Rex's Home inspection book

[tonyi]

I was flipping through Rex Cauldwell's home inspection book while waiting in line at the Despot today and something caught my eye (generally great rogues gallery pics there of electrical horror shows too)

There was a pic of a 2-pole breaker with two black wires on it along with a statement that using a 2-pole on two distinct circuits was prohibited. It may be inconvenient to trip both at the same time, but I didn't recall anything in the code saying you can't trip more breakers than are minimally required.

 

[ryan_618]

Re: Rex's Home inspection book

Hmm...I would be interested in how Rex addresses multiwire branch circuits connected to the same yoke!

 

[tonyi]

Re: Rex's Home inspection book

Originally posted by ryan_618:
Hmm...I would be interested in how Rex addresses multiwire branch circuits connected to the same yoke!

I see it as a safety issue where the code is strictly a minimal thing and typically put multi-wires on a 2-pole by choice even when its not strictly required. So what if an extra breaker trips? BFD. In a system thats conservatively implemented and not "pushing the envelope" with a bazillion recepticals and lights on a branch, a trip should be an exceptionally rare event.

When one side of a multi-wire trips I don't want something bad (like an arc) on the other side continuing. There's also the issue of some naive person moving breakers around in a panel and putting both sides on the same leg accidentally. I've seen too many multiwires where the seperate breakers weren't side by side, or even on the same side of the panel.

 

[ryan_618]

Re: Rex's Home inspection book

Originally posted by tonyi:
So what if an extra breaker trips? BFD.

Well put!!!

 

[iwire]

Re: Rex's Home inspection book

tonyi

You can obviously wire things how you see fit, and I prefer that multiwire branch circuits are on consecutive breakers.

But there is no requirement that the breakers are on the same side of the panel or be on consecutive breakers, other than in the application Ryan brought up. (Multiwire branch circuit feeding one yoke in a dwelling unit)

It is OK for you to say BFD about extra circuits tripping, but I work for customers that would not be very impressed with that situation.

 

[roger]

Re: Rex's Home inspection book

I'm glad Rex only deals with home inspections.


Roger

 

[russellroberts]

Re: Rex's Home inspection book

I recently had an instance in a small resturant,that we had wired a couple years ago.
The owners placed 2 large coffee pots on a table and used the closest recep.The lights in this area happened to be on a multiwire ckt. with one feeding receps and one lights.In my infinite wisdom,I used a 2 pole breaker to feed these. When one of the coffee pots had a fault,the lights in that area also went out.Neither the diners nor the owner had much of a sense of humor about it. In this particular case,it was a big deal. Btw,I changed the dp to 2 single poles.

Russell

 

[roger]

Re: Rex's Home inspection book

Russell, the teenage daters that were in the booths would probably vote for you for president.

Roger

 

[tonyi]

Re: Rex's Home inspection book

Originally posted by iwire:
tonyi
It is OK for you to say BFD about extra circuits tripping, but I work for customers that would not be very impressed with that situation.

IMO, if uninterrupted service is absolutely critical for some specific application, then you run two genuinely seperate branches rather than multi-wire. ex. home based life support equipment like respirators, baby breathing monitoring gear, etc. The only real reason for multi-wire in any residential work is installation convenience and cost - both of which in reality are pretty minimal savings when the downside of possibly damaged cord/plug devices from a loose neutral are factored. My splices are good, but I have no control over who the next guy to work on something is

As I said previously, unless a multi-wire trip has been investigated and diagnosed as to why it occured, bad things could still be happening on the other leg if its allowed to continue running. If was a garden variety overload trip, no big deal - party on. If it was an arcing between the legs that burned through to the neutral and eventually shorted one out, then there's still a problem. I'd take iron clad safety over convenience in a residential environment any day. Commercial/industrial installations may have downtime constraints that residential (usually) doesn't.

 

[tonyi]

Re: Rex's Home inspection book

Originally posted by russellroberts:
I recently had an instance in a small resturant,that we had wired a couple years ago.
The owners placed 2 large coffee pots on a table and used the closest recep.The lights in this area happened to be on a multiwire ckt.

This is something I admit to being kinda fanatical about - I generally try to keep receptical loads and lighting loads on completely different branches unless there's some really compelling reason not to. I'll multiwire lights w/lights or recepticals with w/recepticals to do load balancing. Recepticals are apt to cause trips on common overloads, but keeping the lighting (a known and relatively fixed load) seperate means you're never going to be "in the dark" from simply plugging in too much stuff.

Maybe it takes a few feet more wire and an extra breaker or two, but the additional user friendliness of isolating lights from recepticals is huge when a an ordinary overload trip happens. If a dedicated lighting branch trips, then you KNOW something really went sour somewhere because it can't possibly be an overload trip (unless someone screwed 300W light bulbs in everywhere )

 

[Guest]

Re: Rex's Home inspection book

Why isn't a tie-handle required on all multi-wire branch circuits? If somebody is sloppy (or a DIY) they can open the neutral before the wye and get hurt. Safer yet to have a tie-handle on all multi-wire branch circuits. Require them to terminate in adjacent breakers too-- or at least on an adjacent buss pair. Not a big deal but worthy of erring on the side of safety.

 

[Ed MacLaren]

Re: Rex's Home inspection book

Why isn't a tie-handle required on all multi-wire branch circuits?

I don't get it. Why would anyone want to shut down three circuits if a fault or overload exists in one of them, or let's say, to replace a ballast or receptacle?

I also know many customers that would not be happy with that.

they can open the neutral before the wye and get hurt.

I don't understand this statement????

And I hope you are not suggesting that rules be introduced to accommodate "sloppy" electricians, or DIYs.

Ed

[ October 14, 2003, 06:30 PM: Message edited by: Ed MacLaren ]

 

[iwire]

Re: Rex's Home inspection book

Don R. has told me there is some action in the direction of requiring all multiwire branch circuits to have handle ties so that when we do lock out tag out we will know that we are working on a multiwire branch circuit.

I disagree with this strongly, I believe we could come up with some suitable marking requirements to help make it clear that you are working a multiwire circuit.

Lets think about this for 277 volt lighting circuits, already when you dump a single 277 volt lighting feed in a commercial office space you can lose 20 or 30 troughers.

Now if this happens to be on a multiwire branch circuit with handle ties you may put out an entire floor.

Now many of you will say run separate circuits, well have you had to deal with "value engineering"

The use of multiwire branch circuits in commercial spaces can result in large savings.

Fewer and smaller conductors, resulting in smaller or fewer raceways.

 

[roger]

Re: Rex's Home inspection book

The problem is the "What If" argument.

Those who are against "multi-wire circuits" always bring the DIYer, sloppy work, next electrican, (which doesn't hold water) or broken neutral into the conversation.

In reality they show there misunderstanding and in turn fear of a safe wiring method not to mention mother earth friendly.

Roger

[ October 14, 2003, 07:14 PM: Message edited by: roger ]

 

[iwire]

Re: Rex's Home inspection book

Originally posted by roger:
The problem is the "What If" argument.

I am with you there Roger.

What part of any electric work can we not "What If" to a point of danger.

What if some one takes the cover off a panel?

What if some one installs larger fuses in a fusible disconnect?

What if I run large conductors for voltage drop and someone comes later and puts a larger OCPD on these conductors?

Only qualified people should be working on electric equipment.

[ October 14, 2003, 07:33 PM: Message edited by: iwire ]

 

[renosteinke]

Re: Rex's Home inspection book

I have seen a lot of Rex's work, and he is quite competent.
It is possible that, considering his audience for that book, that he built some "trade practices" in as requirements. After all, a job worth doing is worth doing right!

 

[roger]

Re: Rex's Home inspection book

Reno, I agree. My first post was intended to be humor and it was poorly delivered (twice in one thread). I don't know if Rex meant "prohibited" as per code, but I agree it should not be done if not on a common yoke.

My vote goes to Rex.

Roger

[ October 14, 2003, 08:30 PM: Message edited by: roger ]

 

[Guest]

Re: Rex's Home inspection book

I agree with the value engineering angle. If the budget isn't there we may have to set aside our preferred practices and just stick with the code minimums and stick with the code allowances. Most of my jobs are two-handle and not huge so a handle tie here or there or an extra neutral here or there isn't going to break the bank. On large 3-handle jobs you would have to close up shop if you started insisting on extra neutrals.

Another reality is that qualified personnel are not the only ones to stick their fingers in outlets. It comes down to practical safeguarding and practical means value.

 

[big jim]

Re: Rex's Home inspection book

Come on, guys. The code is full of rules that deal with What if situations. S type screw base fuses, different size fuse holders for different classes of fuses. The whole idea of short circuit protection is about what if something shorts. The real issue is, "How far do we take it?" The current hot potato is AFCI, multi-wire may be next and who knows what else the future holds. At least in theory, the rulemakers consider the cost/benefit aspect when these things come up. I think I could make a case for handle ties in residential only.