Electrical wiring advice needed

By the way - in Canada NMD90 is approved for "damp" but not "wet" locations - so that's likely why it is deemed to be OK here in a conduit above ground (like for running wires up the wall to exterior lights)

Reply to
clare
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OK - it is a DAMP location - not wet in Canadian code, and NMD90 cable is approved for installation in "damp locations" in Canada.

No I am not. But as just stated above, nmd90 in Canada is approved for use in dry and "damp"ocations, but not wet. A properly installed protective conduit protects the cable from "wet" although it may allow the cable to be "damp" - and that passes code in Canada.

This iosn't a code document - but from Southwire's canadian website -

-

? Southwire?s Romex® SIMpull ® Type NMD90 cables may be used for both exposed work in dry locations or concealed work in dry or damp locations ? The maximum allowable conductor temperature is 90°C ? The minimum recommended installation temperature is minus 25°C for two-conductor cables, and minus 10°C for three-conductor cables (with suitable handling procedures) ? Material should be properly stored above 0°C for 24 hours prior to installation ? The maximum voltage rating for all intended applications is 300 volts ? Consult the Canadian Electrical Code1 for further information related to applications

Southwire?s Romex® SIMpull ® Type NMD90 cables meet or exceed the requirements of all applicable ASTM specifications, CSA C22.2 No. 48 (non-metallic sheathed cable), and the Canadian Electrical Code.1

Look up table 19 of the canadian electrical code for the permission to run NMD90 exposed in damp locations.

See also:

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Also see:
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and search for table 19.

Does this satisfy your objections??????

Like you said - code is different in different places. I am in Canada. In Canada NMD90 cable is approved for damp locations. Vertical protection conduit connected to weatherproof box for mounting a light is a damp location.

I have now given you the cites - so can we drop it now????

Reply to
clare

Cite that

Reply to
gfretwell

I've been looking for an official definition of "damp" and there doesn't appear to be one. other than in agricultural buildings where a livestock housing building needs a minimum air exchange -that is only described as "adequate" Under your NEC it is: "Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed pen porches, and like locations, and interior locations subject to moderate degrees of moisture, such as basements, some barns, and some cold storage buildings." while "wet" is : "Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather."

Also : "From the 2002 NEC Definitions

Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.

Location, Dry. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.

Location, Wet. Installations under ground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather."

Being enclosed in a water resistant, if not water proof enclosure (conduit) it does not completely comply with the description for a "wet" location.( unprotected locations exposed to weather) or ( locations subject to saturation with water or other liquids,) But that is under US regulations.

As you say - code in the USA and code in Canada are not the same.

And it seems pretty obvious my local inspector considered it to be only a "damp" location .Another inspector may not have agreed. Such is the ambiguity of an undefined or under-defined term, which is left to the interpretation of the inspector involved.

I believe in the USA under the NEC nmd-90 does not exist - nmd is 90 by default? And perhaps the limitations to it's use are different than in Canada.?

I also know that in some areas of the USA NMD cable is not allowed to be used at all - you must use armored cable or conduit. - and as in Canada where each province has it's own interpretations and "sub codes" the same is true in the USA - with the addition of even different cities in the same state having totally different interpretations /versions of electrical code.

Reply to
clare

There is no confusion here. Conduit outside is "wet". I was hoping you had a cite because I poked around a little in the CEC and I do not see the definition for locations. They seem to use "conditions" I will ask some of my Canadian electrical guys.

NMD90 seems to be the same as NM-b here and both are made by at least one company (Southwire). I suspect it is just marking.

There were only 2 cities that I knew of that did not allow NM (NYC and Chicago) and I think that is down to Chicago now. They have even started to soften. More states are going the way of Florida and just adopt the NEC with no local exceptions. We still have a few guys who try to squeeze their interpretations too hard but appeals to Tallahassee tend to pull them back onto the farm

Reply to
gfretwell

OK, so let's say I ignore code and install romex in conduit in a wet location. And over time water condenses in the conduit so the romex becomes and stays wet.

What's the big effin deal?

Does the insulation break down and allow electricity to flow between L1 and neutral?

Reply to
rick

The first thing you see is nuisance trips of the GFCI

Eventually the water can "wick" down the paper packing in the NM and drip into other boxes.

If you want the question I have not heard answered is why the manufacturers still use the paper in the first place. There is a listing for NM without paper, using plastic filler, called NM-c that tolerates more water than NM-b and less than UF but when you poke around, that comes back as UF cable in their catalogs so I assume they don't want to catabolize the UF business by upgrading NM-b to NM-c.

It must be available somewhere because it has a name, "barn cable".

NM-b (Romex) dry only NM-c (Barn cable) damp and dry UF (underground feeder) dry, damp or wet

Reply to
gfretwell

There is no paper in Canadian NMD-90 cable. I checked 4 different samples I have here, 14, 12, and 10 guage.

Perhaps that's why an associate who thought he could beat the system had to tear out ALL of the American NM cable he had used to wire his house - the inspector took one look - no CSA stamp on the sheath and he condemned the whole job. All of a sudden saving over 50% on his cabling costs wasn't such a great deal any more!!!

Like I said on a previous post (or more) on another thread - Canadian codes when it comes to safety tend to be much stricter than american requirements. Many things that pass UL don't come close to passing UL-c or CSA.

Reply to
clare

What packing do they use?

Reply to
gfretwell

Canada also, once you strip off the outer cover, there are 2 or 3 insulated wires and a bare ground, that is all, no paper or further insulation is required.

Reply to
FrozenNorth

I did some reading on NMD90. It appears there is no internal wrapper. Maybe that is why they give up 300v in the ratings. NM-b is 600v rated, NMD90 is 300.

Reply to
gfretwell

Does it make a difference, whether at 120 or 240 volts, for residential use it is well under the limits.

Reply to
FrozenNorth

The packing on Romex is to prevent "bruising" the conductor insulation if the cable is beat up during or after insulation. As I said to Clare, that may be one of the reasons why NMD-90 is only rated at 300v. It also uses a different conductor insulation than NM-b with no teflon jacket.

Reply to
gfretwell

Is the outer sheathing a different thickness, only guess I can come up with. I have pulled a fair bit of 15 and 20 amp rated cables, and to the best of my experience I doubt I could bruise the inner cables since I have never much more than maybe scuffed the outer insulation.

Reply to
FrozenNorth

The usual reason the insulation gets bruised is the installer gets a little too aggressive driving the staples. You are just "supporting" the cable, not torturing it.

Reply to
gfretwell

Probably true, not sure though, I have driven the staples, two hits with a hammer and they are usually in close enough to hold the cable, why give two extra hits. :-)

Reply to
FrozenNorth

What packing??? There is no packing. There is 2 or 3 insulated copper wires and one bare copper wire inside a plastic sheathing. No paper, no string, no "filament" of any kind. Not like our old Romex with the impregnated cloth covering and rattan wrap around the individual insulated conductors.

Apparently in the USA you are using a different product, manufactured to a different standard. It's not just a different stamp on the outside sheath.

Reply to
clare

Which is still well over the required rating for a center tapped single phase 120/240 volt electrical supply.

Reply to
clare

Well over? 250v (the max in the 240v standard) is more than 80% of the rating Maybe this is a case where Canada is not as safe as the US.

600v is standard for all conductors used for general wiring here.
Reply to
gfretwell

Actually peak voltage in a 240V AC circuit is 340V.

Reply to
trader_4

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