Double Pole Circuit Breaker - the Sequel

British Standard 7671 still prohibits switching the neutral.

British Standard doesn't really apply here - I am using these in the USA - NEC trumps all here.

Apparently your friends across the Channel have no problem opening a neutral.

PWS. BS 7671 does not preclude DP switching.

It does stipulate where it shoud be used though.

Does it depend on its location,in final circuit or main incomer in a consumer unit?.

be sure and wrap the fuses with aluminum foil to avoid nuisance fuse blowing

Don't need to wrap in foil when it is from Europe - the dummy fuse is solid brass and is quite common in their applications.

Major fuse manufacturers have a part number for these beasties in their European listings.

Quote Phys "Invariably the 120VAC circuitry comes in with a double pole circuit breaker, or a double pole fuse block with a brass dummy in the neutral bay. Overloads can't trip out the neutral without the 120V side on the breaker and the solid brass dummy is never opening. Therefore no violation of the NEC concerning the opening of the neutral (grounded conductor) without the power opening."

The breaker must be feeeding 2 120 volt ckts. The neutrals do not have overload protection and are not switched. Why would you want to do that?

No - the standard European (continental - don't know about the Brits) wiring methods always puts a double pole circuit breaker or the double pole fuse block with dummy in their 230V single phase (230V to neutral - not 230 across two phases) in all their single phase circuits. They assume we do the same here for our 120V, and wire appropriately. The double pole devices are feeding but one circuit. I can definitely verify this as I must redraw the schematics and remove all the non-English wording and change some definitely European symbols to more accepted ones for this side of the pond before selling the end product.

I didn't mention it, but I also get the opportunity to build these from scratch from their drawings on occasion - at that point all the double pole devices they have in their drawings disappear - but that is not a problem as no money was spent on double pole devices. I was just wondering if changing already built ones was a waste of time and money.

Let's put it this way - if you received a panel for use in the USA with double pole devices in 120V circuits, would you want it rebuilt, or would you just go with it as it?

What we have here is a....

This is not switching - it is over current protection. Per NEC 240.22 you cannot have an over current device in series with any conductor that is ungrounded, UNLESS

1. The overcurrent device opens all conductors of the circuit and is designed so that no pole operates independently.

2. This one does not apply.

Conditions met by the circuitry described - so it is NEC legal. (once I correct the other mentioned violations)

As I said in another reply, the big question, and the one I should have asked, is would you accept this panel at your facility if it had double pole overcurrent devices in a 120VAC circuit? If not then I am not wasting money and time. If most would accept it, then I am.

Have you ever received a jolt from a neutral carrying load from a second phase?

Thank you - that is precisely what I was thinking when I modified my first panel. I figured the electricians on this side of the big pond would be confused by a double pole protective device on a 120VAC circuit.

If you think that is a problem, there is also another common wiring problem I don't have to ask about. We also get 240VAC single phase panels with the same arrangement because the builders in Europe are used to that being the voltage to neutral. Obviously one never wants a dummy fuse on either side of a 240V circuit in the USA. Actually, we never want a dummy fuse - ever.

You mention it, but have you ever seen an OSHA inspector actually look at an electrical installation? The ones we get here look for guarding issues on machinery, measure clear space in front of panels, and look for over use of extension cords, but have never even opened the cover on a panel box. The panel wiring we are discussing would be a very tough one to get by them if they ever did see it.

I don't see any mention of UL listing on any of your devices.

How do you get by that?

Never said they didn't have them either. The individual components are Allen Bradley, Mersen, Schneider, and so on and besides the CE mark, have UL listing on them. (I have the Ul file numbers on record to prove it)(yeah - the dummy fuse obviously has no UL listing, but it is CE marked) Actually saw one of these panels sent to Canada without replacing the fuse blocks and dummies and CSA said okay. They have no problem with the dummy fuses, but they aren't UL either. I never checked into it, but doubt we could approve a panel with a dummy fuse in a true UL 508A inspection, which we can do when required.

Most customers don't require a 508A inspection on process equipment control panels, which I never understood. they are happy with the UL mark on everything except the overall assembly. The question is not how do we get by with that, it is how does the end customer get by without the panel being inspected? As I said, we are approved to do a 508A inspection, but rarely get to charge for it. There is no question that when I must have a 508A inspection sticker on a panel, we are going to be re-design it to USA standards and codes and build it here - not over there.

The original question concerned those panels we don't have to have a UL sticker on.

All righty...good enough for me

I would hope that the customer, or end user, would have the final inspection in mind before ordering equipment...but then again...

Yeah - of course they always do that - RIGHT - have had to have local UL in the customer's region inspect our panel because the UL 508A inspection was never ordered. The other conflict is when shipping to the Golden State. They always have to have the weirdest laws. They require a full product UL approval on all items - not just electrical devices. Aren't many local UL inspectors who are going to look at tanks, and valves, and piping... Those end up being done at the customer's site - but at least that is known from the start.

It is worthwhile to mention here the practices in every country(UK,USA,south america,europe,russia,japan,china,australia etc etc) regarding neutral breaking in single phase final circuit(lighting/sockets),incomer(dp,tp.4p) and so on for CR4 members to know them.Otherwise it creates confusion in readers from different parts of the world.

Very good - noted.

However this concerned over current protection, not switching the neutral wire in a final circuit as one thinks of that. This is the overcurrent device, not a switch in the neutral line, as one might put improperly in a wall for control of lights. Yes one could switch off the instrument or single phase motor or whatever the load is with the circuit breaker in a typical industrial control panel, but that is not the intent of the circuit breaker, nor even an easy task to do. In normal operation the panel door remains shut and one must kill the incoming power to enter it to access the double pole circuit breakers in this discussion. This is also a fairly common requirement in North America, Europe and Asia. At that point, we are not talking normal operation, but some sort of maintenance or repair, hopefully with trained electricians.

I really doubt any country would allow the neutral to be switched in a common public useable final circuit such as lighting and receptacles. If so, would you tell me where and I will be sure to avoid that place.

Actually, a switch in a neutral was acceptable in the "knob and tube" wiring days in the USA. Got removed from a ladder once cleaning a light fixture in a house wired in the 1920's that was "turned off". Yeah - the neutral was off, but not the AC voltage.