NMD90 vs AC90 (BX): Which Cable Do I Need?
Share
If you're finishing a basement, wiring a garage or adding a circuit, the two cables you'll see most often in Canada are NMD90 (often called Loomex or Romex) and AC90 (often called BX). They carry the same job, but they're built differently and they belong in different places. Here's a plain-language comparison to help you plan, and then buy only the length your project needs.
The quick answer
- NMD90 is the everyday non-metallic sheathed cable for house wiring, mostly run concealed inside walls and ceilings in dry or damp locations.
- AC90 (BX) has flexible interlocked aluminium armour, so it's the usual pick where a run is exposed or needs extra mechanical protection in a dry location.
- Neither is for wet locations, outdoors or direct burial. Those jobs need a cable rated for them.
Side-by-side
| NMD90 (Loomex) | AC90 (BX) | |
|---|---|---|
| Outer layer | PVC jacket | Interlocked aluminium armour |
| CSA standard | CSA C22.2 No. 48 | CSA C22.2 No. 51 |
| Conductor rating | 90 °C | 90 °C |
| Voltage rating | 300 V | 600 V |
| Bonding conductor | Bare copper | Bare, inside the armour |
| Typical places | Concealed in walls and ceilings, dry or damp locations | Exposed or concealed runs in dry locations: basements, garages, workshops, service rooms |
| Mechanical protection | Needs protection where it could be damaged | Armour gives built-in protection |
| Wet / outdoor / buried | No | No |
When NMD90 makes sense
NMD90 is light, easy to pull and quick to strip, which is why it's the standard for residential branch circuits. It's a good fit for lighting and receptacle circuits behind drywall, kitchen and bathroom renovations, and secondary suites. In unfinished areas where the cable could be hit or damaged, the code expects it to be protected.
When AC90 makes sense
AC90's armour protects the conductors from impact and abrasion, so it's common in unfinished basements, garages, workshops and utility rooms where the cable runs on the surface. It's also widely used in light commercial work. Use connectors made for armoured cable and anti-short bushings at every cut end.
Choosing the size
- 14/2: two 14 AWG conductors plus bonding, typically for 15 A lighting and receptacle circuits.
- 14/3: an extra conductor for three-way switching or split receptacles.
- 14/4: two extra conductors for multi-switch or multi-wire runs.
- 12/2: 12 AWG for 20 A circuits such as kitchen counters and workshops.
Always confirm the size against the circuit and the Canadian Electrical Code.
How much cable to order
- Measure the full route from panel or box to box, following the actual path along studs and joists.
- Add extra for box entries, turns and routing.
- Round up to the next available length.
All sales are final, so double-check your measurement before ordering.
Buy only what you need
Most small jobs don't need a full roll. At Wireco you can order AC90 armoured cable cut to length from 5 m to 70 m in 5 m steps, or NMD90 14/2 in a 50 m length, shipped anywhere in Canada.
This guide is for planning and product education only. Cable selection and installation must follow the current Canadian Electrical Code and your provincial or local inspection authority. If you're unsure, consult a licensed electrician.