ate conduits' even some with pvc coating on them,over the years(platform is 30 years old),started to change same to armoured cables, never had a problem,however 'because it works do not mean it is correct.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Oddly enough, experience in a given industry is often how something works it's way into the NEC - even if the material or installation method wasn't compliant earlier.
Our neighbors to the north in Canada commonly use what is called TECK cable in Division 1. In my opinion, it's a better construction than "common" interlocked-armor Type MC, but it is recognized only as Type MC in the US. The subtle difference is TECK has an additional cable jacket underneath the armor that is neither required nor prohibited by the NEC.
There were moves a long time ago to get it recognized as a variant form of interlocked-armor Type MC that would be acceptable for Division 1 in the US - based solely on Canada's experience. It probably would have been accepted eventually - and should have, in my opinion.
However, with the introduction of MC-HL it will never happen - not because it shouldn't be; but because there is too much product protectionism involved and it affects a lot more than just the cable construction.
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