cat 941 tripping breaker while heating glow plugs

Usually or at least preferred is to have the glow plugs wired through the ammeter so you can see what is going on. Yes you probably have a short, either in the glow plugs or in the harness and wiring, also check the solenoid. Glow plugs should draw about 5-7 amps each.

yes the meter goes to around -30 when i turn the glow plugs on, ill give it a look and see if i can find anything

yes the meter goes to around -30 when i turn the glow plugs on, ill give it a look and see if i can find anything

30 amps may be normal--mine goes to around that when I turn mine on

30 is normal for all 4 to be working

The heater plugs on a 941 (4 cylinder) should draw 5 amps per plug = 20 amps, if your fuse trips look at the heater rail wire for the fault.
tctractors

ok i will check the wires when i get time but it has always read 30 when all 4 was working, but have ever used it in winter months and had to heat that long

Unless you have a 6 cylinder engine in your 941??? that will draw 30 amps, lets stick to the standard spec of a 4 cylinder 330C or 3304 as in the 941B you will only draw 20 amps, it could be dirt or crud stacked up around the plugs that is causing you pain, but the usual issue is a faulty wire leading onto the plug, the heater wire rail is a low cost item to replace Non OE or Classic Part (CAT), if you wanted to test your heater plugs, they are best removed and tested with a Battery Charger 12 or 24 volt set on low output, it is safer to use 12 volt as it will work and you will have less chance of harming yourself, you don't need to see them glow red just get warm enough to smoke, if it's -20 deg outside it will still only draw 20 amps on good plugs as the plugs don't know it's really cold.
best of luck tctractors

visually i didnt see nothing wrong with none of the wires that i could see. the amp gauge is going to just shy of 30, its a 60 amp gauge so kinda harder to read than stock 30 amp one the manual shows. with just one plug hooked up it is between 0and10 like it should be but with all 4 it goes to 30 so maybe the gauge isnt reading just right. anyway do yall think the problem could be in the actual breaker? i cranked it yesterday, didnt time how long i had the plugs on but it didnt throw the breaker and the dozer cranked though it could have used the plugs a few more seconds because it didnt crank smooth.