ECN Forum Forums General Topics of the Trade General Discussion Area Blowing fuses. - Help

I need some help.

A customer with a rental property that has fuses that blow costantly on a dryer.

I tested and found no problem. Dryer pulling 25-28 amps while I was there. I figured the old dryer was overheating and blowing over time, so I told them to buy a new dryer.

Customer buys a new dryer and fuses blow more than before. I test and find 30 amps on 1 leg and 24 on the other. At this visit the voltage was 250v, 130 on 1 leg, 120 on the other. I called the POCO and they sent a crew out. The crew replaced the line from the transformer to the house because of bad insulation damage. Figured that would be the end of it.

Today they call back and say it's still blowing fuses. I'm stumped. The tenant thinks the problem is the fuse panel and while I'd love to sell a new service that won't solve the problem. There is no load on this circuit other than the dryer. What else should we look at? Thanks

[This message has been edited by Electric Eagle (edited 02-10-2005).]

Eagle:
Do the fuses blow right away, as a 'short' or are they blowing after the unit is operating for a while?

You may have a heating situation within the fuseholder (screwshell) or the clips may be damaged by heat and lost the "spring tension" to maintain a low reststance connection.

Are they time delay fuses??

EE sell them a new service anyway.... They have fuses.... Let them recover from thier other problems first.

Wow! This one sounds wacky, are you getting over voltage everywhere, or just this circuit? If so its time for a new tranny from the POCO. Otherwise, high resitance, lost neutral and/or ground is my guess.

Amperage seems too high for this as well. While the dryer circuit is rated for 30A, it should not be pulling 30A!

I replaced the fuses with Time Delay. The voltage problem was on the entire service, notjust the dryer. I haven't been back since the POCO was there, so I don't konw is they fixed the voltage. I thought if they evened out hte voltage, the amperage would also even out to maybe 26/26 instead of 30/24, that still is a little high.

The motor is only 120 volts so the amp reading will always be higher on one leg. You should see this difference on the neutral conductor.

The old and new dryers are drawing too much current, but it is because of the higher than normal voltage. This happens when utilities over the years replace older smaller high voltage cables with bigger ones to reduce line loss from much heavier loads. The transformers therfore put out higher voltage on the secondary side. The POCO will usually change out the transformer if you call them.