Gauge & type of wire

[WoodNotOil]

I am getting ready to buy the wire/cable to wire up my aquastats, relay, and pumps for my heat storage tank. Should I be using 14/2, 12/2, etc. Should I use aliminum bx, metal clad, steel armoured? Just too many choices. I would like whatever is least expensive or easiest to work with. Thanks for the help.

 

[pybyr]

I'm not a licensed electrician, although I've done a lot of wiring work over the years and studied up on the Nat'l Electric Code each time in order to try to be in general compliance (even though I am not strictly subject to it for my own work in the boonies). And as an additional disclaimer- the last version I really read up on was the 2005 version. But part of why I do my own work (in addition to frugality) is I actually sleep better with what I install, and how I do it, than a _lot_ of what I have seen done by licensed "pros..."

14/2 should easily handle the amperage for any single device of the types you're talking about, although not necessarily for a feed from the breaker panel to your system as a whole. That said, un-knowledgeable inspectors (and even contractors) tend to wig out when they see anything other than #12 being used, even where it's legit for certain uses under code, and the cost differential may not be that big.

BX is long gone, and for good reason- but the stuff you still see around that resembles it is the aluminum "MC" That's what I tend to see used in professionally done heating installations. I've used it for certain applications. It's more expensive than the vinyl-jacketed romex, so assuming you're working in a cellar, I'd be inclined to run romex along the ceiling (on "1 by " "runner boards," so it isn't hangin' loose from joist to joist), and then transition to the MC, using appropriate boxes and clamps, only for the final "drop" to your various controls, pumps, etc.

Since you're in VT and I'm in VT and since your system is pretty similar in some ways to what I am aiming to do eventually, I'd be more than happy to discuss more details with you some mutually- convenient time on the phone if you want to PM me with your phone #

 

[Nofossil]

For anything that's carrying 110vac, I use romex in the walls and tha aluminum jacketed stuff at the boilers and circulators - where it's exposed to damage. I have a 15 amp circuit for my boiler room. That allows the use of 14 gauge wiring, which is MUCH easier to deal with in small things like circulators. I did use 12 gauge for the long run from the breaker panel to the boiler room, but everything in the boiler room itself is 14 gauge.

For the thermostats and aquastats, as long as they're using 24vac you can use doorbell wire or other small gauge stuff. I use 8 conductor ethernet cable for a lot of my sensors and low voltage relays.

 

[Chris S]

Nofossil makes a good point. 14 gauge is much easier to use when working on the pumps, relays etc. .... if you are using a 15 amp circuit. You cannot run a 20 amp circuit which requires 12 gauge wire and then step down to 14 gauge. You can run 12 gauge wire on your 15 amp circuit if you choose. Thermostat wire - 18 gauge is common for everything else. we keep rolls of 18-2 and 18-4 on our trucks for this purpose. Also, as nofossil says making up your final connections where things can get damaged with mc (netal clad) is code. BX is still around, but much harder to work with. Romex, or SJ cord is not permitted. I did have someone tell me in a County North of me that " Everyone does it with romex around here" Last I checked the " National Electrical Code" covered that County too. My concern is safety, and compliance. Liability is a huge issue today. I've been to big fires, and the insurance companies are lokking for someone to help pay the claim, someone who didn't do something right.
NY doesn't have state licensing. I have mixed feelings on this. Orange County where I live started county electrical licenses this year, I think a very good thing, but even if the work won't be inspected we should still do it by the book.
Chris