Barrier and slot within reduced area on a PCB

Imagine this situation in a little area of your PCB:

According to the worst case and used material, I need a creepage distance = 30mm. According some tables, clearance must be 30mm. First Red banana and black connector will have the same voltage: HV. They will be connected by wire. But the next red banana could be at different voltage from black connector, being LV. Difference between black connector and the right red banana could arrive to 6 KV.

As the available PCB space is little I saw 2 solutions:

1. The cheapest and easiest way is to the make a slot on the green area. I will obtain desired creepage distance making the slot larger. But the problem is that clearance will surelly have a shorter distance than 3cm. Making the slot larger doesn't have any effect on clearence.

2. to put a barrier on the green area in order to increase creepage and clearance and achieve 3cm for both distances. But this kind of solution is expensive, especially if there are more than one barrier to fit.

My questions:

• So, despite creepage has the priority I guess I will ensure the clearance will be achieved too, does it? So slot could not work here. Would you put a barrier or a slot?

• If slot, any especial way to follow for drawing the slot shape?

• What is the slot width? is it any way for calculating the hole width? I have read that 1mm could be de minimal slot width. But is ever a width = 1mm for enought?

• Strange. I can’t think of any situation where creepage have priority over clearance. Lack of clearance will have drastic and immediate effect (flashover) whereas lack of creepage will take in most cases take months or years of continuous high voltage before you have breakthrough. I have seen 2 mm minimum for slot width, but it depends on your requirements and pollution degree and type. Commented Jul 15, 2019 at 11:21
• Also related: electronics.stackexchange.com/questions/448002/… Commented Jul 15, 2019 at 11:21
• ”but creepage will normally need to be bigger or equal distance than creepage” Please take a look at this sentence too. Commented Jul 16, 2019 at 9:39
• @winny, maybe I'm not explaining so well, sorry about confusion. I mean "Another item to note is that creepage requirements are always greater than or equal to the associ­ated clearance requirement.". Creepage and clearence have a minimal requirements, but creepage will normally need to be bigger or equal distance than clearance. Thanks for your answer -I have just fixed the sentence-. Commented Jul 16, 2019 at 9:47