Distribution and use of electricity throughout the home. Electrical standards vary greatly worldwide, so providing your location in your question or your profile helps ensure you get answers that are relevant to you.

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12
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3answers
798 views

What is “knob and tube wiring”?

I assume this is some USA wiring system, am I right?
12
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4answers
1k views

What is this 110/24V 60Hz transformer in the breaker room for?

My friend sent me a photograph of this transformer, which is installed above the main breaker panel, with leads running from the panel into the transformer. The stamped labels read PRI. Volts: 110 ...
12
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6answers
20k views

What is simplest strategy to map circuits to breakers in the panel?

My breaker box is very poorly labeled and I want to figure out which circuits may have overloaded (or close to it) and which could reasonably handle a little more. In the past I have just tried ...
12
votes
4answers
26k views

When to use holes instead of side terminals to wire an outlet

This question comes from Shirlock's comment on this GFCI wiring question. When and why should you use the holes on the back of an outlet rather than the side terminals? I always assumed the holes on ...
12
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3answers
20k views

What's the minimum depth that an electrical box can recess into a finished wall? Does it have to be flush?

Do electrical boxes have to be flush to the finished surface? Can they recess any depth into the wall by as much as 1/8" or 1/4"? Edit: I appreciate everyone offering alternative solutions to ...
12
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5answers
13k views

Why do my new dimmable CFL bulbs hum?

I just spent $100 upgrading our dining room lighting from regular incandescent bulbs with a dimmer switch to a CFL friendly dimmer switch with specifically marked dimming capable CFL bulbs. At full ...
12
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6answers
52k views

Is using 15 amp components on a 20 amp breaker against code?

I have noticed in a few different houses in Oklahoma that 20 amp breakers are used, but all of the outlets and switches only seem to be rated for 15 amps. This goes against everything I know to be ...
12
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1answer
396 views

How to make this electrical main safe

An older home has a strung electrical main. The main connects with exposed lugs on the roof above the deck. Not only is the height and location unsafe, while working on the roof today I noticed that ...
12
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1answer
4k views

How do I know if my wiring is aluminium or copper?

In this answer, Chris has mentioned that, before replacing a worn-out electric outlet, it is important to know whether the building has an aluminium or copper wiring. How can I get this information? ...
12
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3answers
22k views

Can Romex (NM-B) be run through conduit?

A few days ago I asked an electrician if I could run Romex through conduit - he gave me a funny look and said "No, Romex is not allowed in conduit." When I searched online, there seems to be a wide ...
12
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3answers
39k views

What is the proper way to run wires along/across basement ceiling joists?

I want to add an electrical outlet in my unfinished basement. It makes sense to run the wire along the ceiling because that's where all the other wires are. What is the proper way to install NM ...
12
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5answers
75k views

What's the standard height for an outlet?

I am installing outlets in my patio room. What is the standard height recommended above the ground for these to be installed?
11
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3answers
3k views

Is this electrical junction up to code?

I was up in my attic a few days ago, and I noticed a pretty ugly electrical junction that wasn't in a junction box. Here's the pic: Is this up to code? FWIW I live in north Alabama, outside city ...
11
votes
7answers
41k views

Why Do 240V Circuits Not Require Neutral?

Someone told me that a 240V circuit does not require a neutral wire in the cable. Can anyone explain this phenomenon from the electricity perspective and generally explain why circuits do and do not ...
11
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4answers
7k views

How can I detect reverse polarity on an ungrounded receptacle?

Recently moved into a 1950s-built house and am swapping out some of the older receptacles. On one particular ungrounded circuit there are four receptacles. The first two are as expected - the two ...
11
votes
2answers
5k views

Can I change a 1-gang electrical box to a 2-gang electrical box?

I live in a house built in the 50's in Maryland, US. Each bedroom contains 4 electrical outlets - configured in two 1-gang electrical boxes on opposing walls. However, with all the modern ...
11
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3answers
2k views

What size extension cord should I use for multiple computers?

We're hosting a LAN party (several computers, 50+) and I had some questions about power draw; I hope this is the right place to ask. Currently, we're assuming each PC will draw an average of 3.5 ...
10
votes
8answers
12k views

Is there any legitimate reason you would NOT connect the ground wire on a circuit?

I've been doing some remodeling on my house and had the need to move some electrical outlets. While doing so, I noticed that the ground wire wasn't hooked up on any of the outlets in the circuit ...
10
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8answers
16k views

Does a homeowner need a permit for electrical work in Massachusetts?

Does a homeowner need to obtain a permit from the town in order to do electrical work on his own house in Massachusetts? The unofficial answers I can find online (e.g., this forum and the websites of ...
10
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3answers
2k views

What are the differences between these two receptacles?

Residential duplex outlets come in a variety of styles. The two most common seem to be: and Does it matter? Is the difference purely aesthetics, or is there any technical difference?
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4answers
3k views

Would running a new subpanel in parallel meet NEC requirements? If not, what should I do?

Background U.S.A. Voltages/power present. My house has a 125A Power Mains breaker at the street. A buried line runs from the street breaker to my main panel on exterior wall outside of house. The ...
10
votes
3answers
13k views

What is electrical code for number of wires in a breaker?

US, Georgia I am adding some new ciruits to add some additional outlets. The closest place is to run a wire to the main panel box. My question is, can I connect more than one wire to a breaker and ...
10
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1answer
2k views

During a lightning storm, what causes the lights to temporary cut off and on?

I know it is pretty common during a lightning storm for lights to temporary cut off and on, but where and how and why is this occurring? Is the transformer temporally shutting off power to prevent ...
10
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4answers
1k views

How do I use three-prong appliances when my outlets are mostly two-prong?

I am living in a house where most electrical outlets are two prong. There are a smattering of three prong, in particular where an addition was put on. Am I hosed when it comes to where I can plug in ...
10
votes
2answers
1k views

Can I use old abandoned iron pipe as electrical conduit?

I have an older house (1920) and I have been planning on doing some rewiring to get rid of some k + t stuff. Anyway, I just noticed today that there are some irons pipes that used to be part of the ...
10
votes
1answer
10k views

How exactly does a 3-way switch work?

I just finished replacing all of the switches and outlets in my apartment, after fighting a long war with a weird 3-way switch. Needless to say, I won, but I'm still trying to grasp the concept of how ...
10
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3answers
17k views

Do all wires on basement walls have to be in conduit?

I need to know if, when a basement is unfinished and an outlet is on the wall, is it required to put all wires in conduit?
10
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3answers
3k views

What do I do with receptacles behind built-ins?

When installing built-in furniture, what should I do about the receptacles on the existing bare wall that will be covered up by the built-in? How would I handle a receptacle covered by a bookcase ...
10
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5answers
30k views

Should I put a dimmer switch on a ceiling fan?

I have a ceiling fan on our bedroom's vaulted ceiling. Since we don't want 7' pull-cords, the speed is stuck at full-tilt, which is no good. The fan has separate switches on the wall for lights and ...
10
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4answers
63k views

What do I do if there are only two wires coming from my ceiling electrical box?

I'm about to install several Hunter ceiling fans. This will be the first time I've done anything electrical past changing a bulb. The instructions that came with the fan show three wires coming from ...
10
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1answer
14k views

Can I add a standard receptacle on a GFCI circuit

So, I want to add a receptacle in the bathroom (I tend to run out of batteries on my phone while crapping at the end of the day). There's a GFCI outlet on the other side of the crapper wall that ...
10
votes
5answers
9k views

Why would there be a 50 amp plug on a 30 amp appliance?

I have an old conveyor dryer, which my office purchased used some time ago, just sitting in storage. The dryer is for silk screen t-shirts and has a large heating element and a variable speed conveyor ...
10
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1answer
14k views

What is the correct way to wire a 4 prong oven receptacle?

I think I wired this the right way but I can't find an online reference that I trust enough to flip the breaker back on. This is how I wired it. Is this correct?
10
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1answer
823 views

Humming Ceiling Fans

I have two Harbor Breeze 52in. Builders Series Ceiling Fans. Under normal operation these fans are smooth and quiet. However, during power outages like we've had recently, I use a Devilbiss 6000 ...
10
votes
1answer
2k views

Should I install my own electrical service panel or hire an electrician?

I'm getting electrical service to bare land. This is not temporary service but permanent remote service to a pressure treated 6" x 6" post instead of a building. I already have covered the work to ...
10
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3answers
3k views

How can I determine the maximum wattage that I can hook up to a breaker?

All of my heating is on one breaker, 240V on a double pole breaker, each marked 20A (it's a small condo). I wonder how I can determine the maximum wattage I can hook up to that breaker.
10
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2answers
3k views

Can disconnected knob-and-tube wiring be left in place?

The house I recently bought (over 100 years old) has had almost all of its wiring replaced with a new elctrical board. However, in two cases the new wiring has been connected to existing knob-and-tube ...
10
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2answers
579 views

Where can I get a switch for a 30A circuit?

I would like to add a switch to a 30A plug, but I am having trouble finding one (they are all rated at 15a/20a). Is there a reason you can't buy 30A switches or is it called something different? To ...
10
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3answers
518 views

How should I rewire this situation?

In my dinning room, I have this: There is a wire run going up through the floor from the basement. It then goes outside the wall, around a stud (or studs, I'm can't tell there is more than one), back ...
10
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1answer
3k views

What is this drill guide/template used when fixing electrical sockets called and where do I buy one?

My dad used to have one, you use it as a drill guide/template when fixing electrical sockets, but I cannot find anywhere that sells them, and as I don't know the name Google is not much help! ...
10
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1answer
66k views

Why is my air conditioner tripping the circuit breaker?

Our air conditioner recently stopped blowing out cold air. When I went to check on it, I noticed that the outside unit wasn't coming on. We had had problems with ants in the contacter in the past, ...
10
votes
1answer
969 views

What are “termination points” and why do I need them on my electrical supply?

An inspection of my electric supply service on the outside of my home in Maryland said I need 3 termination points and two grounding rods. The grounding rods I can get but I have no clue about these ...
10
votes
1answer
9k views

How many wires is too many for an outlet?

I keep finding outlets in my house that are wired in ways I've never seen. Today's find is an outlet in a bedroom with 4 hots and 4 neutrals. All connected to one outlet using the push-in connectors. ...
10
votes
1answer
4k views

Is it “normal” for a vacuum cleaner to trigger an arc fault breaker?

We recently had our main electric service panel upgraded (from a 50 year old 100 AMP panel to a 200 AMP panel). As part of the upgrade, the electrician installed an arc fault breaker on the bedroom ...
10
votes
1answer
3k views

How to replace a standard 2-gang light switch with an electric dimmer switch

I'm looking for a some assistance in fitting a new electric dimmer light switch. I'm in the UK if that makes a difference. I am trying to replace my existing two-gang light switch with a LightWaveRF ...
10
votes
2answers
7k views

How should I address my bathroom's flickering lights and GFCI tripping mysteriously? (Schematic included.)

So I inherited a bit of a nightmare for wiring in my bathroom. I'll be calling in an electrician, but wanted to have an understanding of the problem first, as not to be ripped off, lead astray, etc.. ...
10
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3answers
2k views

How can I install a ceiling fan that needs a 4“ box where I only have a 3” box?

As part of a home renovation project I discarded my old ceiling fan and have bought a new one. When installing the new one the electrician tells me that I have a 3" junction box and that I'll need a ...
9
votes
13answers
44k views

When wiring outlets should I use pigtails or both sets of outlet screws?

I'm replacing the outlets in our house and pulled out one that had two black and two white cables. My first thought was that it was two circuits, one of them being switched, but then realized the tab ...
9
votes
5answers
29k views

Why does my shower switch keep burning out?

I have a Mira Shower 10.8 kW. My switch is a 45A switch. I have a 50A fuse for the shower. The shower uses 10mm2 cable. 9 months ago the switch sparked and refused to turn off and the fuse ...
9
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3answers
2k views

Why did my electric bill climb suddenly?

So we had a little mishap a couple of months ago involving some flooding. We had some folks come in and "dehydrate" our house. It involved lots of fans running for a couple of weeks. We expected ...