ECN Forum Forums General Topics of the Trade General Discussion Area using stinger to nuetral from 3ph delta

I've got a 208v 2wire kiln to hookup, can I use the stinger to neutral from a 240v delta 3ph? for a 59amp 2wire plus ground hookup. I read 208v to ground from the stinger. si there a code issue? and for ocpd can I use 1 leg of a 2pole breakr or should I find a 1pole 70 amp? thanks again chris

I've always been told not to do it, but I can't see a theoretical reason.

There IS a code reason ... namely, that the single pole breaker is almost certainly not listed for more than 150 v. line to neutral. Indeed, even the two pole breakers in that panel ought to be specifically listed for the use .... though I admit that they usually are not! Most two pole breakers are not listed for use with a 'stinger' either.

Another code reason is found on the panel itself. Reading the fine print on the label, again, the panel is listed only for two pole or three pole circuits with a delta service. What you're supposed to do is use this panel to feed a separate single phase panel.

The hardware question would be, is this real 3 transformer delta? If it is Delta Vee with 2 transformers you will drag one side down (BC vs BA) and the other one up.

it must be a delta vee, there are two transformers on the pole one large and one small, pge hooked them up when we put the service in, I was only a apprentice at the time, and havent looked at the hookup to the four sets of parallel 250s we pulled in. I'll have to look up delta vee set ups, but will just tell the client to get new elements. chris

You also have to be careful with 240 single phase loads on that setup. Be sure it is using the 120/240 transformer not the stinger leg ... for the same reason. We used to run into that problem in computer rooms that were on delta services. If you can keep your single phase loads balanced around the phases you can get away with it but if they are lopsided AB/BC it can screw up the balance. (assuming orange is B)

Any load connected to the stinger to neutral reduces the ability of the transformer to handle other "normal" line to neutral loads.

Theoretically it is possible, practically it is not advised.

the kiln says its 59 amps at 208, I called the mfg. tech, he said it would increase the amps on the circuit if run at 240v, but I think he was wrong wouldnt it lower them at 240v, this is SKUTT kilns and they build for both 208 and 240 and have electronic time/temp controllers, are there different electronics for 208 and 240? or wouldnt it be just rated for 250v, and its a resistive load so wouldnt it just get up to temperature faster? Sorry if this might seem basic, but my daddy brain isnt what it once was and its not always possible to get a quiet space. thanks again, chris

When you change the voltage, a heating element is affected by the square of the change. That is, double the volts, get four times the heat.

The kiln maker ought to have replacement parts that are rated for 240 volts. This is the best solution; I've had to make such changes on commercial water heaters.