Home electricity question

[Jeff7]

Originally posted by: Modelworks
That sounds like the feed from the meter or street is not large enough for the load.
I would start by contacting the utility company and tell them them what you are seeing.
If its that old it could be loose wiring.

Or my landlord. It's an apartment.

And the wiring needs to be redone. Except for a few fresh new circuits, all of the outlets are two-prong.

And it needs new insulation. And the washing machine is older than me. And.....

Just so long as the building isn't going to burn down, that's all I need until I can afford something better.
I'm wary of the landlord raising rent if I deliver a long list of recommended renovations.

 

[skyking]

Originally posted by: AlienCraft

Originally posted by: ViviTheMage
check how many amp's its pulling..typically it'll flip your 20 amp breaker because your heater is 18-20 amps itself.

If I build a house, I want to do 30 amp breakers everywhere , expensive...but worth it.

No you don't. You think you do, but you have no idea what you're talking about.
Just compare a roll of 10/2 w ground to a roll of 12/2 w gr, because all your wiring will need to be 10 ga. Then you'l;l have to buy switches and duplex outlets sized to handle 10 ga wire. They aren't cheap.
More than likely, what you want to do, is learn about residential wiring, the National Electrical C, and local electrical regulations, and then decide what is practical.

I will only add that the net result of 30A/10Ga circuits for common wall outlets is greatly reduced safety.
The 15A standard matches the typical loads, and more importantly the cords on most high load appliances such as space heaters, blow dryers, etc. If one of those devices has a catastrophic failure it can turn the cord into a huge source of fire that may never throw that 30 amp breaker!
Adding more circuits is the safe way to go. Match the breaker and wiring to the typical load for safety.

 

[Elstupido]

30 amp lighting or receptacle circuit is not allowed by the NEC, ever. And for good reason.

 

[spidey07]

Originally posted by: skyking
I will only add that the net result of 30A/10Ga circuits for common wall outlets is greatly reduced safety.
The 15A standard matches the typical loads, and more importantly the cords on most high load appliances such as space heaters, blow dryers, etc. If one of those devices has a catastrophic failure it can turn the cord into a huge source of fire that may never throw that 30 amp breaker!
Adding more circuits is the safe way to go. Match the breaker and wiring to the typical load for safety.

Agree, but isn't 120/30A slotted so that it won't fit into your typical commercial/residential 120v/15 or 20a receptacle? NEMA is there for a reason, keeping people from doing stupid shit.

 

[Elstupido]

Spidey, yes, 100% correct. Put a 30 amp load on a receptacle rated 20 amps, and you are going to see a nice electrical meltdown and a bit of fire.

 

[Evadman]

Originally posted by: Elstupido
30 amp lighting or receptacle circuit is not allowed by the NEC, ever. And for good reason.

Really? Not that I am saying you are wrong or anything, but I didn't see that when I perused the code. I put a 30 amp receptacle on 10 gauge in my garage for my plasma cutter, since it pulls 22 amps by design. It is a 'portable' unit that is not designed to be hard wired. Not sure how else you could hook it up, since I followed the manufacturer's instructions.

It has a 30a breaker in a 100 amp sub panel that feeds my workbench. My workbench has 4 separate circuits, 1 30amp 3 20amp. AFAIK, it is built to (or better) than every code I could find.

Originally posted by: Elstupido
Spidey, yes, 100% correct. Put a 30 amp load on a receptacle rated 20 amps, and you are going to see a nice electrical meltdown and a bit of fire.

Well, hopefully you see a tripped breaker.

 

[Scarpozzi]

As stated....figure out where you want your space heaters and get an electrician to run you some new circuits.

Edit: And mark them so you'll know which ones are separate.

 

[Loreena]

10ga is silly since most wire is rated to 600V use 240VAC. Most electronics today will run 100-240V. A 16 gauge power cord will handle twice the wattage...

It does little good if your appliances are 120 though but since you can split phases with a small breakout box or distro and have two 15A 120 circuits on a single 15A double pole feed from your box. Heaters and Irons use HPN which is high temp jacket and very burn resistant. If you short even a 16AWG HPN it SHOULD trip a 30A single pole breaker unless it's a federal pacific no trip. But if you gradually increase the amps on a long term basis the cord will get overheated and probably burn something. Just like a frog in a pot heated up...

Don't fool with wires if you don't know the basics or you may wind up with a house on the ground.

 

[Elstupido]

Evadman, I was referring to a 110 volt standard 15 amp rated normal house hold receptacle, placed on a 30 amp breaker. It is perfectly fine to run a 30 amp circuit to a dedicated 30 amp rated receptacle for use with a higher amperage draw appliance such as your plasma cutter. It's good.

"Well, hopefully you see a tripped breaker."

And why would a 30 amp breaker trip while the 15 amp receptacle is smoking from a 30 amp load? These are the things that burn houses to the ground.

 

[Elstupido]

Loreena, 600 volt rating has nothing to do with amperage, it just means you could use that wire in a 480 volt 3 phase industrial application.

The main problem is the rating of the female contacts where the male plugs into. This is the weakest part of an electrical system. And yes I do believe the high temp wire will take 30 amps without melting the insulation.
Problem is the receptacle contact strength, which can't handle the heat from over amperage. I have seen so many burnt up receptacles from this, that if you had seen them, it would scare you, and make you go out and buy a smoke detector and a fire extinguisher.

 

[Loreena]

Voltage has everything to do with it. Since real work (watts) is the product of volts and amps you can use the same size wire to do twice the work. A single 14ga conductor can feed four houses or more on top of the pole transformer because it's carrying 7000-16000 volts.

 

[Elstupido]

True, volts times amps equals watts. 15 amps times 7000 volts equals 105000 watts. No matter what you do though, 14 gauge wire is still only good for 15 amps (whether 12 volts, or a million volts) according to the NEC.
Voltage rating on building wire is typically 600 volt because it can be used on 480 volt 3 phase industrial systems. Your normal cord ratings for household appliances is 300 volt, because you will not exceed 240vac, and is still governed by the laws of physics when it comes to ampacity for a given wire size and material of the conductor.

 

[Evadman]

Loreena, you are confused like I was because Elstupido is not explaining himself well. For me, he was saying 30a rated everything EXCEPT the wall outlet. Of course that's bad since the outlet is not rated for 30 amp. But Elstupido only said 'recpticle', not '15 amp household recepticle'.

For your question, Elstupido is saying that the insulation is rated for 600 volts before breaking down (leaking voltage). You are absolutely right that voltage is very important in determining how many watts are available to an electrical system. And as you stated, the wire itself is rated for a certain amperage, and the voltage and amperage together are what matters.

you are agreeing, but explaining poorly. Long story short:
Insulation on most household wiring is rated for 600 volts
14 gauge wire is rated for a 15 amp circuit
Thus a 14 gauge wire with 600v insulation can carry 15 amps at 120v, 240v or 480v without an issue. That also means it can do 2x the amount of 'work' (measured in watts) at 15a/240 as 15a/120v. Or 4 times the work at 480v.

Originally posted by: Loreena
you can split phases with a small breakout box or distro and have two 15A 120 circuits on a single 15A double pole feed from your box.

Remember, you have to be careful in how you do that. It is against code to have 2 hots and 1 neutral of the same size, even if phase split AFAIK. Even though we all know that 2 15a circuits fed from a double pole breaker should be phase shifted 180 degrees, thus canceling out to 0a on the neutral line assuming equal load, it is still not allowed.

 

[Loreena]

480V is three phase and that's I * R * 1.73 * PF if I remember correctly.

I've used boxes taking two hots and providing 20A circuits with a neutral legally in clubs for the dj's amplifiers. Most people would not know about them or want them in their houses though.

For cords, just use SO (not SJ) and you're good (SO = 600V).

For the outlet if you use 30A your recep should be 30A. Dike off the (smaller) plug and replace with the correct plug to be compliant.

 

[Elstupido]

Evadman, I am a master electrician with a ton of years experience, so sometimes I have problems explaining things to laymen, in everyday terms.
3 wire circuits, (2 hots sharing one neutral at 240vac) are used every day in wiring buildings. 0 volts on a neutral with a balanced 3 wire load is very desirable. Even better with a 4 wire circuit on 3 phase, and is perfectly ok with the NEC.

 

[Loreena]

Do you have three phase power at your house? That's really rare. The guys that do cheat with a converter or use a generator. I don't think most power companies will install it to your house even if you have three phase distribution lines overhead.

 

[Elstupido]

Loreena, why go to the expense of 600 volt wire when you will never exceed 240vac in a household?
The voltage rating has absolutely nothing to do with amperage rating! Granted, you do need at least 300vac rating when using 240vac, but unless you are using 480vac, 600v cord is a waste.

Insulation is rated for voltage because of the electrical pressure, and possible leakage due to higher voltages.

 

[Loreena]

600V cord has thicker insulation and is more durable when you have people rolling carts over the cords, etc. Of course 300 is fine for 240V.

Don't get me started on fuse ratings though.

 

[Evadman]

Originally posted by: Elstupido
3 wire circuits, (2 hots sharing one neutral at 240vac) are used every day in wiring buildings..

Not where I live, though it may be NEC. (I am more up on local than I am on NEC) I had to run 2 10 gauge hots and 1 8 gauge neutral for a 30a load for my A/C. I thought it was stupid as technically a 20 gauge neutral would carry the load, since the load should be 0 amps.

I am not a master electrician like you said you are, I am a mathematician by trade I suppose. But I have done my fair share of wiring, and have never (so far) failed an inspection. Not that it really matters, since I have only had a half dozen projects inspected unlike the thousands you have probably had. I would be closer to the general contractor that doesn't specialize in anything, but knows lots about everything. But not everything about everything. That is why if I am not sure, I always say 'AKAIK' so people like you can extend my knowledge, and others know that I may not be 100% correct

 

[Elstupido]

I said nothing about having 3 phase at a house. I am talking about commercial and industrial wiring applications.

And there are plenty of 20,000 square foot houses that do have 3 phase feeding them, though it is very rare

 

[Loreena]

480 was mentioned several times and if you have it then you have three phase. Your lights would be 277 as well. It's a good system and you just need a transformer for 208/120.

 

[Elstupido]

Evadman, now that has to be one of the dumbest things I have EVER heard coming out of a building dept. For one, I have never seen a small ac even needing a neutral, much less upgrading the neutral to 40 amps.

As a general rule on services and feeders, the neutral load can be derated to 70% and even more according to the neutral derating calculation provided in the NEC.

 

[Loreena]

What if the relay transformer has a 120V primary?

 

[Evadman]

Originally posted by: Elstupido
Evadman, now that has to be one of the dumbest things I have EVER heard coming out of a building dept.

My township is pretty fvcking dumb, you will hear no arguments from me on that.

 

[Elstupido]

Loreena, the mention of 480 volt was stated as to why wire is rated at 600v. Most commercial, and residential 3 phase services are coming in at 208v. Only large buildings will see reduced wiring costs associated with 480v. And yes, in these buildings transformers are used to provide 120v outlets, etc.