Your minimum PPE for residential breaker box work

[ericsarratt]

How about just turning the power off ?

I do, but I can't pull the meter each time I work on my panel.

 

[ericsarratt]

Arc flash events are typically three-phase, but a single-phase event could occur.

Interesting.

 

[ericsarratt]

You should ask if they compared the use of undersized for a 200 service 6 awg on old worn out rusted transformers overhead 40 ft sized at 15kva 1 phase and the newer style 25kva with 80ft of 4/0 urd. I know both will blow up stuff but I want hard numbers and destructive testing with this equipment.

I wondered if this was the case.

I noticed that my aluminum SE cable looked a little small in the meter box. Do utilities use undersized SE cable in relation to the amps they provide?

 

[jim dungar]

So, for an electrical safety policy and procedure I can just say that my company has adopted NFPA 70e?

And, of course train employees in 70e.

Thank you. This is new to me.

NFPA 70E is a standard not a work policy, it tells you what things need to be done, but not how do them. There are many decisions your company needs to make in order to have an Electrical Safe Work Practices program.

 

[GeorgeB]

Do they have much 600v in NC?

In the "old days", 1930s thru 1990s or so, much of the textile industry and brick industry was 600V. IIRC, around 1963, The brick plant my father ran added a kiln, roughly doubling energy needs. CP&L (now Duke Energy) would not supply a transformer from their distribution line voltage to 480. My father had the option of 480 or customer owned transformer for 600. They went to the used equipment market and stayed with 600V.

Most of those plants are closed. With no knowledge, I suspect new plants are 480V.

The kilns I have seen were not heated with electricity. Natural gas, fuel oil, pulverized coal, and some experimental sawdust were main sources. Now that the furniture manufacturing is dead there also, I doubt the use of sawdust. Coal never took off in a big way. It's been 30 years since I walked through a brick/tile plant.

 

[Joethemechanic]

Do utilities use undersized SE cable

Most times you own the se cable. Utility only owns to the end of the service lateral

 

[Joethemechanic]

In the "old days", 1930s thru 1990s or so, much of the textile industry and brick industry was 600V. IIRC, around 1963, The brick plant my father ran added a kiln, roughly doubling energy needs. CP&L (now Duke Energy) would not supply a transformer from their distribution line voltage to 480. My father had the option of 480 or customer owned transformer for 600. They went to the used equipment market and stayed with 600V.

Most of those plants are closed. With no knowledge, I suspect new plants are 480V.

The kilns I have seen were not heated with electricity. Natural gas, fuel oil, pulverized coal, and some experimental sawdust were main sources. Now that the furniture manufacturing is dead there also, I doubt the use of sawdust. Coal never took off in a big way. It's been 30 years since I walked through a brick/tile plant.

Yeah I'm thinking the only time I've seen 600v was in Canada's "Chemical Valley"

 

[letgomywago]

I wondered if this was the case.

I noticed that my aluminum SE cable looked a little small in the meter box. Do utilities use undersized SE cable in relation to the amps they provide?

I'm talking utility owned wires. Underground standard is 4/0 urd overhead is 6awg triplex. The 6 awg is technically only good for 100 amps free air but it's common. The higher resistance lowers incident energy but overhead is usually shorter runs from a transformer than underground. There's more to the math because the supply of the transformer is often fused and there isn't 100% efficient transformers and other factors that affect arc incident energy.

 

[Joethemechanic]

I'm talking utility owned wires. Underground standard is 4/0 urd overhead is 6awg triplex. The 6 awg is technically only good for 100 amps free air but it's common. The higher resistance lowers incident energy but overhead is usually shorter runs from a transformer than underground. There's more to the math because the supply of the transformer is often fused and there isn't 100% efficient transformers and other factors that affect arc incident energy.

You know sometimes you sound really smart for a romex guy

 

[letgomywago]

You know sometimes you sound really smart for a romex guy

You get to wondering when cutting out your 30th can light of the day

 

[Joethemechanic]

You get to wondering when cutting out your 30th can light of the day

You are supposed to spend that time thinking about beer, pole dancers, and your favorite pro sports team

 

[letgomywago]

You are supposed to spend that time thinking about beer, pole dancers, and your favorite pro sports team

Nah I got a wife and kids that I think about but that just is more incentive to make it home without injury.

I'm a firm believer in a efficient but music free job so you wonder while working but you can hear the other guy say hand me up a drill in the attic or catch this wire I'm fishing.

 

[ericsarratt]

NFPA 70E is a standard not a work policy, it tells you what things need to be done, but not how do them. There are many decisions your company needs to make in order to have an Electrical Safe Work Practices program.

So the Electrical Safe Work Practices program is the policy and procedure? And the P&P says we utilize 70e as the basis of our ESWP?

 

[ericsarratt]

Most times you own the se cable. Utility only owns to the end of the service lateral

So, probably (I'll call Duke), I own the vertical cables in the weatherhead to the meter and Duke owns the horizontal cable between their pole which connects to the weather head.

I had the power cut off at the pole and the meter pulled to do electrical work inside the meter box. A knockout was missing and a birds nest was inside. I have been looking carefully at everything that is installed to make sure everything is sized correctly for the service amperage.

 

[ericsarratt]

So the Electrical Safe Work Practices program is the policy and procedure? And the P&P says we utilize 70e as the basis of our ESWP?

I did some googling and realized I am asking the same question. I'll get with my OSHA consultant to clarify. Thank you!

 

[Joethemechanic]

So, probably (I'll call Duke), I own the vertical cables in the weatherhead to the meter and Duke owns the horizontal cable between their pole which connects to the weather head.

Yeah, NEC only applies after that point. Sometimes called POCC (point of common coupling) Duke does not have to follow the NEC

 

[kwired]

I wondered if this was the case.

I noticed that my aluminum SE cable looked a little small in the meter box. Do utilities use undersized SE cable in relation to the amps they provide?

They possibly can and often will use smaller conductors than NEC will require.

Also if you are getting available fault current values from them - they aren't necessarily the actual value but rather a worst case estimation so to speak. Which is sort of ok when it comes to selecting withstand rating of equipment, but it can throw off results of incident energy for arc flash concerns.

 

[jim dungar]

So the Electrical Safe Work Practices program is the policy and procedure? And the P&P says we utilize 70e as the basis of our ESWP?

Pretty much yes.
The people that want just an arc flash study and labels really don't meet NFPA70E.

 

[hillbilly1]

They possibly can and often will use smaller conductors than NEC will require.

Also if you are getting available fault current values from them - they aren't necessarily the actual value but rather a worst case estimation so to speak. Which is sort of ok when it comes to selecting withstand rating of equipment, but it can throw off results of incident energy for arc flash concerns.

I was talking with an poco engineer, and he said they just use infinite buss in their calculations to give the customer.

 

[David Castor]

But, what about arc flash from the lugs at the top of the breaker panel? Even with the main breaker off the lugs are still active.

Still energized equipment with exposed live parts in my opinion. So PPE required. The "finger-safe" guards are good, but probably not safe against someone who loses situational awareness.

As a great man once said: "Do you feel lucky today?"