I was browsing a Home DIY website and in the electrical section came across something which puzzled me. (I'd post the link, but I've completely lost track of where it was now!)

A guy was asking about wiring a workshop. The reply included advice about whether to use 15 or 20A branches for the regular 120V receptacles. I know that 15A recepts. are allowed on a 20A branch in the U.S., but according to this reply the CEC requires 20A recepts. if the breaker is 20A. Fair enough.

It's the next part I can't figure out, because the response went on to say that it may not be worth wiring 20A branches, because of the need to re-plug all the existing 120V power tools with 20A plugs.

A 20A recept. will accept 15 OR 20A plugs. So why would there be a need to change any plugs? Am I missing something, or is the guy responsible for that reply talking out the back of his hat?

He was talking out the back of his hat... (among other things...)

Yes, both 125V and 250V 20A receptacles that I have ever seen will accept the 15A counterparts because of a T-shaped hole.

Then again... I've been wrong before...

Wooops!!!!

I was going through the threads under the "today's active topics" part...

Didn't notice this was under the Canadian Section!!

Sorry folks!

I was assuming that Canadian plugs are NEMA too. So I think your answer is correct.


[This message has been edited by Dspark (edited 09-05-2001).]

It might have been older info.I was not permitted to install them until the 94 code(the red one).I got 22 of those nice ARROW HARTS with the built in surge suppressors for free as they were shipped with some dialysis units from the States.Also our devices usually do have a NEMA,UL,and CSA markings but only CSA marked equipment and devices may be installed unless you call inspection.They come down and check for chassis grounding ,overcurrent protection and other common sense things.The cost is usually around $120 for small machines like money changers and pop machines ect.Quite a bid of our stuff is from the States.

[This message has been edited by frank (edited 09-05-2001).]

[This message has been edited by frank (edited 09-05-2001).]

[This message has been edited by frank (edited 09-05-2001).]

Same here Virgil:

I have some NEMA 5-20 (125V) and 6-20 (250V) recepts. here. These, and all the ones I've ever seen while in America had the T-shape one side to take either plug.

I just thought maybe they had a different 20A outlet in Canada, though I can't see any in my big Graybar catalog.

Frank:
Was the guy right about the Canadian code requiring 20A recepts. on a 20A branch?

The only variation for Canadian recepts. I can see in the catalog is that some have slotted & Robertson screws instead of slotted/Phillips.

I'm not sure what "Robertson" screws are, but I'm guessing they're your name for what we call "Pozi-Driv" (sic) - Similar to Phillips but with a small star-like arrangement in the center.

>I'm not sure what "Robertson" screws

I thought the guy was Roberson. Anyway, That's what I call the square holes.

>what we call "Pozi-Driv"
That might be what we call Torx.
But there are some other star-like designs and I don't know all the names.

The hexagonal holes are named for Allen.

The square ones are called Robertsons, named after the Canadian(!) inventor. Our devices use them. Irritatingly, a device and the box use two different sizes: #6 and #8 (or #2 & #3)
They're great, otherwise. No stripping, and the driver will actually hold the screw in place on it's own.

Definitely "Robertson" in the Graybar catalog.

We have Torx heads here as well but Pozi-Driv is something different. From the markings on tools etc., it appears that "Pozi-Driv" is only a trademark in Britain/Europe, hence my suggestion that they might go under a different trade name elsewhere.

Ah... Sounds as though they're not the same thing then.

A Pozi-Driv screwdriver of the correct size will fit a Phillips head well, but not vice versa.

Paul,

I've heard the name pozi-drive (don't know spelling) in reference to a type of screwdriver tip on Auto mechanics' Snap-On brand tools. That was about 25 yrs ago.

Here's a picture I found:

[img]http://us.st7.yimg.com/store4.yimg.com/I/toolsplus_1649_33971656[/img]

Bill

[This message has been edited by Bill Addiss (edited 09-05-2001).]

That looks like the Pozi-Driv tip. If you look closely between the main cross blades, you can see the smaller flutes that fit the star shaped middle of the head.

These heads have become very popular here for general building screws etc. over the last 30 years or so.

Pozi-Driv is the official trademark, but you'll also see lots of other corruptions: Pozidrive, Posi-drive, Posidrive, etc.

The CEC does not permit 15 amp receptacles on a circuit with a 20 amp circuit breaker.

There are two styles of 120V, 20 amp receptacle approved for Canada. The first is the normal 5-20R, which has one vertical slot and one horizontal slot. The second is the U.L. style T-slot receptacle with a dual 15/20 amp rating. This has one vertical slot, and a second slot which looks like the letter T on its side. It requires a 20 amp breaker, but you can insert a 15 amp cord cap into it.

Regards,
Brian

Hello Brian, and welcome.

Many thanks for your information. Like all the guys south of the 49th here, I'd only ever seen the normal U.S. 20A receptacle which accepts 15 or 20A plugs.
If you have another type in Canada which doesn't have the T on the neutral, then I can see how the reply on the DIY site makes sense.

I would've thought the regular NEMA 5-20 recepts. would be more convenient. Are the Canadian 20A-only types widely used in place of the U.S. style?

Rule 14-600 - Protection of Receptacles
Receptacles shall not be connected to a branch circuit having overcurrent protection rated or set at more than the ampere rating of the receptacle except as permitted by other Sections of this Code.

Rationale for Rule 14-600.
Receptacle configurations are standardized according to voltage and ampere ratings as shown in Diagrams 1 and 2 of the CE Code, Part I. The configurations for either locking or non-locking types are arranged to prevent connection of a load greater than the rating of the receptacle.

Intent for Rule 14-600.
We intend that branch circuit overcurrent protective devices supplying receptacles be rated not larger than the rating of the receptacles, except in specific circumstances as allowed in other Sections (eg, Rule 42-004).

Rule 42-004 Receptacles and Attachment Plugs

Where a welder is cord connected, the rating of the receptacle and attachment plug shall be permitted to be less than the rating of the overcurrent devices protecting them, but not less than the ampacity of the supply conductors required for the welder.

Rationale for Rule 42-004.
To allow for portability, certain welders need to be connected by a receptacle and attachment plug cap. This Rule provides an exception to the normal requirement of receptacle sizing, as specified in Rule 14-600, because of the nature of the connected load.

Intent for Rule 42-004.
We have determined that the ampacity of the branch circuit conductors of the welder should be the determining factor in selecting the current-carrying capacity of the receptacle. Ampacity of the branch circuit conductors has been chosen rather than the rating of the overcurrent device, because the latter is sized to accommodate short-duration inrush currents, which occur during start-up, as well as the continuous current of the welding operation.

Tony Moscioni
Electrical Inspector
© Electrical Safety Authority – 2001

>I would've thought the regular NEMA 5-20 recepts. would be more convenient. Are the Canadian 20A-only types widely used in place of the U.S. style?

They are more convenient, but until recently weren't widely used because they require a 20 amp breaker and #12 wire, which makes them more expensive to install than a 15 amp receptacle. The Canadian-style 20 amp only receptacle has always been available, but is a low volume item because 120V 20A devices aren't too common.

Where we use the U.L. style 20A T-slot receptacle is in residential kitchen counter circuits as an alternative to 15A split 3-wire circuits. A 20A single pole breaker is quite a bit cheaper than a 15A two pole, and 2/12 loomex is a somewhat cheaper than 3/14.

So does the NEC allows you to wire a 15/20A T-slot receptacle with #14 wire and a 15A breaker, or is it just that you can use a 15A receptacle on a 20A breaker with #12 wire?

Regards,
Brian

[This message has been edited by granam (edited 11-30-2001).]

Brian,

I've spent a fair bit of time in the States, but I'm actually in England, so by no means am I fully acquainted with all the intricacies of the NEC, although I've studied a certain amount (and also learned a lot more from the people on here - Thanks guys!).

So far as I interpet it, I don't think the NEC allows a 20A recept. to be wired on a 15A branch. I do know that the U.S. regularly uses 20A branches which can feed a mixture of 15 and 20A recepts. I had this where I stayed, with 20A recepts. in the kitchen and 15A elsewhere.

I'm sure one of our American friends will put me straight if I've got any of that wrong.


*
Tony,

Thanks for the official wording. I think the max. overcurrent device rating and the recept. rating is something which has many different approaches. For example, over here our "code" allows the old-style 5A recepts. on a branch circuit of up to 15A.

>For example, over here our "code" allows the old-style 5A recepts. on a branch circuit of up to 15A.

I was under the impression that British receptacles use internal fuse links sized to the rating of the receptacle.

Is that correct?

Regards,
Brian

You're almost correct. The fuse link is actually fitted into the plug, not the receptacle, and is selected to match the appliance This is the current style plug which is standard for new work, but there are also older style plugs rated 2, 5 and 15A which don't have fuses.

Go to "Non U.S. Electrical Systems" and look at the threads "Hello from U.K." and "Rings circuits U.K. style" for more info on the fused plug.

When I get a chance I'll post some notes there on the older type arrangements.

[This message has been edited by pauluk (edited 12-01-2001).]