What is legal/UL

I am an electronics/software engineer

Now I have a project - for the US market - where we need to equip a few hundred appliances with a CT to monitor current. The appliances are connected to mains with a regular power cord plugged into a regular outlet.

So I need to split the phases in the power cord enough to get my CT wrapped around either the black or the white wire. The CT is split-core, so the cable doesn't even have to be cut off.

To make installation super-easy, I'm thinking I'd supply each site with a short (1-2ft) extension cord with the CT already on it. All I need to do is to separate the wires enough to get the CT in. I'd use one of those white extension cords that can be easily split.

The CT's have a UL mark, and are isolated. The extension cords are off the shelf, also with UL markings.

Would this be "ok" from a code perspective? If not, is there a different approach that would be better? All I need is to get the small CT around one of the phases, but I want to avoid sending out an electrician to every site.

Any ideas welcome.

Reply to
Andrew
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I am an electronics/software engineer with lots of experience in electronics but not so much in the legalities of high(er) voltage circuits.

Now I have a project - for the US market - where we need to equip a few hundred appliances with a CT to monitor current. The appliances are connected to mains with a regular power cord plugged into a regular outlet.

So I need to split the phases in the power cord enough to get my CT wrapped around either the black or the white wire. The CT is split-core, so the cable doesn't even have to be cut off.

To make installation super-easy, I'm thinking I'd supply each site with a short (1-2ft) extension cord with the CT already on it. All I need to do is to separate the wires enough to get the CT in. I'd use one of those white extension cords that can be easily split.

The CT's have a UL mark, and are isolated. The extension cords are off the shelf, also with UL markings.

Would this be "ok" from a code perspective? If not, is there a different approach that would be better? All I need is to get the small CT around one of the phases, but I want to avoid sending out an electrician to every site.

Any ideas welcome.

Reply to
Andrew

I think the legalities may be greater than you expect. Your main hope in doing this work legally is if you fall under corporate rule exception in which they take on liability. In most, if not all states, only licensed professional engineers can practice engineering or even call themselves engineers.This is specially true if Public Safetey is at stake. You need to get suitable legal counsel from a qualified practitioner.

Bill

Reply to
Salmon Egg

If it plugs in, "code" has nothing to say about it. UL, ETL, TUV, and others, are "listing agencies" who will certify safety. Depending on your customer you may or may not need any of these. Particularly if this gadget is only used by a trained technician and not left "permanently" connected, you're likely good as is. Note that splitting the cord (any modification) will nullify any safety listing but from what you've said here that doesn't sound like a big deal. When in doubt, ask your lawyer. ;-)/2

Reply to
krw

If the cord you refer to is the simple figure 8 2 wire cord then you will have no ground to the appliance and unless you are sure the appliance is double insulated and suitable for no ground then you have a problem.

Reply to
John G

The issue will opt come form the building inspector (a code thing) it will come from OSHA or CPSC. Safer would be if you could find a short cord that was listed with the conductors split to snap your CT around.

Reply to
gfretwell

A cable like the one you mention would be ideal of course. I've been searching high and low to no avail...

Parts for a cable like that is easy to get of course, and I could easily have a few hundred of those made, but what kind of qualification would it have to go through? Would a licensed electrician be able to "approve" my design, or would we have to submit it to some third-party testing agency?

Thanks for your insight.

Reply to
Andrew

Alas in the US it would have to be approved by OSHA and they usually want a listing from a nationally recognized lab (actually an OSHA thing).

What kind of venue will this be used in and can you call the users "qualified" (electorial professionals). I know IBM field assembled things like this and got away with it by putting stickers on them that said "for use by qualified personnel only", calling it test equipment.

This may actually be a lawyer problem more than a safety problem but isn't that always the way? ;-(

Reply to
gfretwell

I'm not concerned at all about practical/real-life safety. I know more about safety than most of the electricians I work with, but they have the formal license and I don't.

Remember, we're talking about a 1 ft regular extension cord. It's going to be indoor only, for this purpose only, and with a known load of ~100W, so it's not very exciting at all.

A licensed electrician would be allowed to put the CT in the fuse box or around a wire in the wall, right? He should also be allowed to change out the plug on an existing appliance? Wouldn't it be reasonable to think he could also make this little extension cord?

..but I guess reason have very little to do with it ;)

Reply to
Anders

Some do, some don't. The rules aren't as cut and dried as people are suggesting here.

If it has a known load, what do you need it for? ;-)

Is this thing going to be a permanent installation? If so, the extension cord idea isn't a good one. If it's just a piece of test equipment and trained electricians are going to be the only ones using it, particularly if you can control who has access, you really have no problems. If they're all employees of the same company, your exposure is even less.

Why would you even suggest such a thing? ;-)

Reply to
krw

I just need to know if it's on or off. The appliance is turned on/off with a switch that's on the appliance itself, so I just need to detect if there's current in the wire or not. The easiest place to run a wire to is where the appliance is plugged into the wall - it's impractical to run a wire up to the appliance itself.

So I'm not even interested in the actual current - just on/off.

The appliance is operated by employees in the facility, but they are not electricians or have any special education. The appliance is not really a permanent installation. It could theoretically be moved by the employees, but it's unlikely.

Think of it as a regular floor lamp - and all I need to do is to detect if it's on or off.

Reply to
Anders

As long as they're all employees, you're good to go. Just train them how to use the device properly. Seriously. You might give them some simple electrical safety course at the same time. Is there an occupational safety organization in this company? They'll likely have some hoops already laid out for you to step through.

Seems like an overly complicated solution just for that, but perhaps not if you're so worried about legalities.

Reply to
krw

It's a major corporation, so I'm sure they have all kind of safety people and policies around. They already know how to use the "lamp" - it's been there forever. Part of the requirement for my solution is that the employees doesn't need to know it's there. They just flip the "lamp" on like they've always done. No training.

I can add a big DON'T TOUCH tag, perhaps ;)

I just want to do this as correct as I can. Not sure what would be simpler than a plug-in cord/dongle/box between the "lamp" and the wall, but I'm open to ideas ;)

BTW, I did suggest a photo sensor on the lamp, but that was shot down since they don't want to run wires up to it...

Reply to
Anders

Sure, but not *that* lamp.

Who installs it?

;-)

I don't see you having trouble with the law. As I said, your employer's occupational safety group may have very different ideas, however. I would

*strongly* advise getting them on board as early in the cycle as possible.

Your solution is good, IMO. However, it's not my opinion that counts. From what you've said (and what I've understood), there are no legal implications beyond those any employee would encounter every day. If there is an accident someone will have a mountain of paperwork, in any case.

Reply to
krw

contact powermeters.com They have a power/volts/ current meter which has a plug in current sensor. I am sure that you could order these separately at a reasonable cost. I also recall seeing specific devices designed to fit your needs- plug in and with one lead straight through and the other in a loop into which you could fit a clamp-on ammeter. At least they could put you on the right track. What you suggest is workable but does involve code problems and getting around these might be more expensive than a batch of 'killowatt" meters.

However, why not use a switched outlet- change the lamp so that it cannot be switched at the lamp. The switched outlet could have an indicator light. This will be cheap but won't tell you that the lamp is actually on (may be blown) but that it is supposed to be on.

I can add a big DON'T TOUCH tag, perhaps ;)

I just want to do this as correct as I can. Not sure what would be simpler than a plug-in cord/dongle/box between the "lamp" and the wall, but I'm open to ideas ;)

BTW, I did suggest a photo sensor on the lamp, but that was shot down since they don't want to run wires up to it...

Reply to
Don Kelly

That URL takes me to Schneider, but I'll give them a call and see what I find can out.

That would be ideal.

That was on my list of proposals too. The employees know how to operate the lamp with the switch on it -- anything else would require training, and they don't want that.

Thanks for the ideas!

Reply to
Anders

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