14/2 Romex to replace 2 x 2.5mm^2

[moontang]

Hi folks, visiting the States and thought it might be good to bring some wire back.  in my Thai condo, the 15 year old ac has 2x2.5mm on a dedicated 20 amp circuit..no ground..but box is grounded.  So gearing up for eventual new 18000 btu ac...and want to ground it...will 14/2 with a ground work well?  Would 12/2 be better?  The run will be 8 meters.  A 15 meter roll of 14/2 romex is 23 usd...which seems better than I could do at home pro, where any three wire can be scarce.  Thanks in advance!

[Crossy]

I am not an expert on the US wiring standards (I'm a Brit), but from my limited research.

 

14 gauge Romex shouldn't be on a breaker bigger than 15A, so for a 20A breaker you'll need 12 gauge (which is about 3.3mm²).

 

Your new 18,000BTU A/C will draw about 1.8kW (8A) when the compressor is running so in reality the 14 would be fine, but a 15A C-curve breaker may not withstand the start surge and using a bigger breaker, whilst it would be ok by the UK regs (on a dedicated circuit), probably isn't wise (you never know what someone will add later).

 

Is the Romex from the US rated for 220V AC?

 

To be quite honest, what you have (with the addition of a ground wire) is perfectly adequate assuming you're just replacing the A/C.

 

I wired all our A/C in 4mm² singles in conduit, they're all on 20A breakers (nothing bigger than 12,000BTU) but there's headroom for expansion.

 

[moontang]

Planning on keeping the same 20 amp breaker.  Just running a new ground might be better.   A 2.5 is a 14 gauge, as far as wire size, but I don’t think the 14/2 is approved for 240 volt.  I am even wondering about using a nice us extension cord in LOS...It says it is polarity specific...but it is nice and heavy..was going to use it with a power drill.

 

The existing ac is 18000 btu and working fine on a two wire...but my instructions on the hot water heater I put in must have said four times to not do a two wire install..so I used 3 x 2.5...and glad I did, but it was almost a fluke that homepro had the three wire..by the meter only.

[Crossy]

14 AWG is about 2.1mm² rather smaller (85%) than 2.5mm², as far as I can tell the NEC limits 14AWG to 15A.

 

If your extension lead doesn't have surge protection or a nice illuminated switch it will likely be fine on the 220V here. The amount of insulation required for mechanical strength far exceeds the thickness required for actual insulation. Note, I wouldn't apply the same logic to fixed wiring (Romex) is it's not intended to be bashed around on a workshop floor.

[moontang]

Good point about the size of 14...the chart was leading me astray, 13 would be much closer, but don’t even know if it is made.  so glad I didn’t make that mistake...probably going to get a roll of 2.5 and run a ground.  Are conduits necessary in a drop down ceiling?  Thanks, Crossy!

[bankruatsteve]

A ground doesn't make anything work better - it simply reduces hazard and potential injury from "touch voltage".  Conduits in the ceiling are recommended to keep mice and other critters from damaging the cable insulation.  If you don't have any critters and empty space (not used for storage) conduit is not necessary.

[moontang]

9 hours ago, bankruatsteve said:

A ground doesn't make anything work better - it simply reduces hazard and potential injury from "touch voltage".  Conduits in the ceiling are recommended to keep mice and other critters from damaging the cable insulation.  If you don't have any critters and empty space (not used for storage) conduit is not necessary.

It would certainly be a lot better for a desktop computer...used them 30 years, and never had voltage in the case until I lived in an ungrounded apartment.

[bankruatsteve]

9 hours ago, moontang said:

It would certainly be a lot better for a desktop computer...used them 30 years, and never had voltage in the case until I lived in an ungrounded apartment.

 

Right, desktop computers commonly develop a small earth fault (power supply).  The resultant touch voltage is not high enough to be harmful but certainly annoying.  A 3-prong plug in a grounded outlet will send the fault to earth and no more tingle.

[moontang]

Here is a good question for the two wire shower users.  Is an ungrounded ELCB as effective as a grounded one?

[bankruatsteve]

3 minutes ago, moontang said:

Here is a good question for the two wire shower users.  Is an ungrounded ELCB as effective as a grounded one?

 

Yes.

Adding:  Assume RCD is set to trip at 30ma (a common setting).  That will trip on 30ma fault whether grounded or not.  It will not trip on less than 30ma and which is enough to knock you on your ass.  That is where you want a grounded shower to keep that from happening.

Edited October 2, 2018 by bankruatsteve

[kamalabob2]

Sure are quite a few items I have brought over from the USA that are a challenge to source in Thailand. size 12 4E New Balance walking shoes come to mind. Quality socks from Costco come to mind. However grounded VAF wire is at ANY decent electric shop or Builders Merchants store in Thailand. Even in rural Buriram Bangkok Cable | Yazaki electric cable and other brands are in stock. Often however it is marked to reflect that in 2018, the size of the ground wire is the same as the other two wires. So you see VAF -G 2 X 2.5/2.5   on the label of the roll of cable.  In previous years many manufacturers of electric cable in Thailand would have the ground cable one size smaller.  The OP can safe space and weight in his luggage as he can easily get grounded cable in Thailand for a very fair price.  VAF that is only two wires is in stock in every Mom and Pop electric shop I have ever visited in Thailand. Grounded cable is available at the better stores in Thailand in my observation. 

Edited October 6, 2018 by kamalabob2

[kamalabob2]

HomePro would not be my first choice if price was a consideration. Fancy displays, air conditioned showroom, perky staff, easy credit terms are a bonus of Homepro. Lowest price on name brand tools or even basic name brand electric cable or building materials, that has not been my personal shopping experience. HomePro does employ excellent "sale sign" staff. Everything is a "sale'.  Even if the price is higher than the store down the street. It is a "sale" at Homepro. 

Edited October 6, 2018 by kamalabob2

[bankruatsteve]

10 minutes ago, Arjen said:

The ELCB will work, but the leakage current has to go somewhere. That means when not grounded, the leakage current will go through you. What gives at least a very unpleasant feeling. When grounded, as soon you switch the thing on, the ELCB will trip, As the ground wire is an easier way for the current than through you, you will not notice it at all. (not by feeling electricity, you do not have hot water....) 

 

A solution for many Thai sparkies to solve this tripping is removing first the ground wire. When that does not help an other good solution is bypassing the ELCB.

 

Arjen

Crossy has noted several times previously in this forum that "ELCB" (which detects hazardous voltage exceptions) are hardly ever used these days.  Even though a shower says it has "ELCB", it is actually an "RCD" which detects current faults.  Again, an RCD will not trip until the fault current reaches a pre-set level - usually 30ma.  This will occur whether a ground is in place or a human body carries the fault current.  For example, if you get a "tingle" shock from something, that means the something is not grounded and the current is less than 1ma.  If the something is protected by an RCD, the RCD will not trip because the fault is well below 30ma.  Let's say the fault is 20ma.  The RCD will still not trip but you will be knocked to your ass (which is good because it will stop the current flow).  Police tasers only put out a few ma of current to do what they do.  

[moontang]

4 hours ago, bankruatsteve said:

Crossy has noted several times previously in this forum that "ELCB" (which detects hazardous voltage exceptions) are hardly ever used these days.  Even though a shower says it has "ELCB", it is actually an "RCD" which detects current faults.  Again, an RCD will not trip until the fault current reaches a pre-set level - usually 30ma.  This will occur whether a ground is in place or a human body carries the fault current.  For example, if you get a "tingle" shock from something, that means the something is not grounded and the current is less than 1ma.  If the something is protected by an RCD, the RCD will not trip because the fault is well below 30ma.  Let's say the fault is 20ma.  The RCD will still not trip but you will be knocked to your ass (which is good because it will stop the current flow).  Police tasers only put out a few ma of current to do what they do.  

Isn't an ELCB built into the heater?  Isn't another switch required by Thai code that can't be reached from inside the bathroom?  Wouldn't an RCD be located in the service box?  Originally, I liked the idea of having the RCD as a part of the circuit breaker, but they are kind of expensive and don't seem to meet the requirement to have the safety switch.

[wayned]

I'm American and actually have a commercial electrical license, issued in Mississippi in 1976 where the only test was that your check didn't bounce when you paid for the license.  The shielding on standard "romex wire is very different than what you get here.  The wire here is more like "UF" cable available in the US which is more expensive than Romex.  Romex is classified as NM type cable.  Here's a quick blur from google"

 

"The most significant difference between NM cable and UF electric wire is the type of sheathing that is used. Although NM cable is covered with a flexible thermoplastic covering on the outside of the wiring, the strands of wire themselves are usually protected with little more than a paper wrapper. On the other hand, UF cable utilizes solid thermoplastic exterior covering, and each individual wire is also enclosed in a protective sheath. This is an addition to the regular insulation that is installed on the thin gauge electrical wire. Therefore, UF electrical wiring offers much better sheathing protection than the NM type and is rated for outdoor, in-ground, and damp-area installation. "

Romex

 

VS 

UF

 

 

Edited October 6, 2018 by wayned

[bankruatsteve]

10 hours ago, moontang said:

Isn't an ELCB built into the heater?  Isn't another switch required by Thai code that can't be reached from inside the bathroom?  Wouldn't an RCD be located in the service box?  Originally, I liked the idea of having the RCD as a part of the circuit breaker, but they are kind of expensive and don't seem to meet the requirement to have the safety switch.

All shower heaters (to my understanding) now contain RCD protection in the unit.  I don't know why they still label it as an ELCB as technically it is not.  I haven't heard the requirement for an external switch.  Many installations will use a "RCBO" as a main breaker.  That provides RCD protection for all circuits in the CU.  That makes the RCD in the shower unit redundant but if there is a best place to be redundant, that's it.  Again, I don't know of a requirement for a "safety switch" or even what that would be.

[anon2736434]

Not a good comparison really, UF wire would be much more expensive than the VAF wire mostly sold here for use in houses. Romex is good for 110-220 volts, and depends on the wire gauge you buy what breaker you can use. 20 amp breakers for 14-3 wire is used with no problems.